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Musculoskeletal Injury in Professional Dancers: Prevalence and Associated Factors. An International Cross-sectional Study
by
Craig Loren Jacobs
A thesis submitted in conformity with the requirements for the degree of Master of Science
Graduate Department of Institute of Medical Science University of Toronto
© Copyright by Craig Loren Jacobs 2010
Musculoskeletal Injury in Professional Dancers:
Prevalence and Associated Factors.
An International Cross-sectional Study
Craig Loren Jacobs
Master of Science
Institute of Medical Science University of Toronto
2010
Abstract
Purpose: To determine the prevalence and factors associated with injury in professional ballet
and modern dancers, to explore dancers’ attitudes and perceptions of injury, and to assess if
dancers are reporting their injuries and reasons for not reporting injuries.
Methods: A cross-sectional survey was undertaken in professional ballet and modern dance
companies in Canada, Denmark, Israel, and Sweden.
Results: The point prevalence of injury in dancers is high (55% ballet; 46% modern) and most
have chronic pain. Years dancing professionally and rank were associated with injury in ballet
dancers. Attitudes towards injury vary and some dancers are continuing to dance when injured.
Greater than 15% of all injured dancers have not reported their injury.
Conclusions: Injury is common in dancers and there is an urgent need to investigate
interventions to help control injury and understand the long-term implications of these conditions
in this population.
ii
Acknowledgments and Contributions I wish to express my sincere gratitude to my supervisor Dr. J. David Cassidy for his guidance,
supervision, and scientific integrity and for providing me with such an important and exciting
research opportunity. I am truly grateful to my cosupervisor, Dr. Pierre Côté, for his belief in the
importance of my research. His excitement for research and science is truly infectious and
inspiring. I would like to thank Dr. Eleanor Boyle for her collaboration, contributions and
guidance with the statistical analysis. I am so grateful for her time, patience, and expertise. I
thank Dr. Carlo Ammendolia for his invaluable insights, input, and suggestions for my work. I
am so appreciative of my entire program advisory committee, each of whom has provided me
with guidance and inspiration.
This was a truly collaborative international effort that would not have been possible without the
contributions of Dr. Eva Ramel, Dr. Jan Hartvigsen, and Dr. Isabella Schwartz. They were
instrumental in applying for the ethics board applications in Sweden, Denmark and Israel
respectively. Dr. Ramel helped to develop relationships and communication with both the Royal
Swedish and Royal Danish Ballets. Additionally, Dr. Ramel’s previous scholarly work regarding
professional dancers has been an invaluable source of knowledge, and her willingness and
excitement to discuss dance health issues with me was extremely helpful. All three collaborators
reviewed the study questionnaire and made site specific recommendations. They provided me
with support during the survey completion in each country. They provided supplies, helped with
logistics and communication and gave me a greater understanding of social support and work
conditions in each country. I am so thankful for the amount of time and energy they have
contributed to this project.
Dr. Cesar Hincapié published the first systematic review of injury and pain in dancers which
served as a springboard and inspiration for my study. He guided me through the best evidence
synthesis systematic review update process and served as the second reviewer for all the
literature. I wish to thank him for that guidance and for his contribution to my research. I would
also like to thank Dr. Paula Stern for her encouragement over all these years, her role in the pilot
of the questionnaire, and for starting me off on this path. My deepest gratitude also goes to Dr.
Heather Shearer who has always been ready with advice and support whenever I needed it,
without question. I commend and thank Monica Alder for her wonderful design of the
iii
questionnaire which played an integral role in its success and appeal. The staff, scientists, and
students at CREIDO were so helpful over the years in so many ways, and I thank them all for
their input, suggestions, and incredible help.
Of course, this work would not have been possible without the participation of the dance
companies involved. I thank all the dancers, artistic staff, and administrative staff of the National
Ballet of Canada, Toronto Dance Theatre, Royal Swedish Ballet, Cullberg Ballet, Royal Danish
Ballet, Batsheva Dance Company and Ensemble, and the Kibbutz Contemporary Dance
Company and its junior company. I would like to especially thank those individuals from these
companies who facilitated the implementation and logistics of the study including Joanna Ivey,
Bridget Cawthery, Lars Anderstam, Jane Salier-Eriksson, Karen Bonnesen, Yaniv Nagar, Claire
Bayliss-Nagar, and Rachel Ariel.
I wish to thank all of the organizations who provided financial support for my research and
graduate studies: the Canadian Institutes of Health Research, the Artists Health Centre
Foundation, the University of Toronto, and the Canadian Memorial Chiropractic College. This
project was also partially funded by the Centre for Research Expertise in Improved Disability
Outcomes (CREIDO) which received substantial funding through a grant provided by the
Workers’ Safety and Insurance Board (WSIB).
I thank my parents, Michael and Shelley, for their never ending support and love. I am so
grateful to my partner Atsmon who has constantly reminded me of the importance of my work at
every stage and has been an incredible source of strength, encouragement, and love.
iv
Table of Contents
ABSTRACT.................................................................................................................................. II
ACKNOWLEDGMENTS AND CONTRIBUTIONS .............................................................III
TABLE OF CONTENTS .............................................................................................................V
LIST OF TABLES ..................................................................................................................... IX
LIST OF APPENDICES .......................................................................................................XI
LIST OF ABBREVIATIONS .................................................................................................. XII
CHAPTER 1: INTRODUCTION................................................................................................ 1
1.1 Statement of Problem ............................................................................................................. 1
1.2 Literature Review ................................................................................................................... 2
1.2.1 Screening for relevance...................................................................................................... 2
1.2.2 Critical review of the literature .......................................................................................... 3
1.2.3 Characteristics of musculoskeletal injury in dancers......................................................... 3
1.2.4 Prevalence and associated factors of musculoskeletal injury and pain in dancers. ........... 4
1.2.5 Incidence of and risk factors for musculoskeletal injury and pain in dancers ................... 8
1.2.6 Definition of Injury ............................................................................................................ 8
1.2.7 Injury Reporting............................................................................................................... 10
1.2.8 Assessment Tools for Musculoskeletal Injury and Pain in Dancers................................ 10
1.3 Environmental Scan of Healthcare and Social Programs................................................. 11
1.4 Summary and Rationale....................................................................................................... 13
1.5 Primary Objectives and Research Questions ..................................................................... 13
CHAPTER 2: METHODS AND MATERIALS ...................................................................... 15
v
2.1 Study design........................................................................................................................... 15
2.2 Source population/Setting ................................................................................................... 15
2.3 Inclusion/Exclusion Criteria ................................................................................................ 17
2.4 Recruitment/Survey Methodology ...................................................................................... 17
2.5 Description and Pilot-Testing of the Questionnaire .......................................................... 18
2.5.1 Description of the study questionnaire ............................................................................ 18
2.5.2 Pilot-testing of the study questionnaire............................................................................ 18
2.6 Measurement and Definition of Variables.......................................................................... 19
2.6.1 Sociodemographic variables ............................................................................................ 19
2.6.2 The Self-Estimated Functional Inability because of Pain (SEFIP) Questionnaire ......... 20
2.6.3 Eleven-point Numerical Rating Scale (NRS-11)............................................................. 21
2.6.4 Current Treatment and Pain Medication Use................................................................... 21
2.6.5 Injury Status/ Self Reported Injury .................................................................................. 21
2.6.6 Injury Characteristics ....................................................................................................... 21
2.6.7 Injury Reporting............................................................................................................... 22
2.6.8 Dancers’ Attitudes and Perception of Injury ................................................................... 22
2.6.9 Contextual Company Information ................................................................................... 22
2.7 Ethics...................................................................................................................................... 22
2.8 Statistical Analysis ................................................................................................................ 23
2.8.1 Data entry, double data entry, and data cleaning ............................................................. 23
2.8.2 Descriptive Statistics........................................................................................................ 23
2.8.3 Prevalence of Dance-related MSK Injury........................................................................ 23
2.8.4 Factors associated with MSK-injury in professional dancers.......................................... 24
CHAPTER 3: RESULTS ........................................................................................................... 25
3.1 Response rate......................................................................................................................... 25
3.2 Data entry error rate ............................................................................................................ 26
vi
3.3 Sociodemographic characteristics of the study population............................................... 26
3.4 Self Estimated Functional Inability because of Pain (SEFIP) scores............................... 30
3.5 Numeric Rating Scale Scores: Dance related pain over the last week. ............................ 34
3.6 Current treatment................................................................................................................. 37
3.7 Pain Medication Use ............................................................................................................. 42
3.8 Injury Prevalence.................................................................................................................. 43
3.9 Factors associated with self-reported dance-related musculoskeletal injuries (SRI) in
dancers. ........................................................................................................................................ 46
3.9.1 Univariate analysis (crude analysis) ................................................................................ 46
3.9.2 Multivariable analysis (logistic regression) ..................................................................... 50
3.10 Factors associated with SEFIP score of ≥3. ..................................................................... 51
3.10.1 Univariate analysis (crude analysis) .............................................................................. 51
3.10.2 Multivariable analysis (logistic regression) ................................................................... 56
3.12 Characteristics of Prevalent Injuries ................................................................................ 57
3.12.1 Body region injured ....................................................................................................... 57
3.12.2 Injury Duration............................................................................................................... 60
3.12.3 Injury Severity ............................................................................................................... 62
3.12.4 Time Off Work in Past Year.......................................................................................... 62
3.12.5 Recurrent Injuries........................................................................................................... 66
3.13 Relationship between SEFIP scores and SRI ................................................................... 68
3.14 Reporting of Dance-related Injuries ................................................................................. 68
3.15 Dancers’ Attitudes and Perceptions of Injury.................................................................. 73
3.16 Company Contextual Information .................................................................................... 80
CHAPTER 4: DISCUSSION ..................................................................................................... 82
4.1 Principal Findings................................................................................................................. 82
vii
4.2 Implications of Principal Findings ...................................................................................... 88
4.3 Strengths and Limitations.................................................................................................... 91
4.4 Future Directions .................................................................................................................. 94
CHAPTER 5: CONCLUSIONS ................................................................................................ 95
REFERENCES............................................................................................................................ 96
APPENDICES …………………………………………………………………..…………….100
viii
List of Tables Page
Table 1.1 Cross-sectional studies of prevalence and associated factors of
musculoskeletal injury and pain in dancers 6
Table 2.1 Number of eligible dancers in each dance company 16
Table 3.1 Response rates 25
Table 3.2 Sociodemographic characteristics of participating dancers:
age, sex, marital status, and low-income cut-offs. 28
Table 3.3 Characteristics of participating dancers: Body Mass Index,
low body weight, and years dancing. 29
Table 3.4 Country of Origin 30
Table 3.5 Frequency of SEFIP scores ≥ 3 (by company) 32
Table 3.6 Frequency of SEFIP scores ≥ 3 (by style, sex) 33
Table 3.7 Average dance-related pain over last week,
Numeric Rating Scale-11 scores 35
Table 3.8 Pain severity using Numeric Rating Scale-11 cut-points.
Average dance-related pain over last week 36
Table 3.9 Dancers currently receiving treatment for dance-related pain 38
Table 3.10 Treatment from Healthcare Practitioners (only dancers
currently receiving treatment) 39
Table 3.11 Frequency of Treatment from Healthcare Practitioners
(only dancers currently receiving treatment) 40
Table 3.12 Site of Current Treatment (only dancers currently receiving
treatment) 41
Table 3.13 Pain medication use in last week (all dancers) 42
Table 3.14 Current Injury Status 44
Table 3.15 Point prevalence of Self Reported Injury 45
Table 3.16 Point prevalence of SEFIP ≥3 Injury 45
Table 3.17 Univariate Analysis (ballet dancers only) – Self Reported Injury 47
Table 3.18 Univariate Analysis (modern dancers only) – Self Reported Injury 49
Table 3.19 Final Model for Logistic Regression Analysis. Factors Associated with Self Reported Injury (ballet dancers) 51
ix
Table 3.20 Univariate Analysis (ballet dancers only) – SEFIP score of ≥3 53
Table 3.21 Univariate Analysis (modern dancers only) – SEFIP score of ≥3 55
Table 3.22 Final Model for Logistic Regression Analysis. Factors Associated SEFIP score of ≥3 (ballet dancers) 56
Table 3.23 Body Region Injured (current most problematic injury of
injured dancers) by style and sex. 58
Table 3.24 Body Region Injured (current most problematic injury of
injured dancers) by company 59
Table 3.25 Duration of Injury (by style and sex) 61
Table 3.26 Duration of Injury (by company) 61
Table 3.27 Injury Severity (by style and sex) 64
Table 3.28 Injury Severity (by company) 64
Table 3.29 Time off work due to current injury in past year (by style and sex) 65
Table 3.30 Time off work due to current injury in past year (by company) 65
Table 3.31 Recurrent Injury (by style and sex) 69
Table 3.32 Recurrent Injury (by company) 67
Table 3.33 Highest Reported SEFIP Score for Injured and Non-injured
Dancers 68
Table 3.34 Frequency of non-reported injuries 69
Table 3.35 Reasons for not reporting an injury 70
Table 3.36 To whom are dancers reporting their injuries? 71
Table 3.37 Injuries Reported as Work Injuries 72
Table 3.38 Responses to Attitudinal Questions 75
Table 3.39 Company Contextual Data for the 2007-08 Season 81
x
List of Appendices Page
Appendix 1 Electronic Database Search Strategies 100
Medline 101
Cinahl 102
Appendix 2 Study Questionnaire 103
Appendix 3 Research Ethics Board Approvals 119
University of Toronto 120
University Health Network 121
Hadassah Hospital (Israel) 122
Datatilsynet (Denmark) 123
Regional Ethics Committee, Lund (Sweden) 128
Appendix 4 Copyright Acknowledgement 130
xi
List of Abbreviations
B: Ballet
BAT: Batsheva Dance Company
BJHS: Benign joint hypermobility syndrome
BMI: Body mass index
CAD: Canadian dollar
CI: Confidence interval
CUL: Cullberg Ballet
ENS: Ensemble Batsheva
KDC: Kibbutz Contemporary Dance Company
KDC2: Kibbutz Contemporary Dance Company 2
M: Modern
MD: Medical doctor
Med: Median
MSK: Musculoskeletal
NA: Not available
NBC: National Ballet of Canada
ND: No data
NRS: Numeric rating scale
NSAIDs: Non-steroidal anti-inflammatory drugs
OR: Odds ratio
P: Professional
PP: Pre-professional
RDB: Royal Danish Ballet
RSB: Royal Swedish Ballet
SD: Standard deviation
SEFIP: Self Estimated Functional Inability because of Pain Questionnaire
SRI: Self-reported injury
TDT: Toronto Dance Theatre
U: University
xii
xiii
WSIB: Workers’ Safety and Insurance Board
YS: Young student
β: Beta
ρ: Rho (Spearman’s rank correlation coefficient)
Chapter 1: Introduction
1.1 Statement of Problem
Dancers are both artists and athletes. Professional dancers train many years, often from a
young age, to attain one of the few positions available in professional dance companies.
They are subjected to fierce competition from other talented dancers, as well as intense
scrutiny from teachers, choreographers, and artistic directors. They must possess innate
talent, yet obtain a high level of skill and physical ability. In one study comparing ballet
to 61 other sports, it was deemed the second most demanding physical activity on par
with bullfighting and second only to football.1
The number of professional modern and ballet dance companies in any one country is
small. Therefore, dancers from around the world compete for the few positions available
in these companies. This often results in a very internationally diverse work population.
Competition does not end once the dancer achieves a professional dance position.
Professional ballet dance companies have a ranking system. Most dancers start in the
corps de ballet and try to work their way up to soloist and then principal dancer positions.
Although modern dance companies may not employ a ranking system, dancers still
compete for roles. Injury or pain may impede a dancer’s ability to attain or maintain their
position or roles in a company and, at worst, drastically shorten a dancer’s career. The
professional dancer’s career is extremely short with most dancers retiring from
performance in their mid to late 30s in the United States of America and between the ages
of 41-44 in Sweden. 2, 3
A recent systematic review has found the dance medicine literature regarding
musculoskeletal injury and pain to be “young and heterogeneous” identifying only 32
published articles as scientifically acceptable. 4 The prevalence of musculoskeletal
(MSK) injury in professional dancers ranges from 20-84% while the prevalence of MSK
pain is as high as 95%.4 This broad range of prevalence estimates is likely due to
different definitions of injury and study methodology. The paucity of high quality studies
1
2
for an occupational group which is at high risk for MSK injury and pain points to the
importance of further research in this area. The objective of my thesis is to add to the
existing literature on the burden and associated factors of MSK injury and pain in
professional ballet and modern dancers by updating a systematic review of the literature
and by surveying professional dancers from Canada, Sweden, Denmark, and Israel.
1.2 Literature Review
A systematic review of the entire dance medicine literature up to 2004 was performed by
Hincapié et al.4 Two themes were identified: (1) MSK injuries and pain; and (2)
metabolic and nutritional disorders. With the first author of that study, I updated this
review dealing with MSK injuries and pain to 2008 using an identical search strategy
(Appendix 1). The primary sources of literature were the electronic databases MEDLINE
(2004 to March 2008) and CINAHL (2004 to March 2008). Indexed terms and text words
such as dance, dancer, dancing, athletic injuries, occupational injuries, sprains and
strains, musculoskeletal diseases, bone density, menstruation disturbances, eating
disorders, and others were used to search the databases. 4 Additionally, I examined the
reference lists of all relevant studies for additional or unpublished literature.
1.2.1 Screening for relevance
Using a best evidence synthesis approach,5, 6we each independently screened all of the
citations that were identified through the search strategy and using the previous review’s
criteria included: “English language reports; published reports of original research,
systematic reviews, conference proceedings, government reports, guidelines, or
unpublished “grey literature” manuscripts; studies containing original raw data on at least
20 human research participants, including a control group if present; studies examining
the prevalence, incidence, associated factors, risk factors, diagnosis, interventions,
economic costs, prognosis, or other aspects of MSK injury and pain, and metabolic and
nutritional disorders in dancers; and, studies of dancers in any form of artistic dance such
as ballet, modern, tap, theatrical, folk, Flamenco, break-dancing, ballroom dancing, and
ice dancing”.4 Using identical exclusion criteria to the previous review, we excluded:
3
“studies on recreational or exercise forms of dance such as aerobic dancing or social
dancing in clubs, parties or raves; studies on the cognitive, behavioral or learning aspects
of dance; narrative, editorial or clinical reviews, opinion papers, letters to the editor, and
editorials; studies of conditions with questionable clinical relevance or asymptomatic
presentation; studies using cadavers or non-human subjects; and, studies reporting
findings not specific to dancers (e.g., studies where dancers’ information was combined
with other athletes’ information and results could not be evaluated specifically for
dancers)”.4
The first author of the previous review and I independently evaluated each citation’s
relevancy through a two-level screening process. We obtained and reviewed all papers
that were identified as probably relevant, or of unknown relevance in the first level of
screening. In the second-level screening, these were then classified as either relevant or
irrelevant to the systematic review.4
We maintained the 2 themes from the previous systematic review: (1) MSK injuries and
pain; and, (2) metabolic and nutritional disorders. For the purposes of this thesis, I will
extract and include information relevant to the first theme, MSK injuries and pain.
1.2.2 Critical review of the literature
We critically appraised all relevant studies for scientific merit and clinical relevance by
using a priori criteria and computer-based critical review forms.7 Studies were
considered scientifically admissible or scientifically inadmissible on the basis of the
presence of fatal biases and methodological flaws. We undertook a full discussion of each
paper focusing on issues such as design, study population, study conduct, participation
and follow up rates, measurement and analysis.4 I have extracted relevant information
from the accepted papers, and my update of the review for this thesis focuses on studies
relevant to professional ballet and modern dancers.
1.2.3 Characteristics of musculoskeletal injury in dancers
The previous review of MSK injuries in dancers reported that most MSK injuries in
dancers are soft tissue injuries such as sprains, strains, and tendinopathies primarily
4
affecting the lower extremities and back.4 Many studies in my updated review did not
report exact locations of injuries measured; however, of those that did, lower extremity
injuries still predominated followed by hip and low back injury. Three studies accepted in
the review update focused on specific injuries including snapping hip syndrome, ankle
injuries, and acute hamstring strain.8-10
1.2.4 Prevalence and associated factors of musculoskeletal injury and pain in
dancers.
Hincapié’s review identified six studies that focused on professional dancers and three
studies that included both professional, preprofessional, and/or university level dancers.
All of these studies included ballet dancers while only two of the studies included modern
dancers.4 In my review update, I identified one study that focused solely on professional
ballet dancers,11 one study on professional modern dancers,12 and one study that focused
on a mix of professional ballet dancers and elite ballet students.10
Prevalence estimates varied according to time periods and case definitions with estimates
ranging from 20% to 95%. Two of the better quality studies reported the 1-year period
prevalence of MSK pain in professional Swedish ballet dancers to be approximately 95%,
with 90% of those dancers who were followed up 6 years later reporting recurrent pain.13-
15 One study reported the point prevalence of minor recurrent injury in professional
ballet and modern dancers to be 89%.16 Another study reported the point prevalence of
chronic injury in professional ballet and modern dancers at 48% and the six month period
prevalence of injury at 42%.17 The majority of studies reported 12-month or lifetime
prevalence increasing the likelihood of recall bias.
Eight of the eleven identified cross-sectional studies reported on factors associated with
MSK injury or pain in professional dancers. Factors reported to be positively associated
with MSK injury or pain include older age18, female sex 14, male sex 19, years of dance
experience18, 20, “overachiever” personality traits18, dance setting17, performance level14,
20, hours of training per day21, menstrual dysfunction21, muscular tension before
performing14, work dissatisfaction14, joint hypermobility19, and psychological
5
factors(stress, anxiety, depression, anger, fatigue and confusion)11. The majority of these
associations are preliminary in nature. Only one study of professional ballet and modern
dancers made use of multivariable statistical methods in assessing the independence of
these associated factors.14 In Table 1.1, I outline the cross-sectional studies of
professional ballet and modern dancers with reported prevalence estimates and associated
factors.
6
Table 1.1: Cross sectional studies of prevalence and associated factors of musculoskeletal injury and pain in dancers Prevalence Estimates Study;Country Style;Level Study Size
(N); Response Rate
Age (y) Outcome Point 6 month
12 month
Lifetime Associated Factors
Chmelar et al.16; USA
B,M; P,U 39 (18 Professional dancers); 64%
18-37 Injury 74% (minor injury); 89% P only
ND 23% (major injury)
ND NA
Hamilton et al.18; USA
B; P 29; 64% 22-41 Injury ND ND ND 20-79% Age, years of dance, personality traits
Bowling17; UK B,M; P 141; 75% >18 Injury 48% (chronic)
42% ND 84% Dance setting
McNeal et al.20; USA/Canada
B; P,PP,U,YS
350 (99 professional dancers); 80-100%
<13 and ≥13
Injury ND ND ND 20-80% Years of dance, performance level
Kadel et al.21; Sweden
B; P 54; 55% NA Stress fracture
ND ND ND 32% Hours of training per day, menstrual dysfunction
Ramel and Moritz14; Sweden
B; P 64; 84% 17-47 Pain ND ND 69-94%
ND Sex, performance level, muscular tension before performing, work dissatisfaction
Abbreviations: B, ballet; BJHS, benign joint hypermobility syndrome; M, modern; NA, not available; ND, no data; P, professional; PP, preprofessional; U, university; YS, young student.
7
Table 1.1: Cross sectional studies of prevalence and associated factors of musculoskeletal injury and pain in dancers Prevalence Estimates Study;Country Style;Level Study Size
(N); Response Rate
Age (y) Outcome Point 6 month
12 month
Lifetime Associated Factors
Ramel and Moritz13 and Ramel et al.15; Sweden
B; P 128; 87% 51; 60%
17-47 Pain ND ND 61-95%
ND Nonassociated factors: age, sex, workload
McCormack et al.19; England
B; P,PP 287 (71 professional dancers); NA
NA Injury NA (study focused on hypermobility and BJHS)
Sex, joint hypermobility
Adam et al.11; Germany
B; P 54; 78% NA Injury NA ND 87% ND Stress, sleep problems, negative mood states
Scialom et al.12; Brazil
M; P 30; 75% NA Injury ND ND ND 47% NA
Winston et al.10: Canada
B; P,PP 87; 92% >16 Snapping hip syndrome
ND ND ND 91% Movements associated with snap: Grand battement à la seconde (42%), grand plié (25%), développé à la second (22.8%).
Abbreviations: B, ballet; BJHS, benign joint hypermobility syndrome; M, modern; NA, not available; ND, no data; P, professional; PP, preprofessional; U, university; YS, young student.
8
1.2.5 Incidence of and risk factors for musculoskeletal injury and pain in dancers
In the review of Hincapié et al., eight cohort studies of professional dancers were identified.
Only one study focused on professional modern dancers. Five studies focused on professional
ballet dancers and two studies examined both professional ballet dancers as well as university or
high school level ballet students.4 In my review update, I identified an additional five cohort
studies of dancers; however, only one study included professional ballet dancers along with
university and high-school level dancers. The remaining four studies included only university or
preprofessional dancers.
The cumulative incidence of musculoskeletal injury in professional dancers ranged from 40% to
94%; however, the follow-up periods varied between studies.4, 22Four studies reported incidence
densities. One study of professional ballet dancers reported 0.65 injuries per dancer-year.23 A
study of ballet dancers in Sweden reported 0.62 injuries per 1000 dance-hours.24 A study of
modern dancers in the United States evaluating an injury management program reported
incidence per 1000 dance-hours as 0.51, 0.48, 0.57, 0.29, and 0.18 for each respective five years
of the study.25 Lastly, a study of ballet dancers in Norway reported 3.2 injuries per dancer for a
five-month follow-up period.26
Risk factors positively associated with musculoskeletal injury and pain that were reported in
these cohort studies include age24, female sex for overuse injuries and male sex for acute knee
and upper limb injuries23, 24, 27, 28, seasonal timing26, prior injury29, fatigue30, frequency/intensity
of training30, psychological characteristics associated with eating disorders30, dieting30 and
psychosocial coping31. Nonassociated factors included age27, 28, sex25, rank27, 28, stress/tension26,
and feeling of influence on working conditions26. The majority of these studies explored crude
associations and therefore these associations are preliminary in nature and may not be
independently associated with injury. Only two studies made use of multivariable and/or
stratified analysis to determine independent associations with injury.25, 31
1.2.6 Definition of Injury
In their systematic review of the literature, Hincapié et al found that the definition of an “injured
dancer” varied considerably.4 In many studies, no definition was provided, while others
9
restricted their sampling to dancers with compensable injuries by the Worker’s Compensation
Board. Some studies restricted their definition to injuries that required attention by a health care
professional. Overall, Hincapié et al reported that definitions tended to be vague. This vagueness
is illustrated in one study that defined a dance injury as “one that affected the dancer’s dancing in
some way”, or as an event resulting in financial outlay by the company.4 My update to this
review found that the majority of studies did report on their use of a specific definition of
musculoskeletal injury in dancers.8, 11, 12, 31-34 Of those that reported a definition of injury, they
were more uniform than the definitions reported in the previous systematic review incorporating
either a time-loss or functional component to the definition.
The International Association of Dance Medicine and Science’s Standard Measures Consensus
Initiative is in the process of making recommendations on how to measure and define injury.35
Similarly, Bronner et al have proposed a uniform reporting guideline that includes a standardized
definition of injury based on existing reporting systems for athletes.36 The International
Performing Arts Injury Reporting System instrument uses a definition of injury based on time-
loss from dance activity.35 However, Bronner’s proposal calls for a broader definition of injury
that encompasses any physical complaint resulting from dance-related activity.36 Dance UK, a
British organization for dancers, defines injury as “… a physical problem deriving from stress or
other causes to do with performance, rehearsal, training, touring or the circumstances of dance
life, which affects your ability to participate fully in normal training, performance or physical
activity”.37 To date however, there is no consensus of a definition of injury amongst dance health
practitioners and researchers.
While some advancement has been made regarding the definition of injury, we still know little
about how dancers perceive and cope with musculoskeletal injury. No study in the systematic
review, or my update of the review, has reported on professional dancers’ attitudes and
perceptions of injury.4, 22 Knowledge and understanding of injury from the dancers’ perspective
will help to inform both researchers and health care practitioners dealing with dance injuries. A
recent qualitative study of modern dance students, teachers, community dancers, professional
dancers, and former dancers reports that half of the participants defined injury as “something that
stopped them from dancing or from moving normally.” The second most common response was
“an injury caused by a particular type, quantity, or location of pain”, although the two statements
10
were not always mutually exclusive. A minority of the participants defined injury solely as an
acute event accompanied by visual signs such as swelling and bruising.38
1.2.7 Injury Reporting
Few studies have addressed the issue of injury reporting in professional dancers. One cross-
sectional study reported that between 15-30% of dancers who are injured do not seek medical
attention.20 Psychological issues that may cause a dancer to “dance through” or with pain or
injury include the fear of losing a role, losing their job, being considered unreliable, or pressure
by the company to perform rather than cancel a performance.39 A British study reports that only
32% of professional dancers stopped and rested after an injury occurred, with the majority of
dancers continuing to dance as best they could with no rest.17 Of 376 different dance-related
injuries treated by a naprapath employed by the Stora Theatre in Gothenburg over a three year
period, only 20 injuries were officially reported. These non-reported injuries included injuries as
varied as non-specific neck pain to stress fractures.13 In one Swedish study more than half of the
dancers reported that they had worked on several occasions when they felt they should not have
due to injuries, fatigue, or illness.40 For many reasons, dancers may be dancing through or past
what health care providers consider an injury. The issue of non-reporting of injuries is very
important, as it could bias all measures of incidence or prevalence of musculoskeletal injuries in
dancers. More importantly, this could lead to long-term health consequences for injured dancers.
Hincapié et al recommended in their systematic review that further research is needed to
determine how commonly musculoskeletal injury is not being reported by dancers to their
respective dance companies and the reasons dancers are not reporting their injuries.4
1.2.8 Assessment Tools for Musculoskeletal Injury and Pain in Dancers
Hincapié et al identified one study of a diagnostic and assessment tool for musculoskeletal pain
and functional limitation.4, 40 The Self Estimated Functional Inability because of Pain (SEFIP)
questionnaire is a tool developed specifically for dancers based on the Nordic Musculoskeletal
Questionnaire. The SEFIP is a validated questionnaire created specifically for dancers, and has
good agreement with actual pain and dysfunction found on physical examination.40 The SEFIP is
described further in section 2.6.2.
11
1.3 Environmental Scan of Healthcare and Social Programs
I have performed an environmental scan of healthcare and social programs in nine professional
dance companies in Canada, Israel, Denmark, and Sweden by interviewing the artistic and
administrative staff of each company. An environmental scan provides information of internal
and external conditions about an organization.41 Each of these countries has a publicly funded
national healthcare system; however, coverage of care for dance-related injuries varies in each
country as well as in each company. Physiotherapy and other paramedical services are not
covered by the public health system in Ontario. The National Ballet of Canada and the Toronto
Dance Theatre both supply extended health care coverage to their dancers which covers these
services up to a certain amount. Additionally, the National Ballet of Canada has on-site
physiotherapy available at no cost to the dancers and a medical doctor is available on-site one
day each week. Dancers in the Toronto Dance Theatre must receive physiotherapy or other
paramedical services off-site, and then seek reimbursement from their extended health care
insurance.
Israel’s health care system does cover physiotherapy and other paramedical services. The
Batsheva Dance Company and Ensemble (Israel) does not have on-site healthcare, but has a
physiotherapist associated with the company. Visits to this specific physiotherapist are covered
by the company without restriction of number of visits. Additionally, the company provides an
option for each dancer to seek physiotherapy or other paramedical services such as chiropractic
care, massage therapy, or acupuncture from a roster of practitioners up to a maximum of 23
treatments per season. The Kibbutz Contemporary Dance Company (Israel) and its junior
company provide on-site physiotherapy, massage and acupuncture three times a week at no cost
to the dancer.
The Royal Swedish Ballet provides on-site physiotherapy and naprapathic care at no cost to the
dancers. A nurse is available on-site everyday and an orthopedic and ear, nose, and throat
specialist are available on-site one day a week. Dancers may also seek off-site paramedical
treatment up to a limit of 900 Swedish Kroner ($130 CAD) per year. The Cullberg Ballet
(Sweden) does not have on-site care, but pays for all care sought externally for its dancers. Non-
injured dancers are limited to one treatment per week.
12
Denmark provides partial coverage for physiotherapy and paramedical services; however, the
Royal Danish Ballet has the most extensive on-site healthcare available for its dancers of all the
companies I interviewed. Services provided on-site to the dancers at no cost include:
physiotherapy, massage, sports psychology, medical doctor, orthopedic specialist, dietician, and
special “sick classes” for injured dancers. The company will also reimburse 50% of the cost for
off-site treatment if this is approved in advance.
Workers’ compensation coverage varies by country and company as well. The Toronto Dance
Theatre dancers are covered by the provincial Workplace Safety and Insurance Board (WSIB);
however, the National Ballet of Canada dancers are not covered by the WSIB. Dancers in both
companies have long term disability plans provided by the company. Israel has a National
Insurance (Bituach Leumi) which is accessed if the dancer is disabled due to a work related
injury. The Batsheva Dance Company and Kibbutz Contemporary Dance Company additionally
provide their dancers with optional private disability insurance. Scandinavian countries are well
known for their social support programs for injured workers. Swedish dancers are covered by the
national workers’ compensation insurance. It should be noted that non-Swedes working in
Sweden are entitled to the same benefits. The company pays an injured dancer’s salary for two
weeks after which it is paid by the national insurance. Sweden is moving towards a new system
with additional limitations. Dancers’ work injuries in Denmark are also covered by a national
insurance. Similar to Sweden, injuries are reported after two weeks to the national insurance.
Employment security also varies drastically between companies and countries. The Scandinavian
companies again have the strongest employment security. Once a dancer is employed by a
Swedish or Danish dance company for three years, they obtain permanent lifetime employment.
Swedish dancers can then take a leave of absence for up to three years if desired (for example to
work elsewhere) and have guaranteed employment upon return. Swedish and Danish dancers
may retire at the age of 40 with pension. In the Israeli companies, employment is on a season by
season basis, however dancers are employed year round. In the Canadian companies, dancers are
hired seasonally and most are “laid off” in the summer months. No pensions exist for Israeli or
Canadian dancers.
13
1.4 Summary and Rationale
Informed by the systematic review of the dance medicine literature and my update to this
systematic review, it is apparent that information is still lacking in regards to professional
dancers and musculoskeletal injury and pain. Multivariable analysis has rarely been used to
determine the independence of factors associated with injury in professional dancers.
Additionally, very few studies have included or focused on professional modern dancers, who
are also at risk for musculoskeletal injury that might have long-term consequences for their
future health.
A need for information regarding professional dancers’ attitudes and perceptions of injury exists.
Dance health practitioners and researchers have yet to come to a consensus on the definition of a
dance injury. Understanding injury from the dancers’ perspective could inform future research to
better capture all potentially injured dancers and provide a clearer and more comprehensive
picture of dance injuries overall.
Lastly, it is apparent that for many reasons dancers may be wary to report an injury. The
understanding of reasons why dancers may not report an injury can help the development of
future research methodology to provide better prevalence and incidence estimates. The reporting
of injury also may vary between companies and countries with varying levels of social and
medical support for dancers.
With these issues in mind, I undertook an international cross-sectional survey based study of
professional ballet and modern dancers in Canada, Denmark, Israel, and Sweden.
1.5 Primary Objectives and Research Questions
The primary objective of my research is to determine the point prevalence of dance-related
musculoskeletal injury in professional ballet and modern dancers and the factors associated with
these dance-related injuries.
The secondary objectives of my research are:
1. To report the characteristics and patterns of these dance-related injuries.
2. To explore professional dancers’ attitudes and perceptions of injury.
14
3. To assess if professional dancers are not reporting injuries and why they might not report
their injuries.
CHAPTER 2: Methods and Materials
2.1 Study design
This study is a cross-sectional survey of professional ballet and modern dancers in Canada,
Sweden, Denmark and Israel.
2.2 Source population/Setting
Participants were recruited from three professional ballet and six modern dance companies in
Canada, Sweden, Denmark and Israel. Due to the small number of professional dance companies
in each country, I aimed to recruit companies in multiple countries in order to increase sample
size. Working with research and dance contacts in these countries, I approached the directors of
various dance companies with an aim to recruit the largest modern and ballet companies in each
country as part of this convenience sample. Participating ballet companies included the National
Ballet of Canada, the Royal Swedish Ballet and the Royal Danish Ballet. Participating modern
dance companies included the Toronto Dance Theatre (Canada), the Cullberg Ballet (Sweden),
the Batsheva Dance Company (Israel), the Batsheva Ensemble (Israel), the Kibbutz
Contemporary Dance Company (Israel), and the Kibbutz Contemporary Dance Company 2
(Israel). Table 2.1 outlines the total number of dancers eligible for participation in each
company.
The participating companies were chosen as they represent the highest standard of ballet or
modern dance in that country and are recognized as premier companies in each country and
internationally. All three ballet companies are considered the “national” ballet company of the
country and have a full range of classical ballets in their repertoire. In addition, the National
Ballet of Canada and the Royal Danish Ballet have incorporated neoclassical and contemporary
works into their repertoire. The modern dance companies each have a “house” choreographer
and primarily dance works by that choreographer as well as additional repertoire by guest
choreographers.
All the dance companies have very similar workday schedules. This begins with a company class
(1 to 1¼ hours) to prepare for the workday followed by 6 hours of rehearsal on a non-
performance workday. All three ballet companies begin the day with a ballet class while the 15
16
modern companies begin with either a modern or ballet class. Work days on which performances
take place vary slightly with a later start for evening performances and shorter rehearsal times.
Table 2.1 : Number of Eligible Dancers in Each Dance Company Number of Eligible Dancers
Ballet Companies:
National Ballet of Canada 69
Royal Swedish Ballet 67
Royal Danish Ballet 83
Modern Dance Companies:
Toronto Dance Theatre 16
Cullberg Ballet 20
Batsheva Dance Company 20
Batsheva Ensemble 15
Kibbutz Contemporary Dance Company 17
Kibbutz Contemporary Dance Company 2 12
Total Number Eligible Dancers: 319 Eligible = employed by dance company at time of study, age ≥18, not on leave of absence to dance in another company (only Scandinavian companies), not character dancer. See section 2.3 for further detail.
17
2.3 Inclusion/Exclusion Criteria
Any dancer employed by the participating dance companies at the time of data collection was
eligible to participate with the exclusion of dancers younger than eighteen years of age due to
issues of consent. Dancers who had taken an extended leave of absence to dance in another
company and were not presently dancing with their company were also excluded. This would
only be an issue in the Scandinavian companies where dancers are able to take a three year leave
of absence in order to dance with another company while maintaining their employment status
with the original dance company. The company management was instructed not to forward a
questionnaire to these dancers. Character dancers were also excluded as their work hours and
current dance exposure is very different than the other dancers. Character dancers often are older
dancers in ballet companies and have roles with more mime and gesture type of movements,
rather than the strenuous dance of the other company members.
2.4 Recruitment/Survey Methodology
A date for survey distribution was arranged with the company management. A common time in
the season for data collection was not possible to arrange due to the complex touring and
performing schedules of all companies involved. Companies were instead asked to arrange a
time for the survey distribution which would occur during a period in which performances were
taking place and that did not occur immediately after vacations or holidays. This was done in
order to make the dance exposure as uniform as possible with various companies and repertoires.
Additionally, company managers and directors had noted that performance periods seemed to be
the periods in which more dancers were injured. To encourage participation, a 45-minute time
for survey completion was scheduled during the regular workday in which all dancers would be
present. This eased the burden on the dancers as it took place either after company class or after
a rehearsal which involved all the dancers.
A brief explanation of the purpose of the study as well as the informed consent process took
place prior to the distribution of the survey. Neither company management nor artistic personnel
were present during the survey distribution, so dancers would not feel pressured to participate.
The company management was not aware of which dancers did or did not participate in the
study. One investigator who was familiar with the study and spoke the native language of the
country was present to clarify any questions. All dancers received a study package that included
18
a study questionnaire, an introductory letter and a pre-stamped addressed envelope. Participation
was voluntary and the dancers were instructed not to write any identifying information on the
questionnaire. Dancers were given the option to complete the survey during the time provided or
at their own convenience. Upon completion, they were asked to seal their completed
questionnaire in the provided envelope and return it to a locked drop box on site or by post. All
dancers not present on the day of the survey were forwarded a study package by the company to
ensure that dancers who were off work due to illness or injury would have the opportunity to
participate. Bulletin board and/or email reminders were utilized to remind dancers who had not
yet responded to return the survey to the drop box or by post.
2.5 Description and Pilot-Testing of the Questionnaire
2.5.1 Description of the study questionnaire
The study questionnaire (Appendix 2) consists of two parts. The first part is the Self Estimated
Functional Inability because of Pain (SEFIP) questionnaire. It is the only published tool
developed and validated specifically to measure musculoskeletal pain and function in dancers.40
The second part consists of five sections (A-E). Section A consists of 7 items dealing with
current dance-related pain, injury, and treatment and includes Numeric Rating Scales (NRS).
Section B contains 7 items dealing with the effect and burden of dance-related pain over the past
six months. Section C contains 9 attitudinal questions regarding dancers’ perception of
musculoskeletal injury and one question regarding their current injury status. Section D contains
11 items specific to the dancers’ current injury. Lastly, section E consists of 16 demographic
questions.
2.5.2 Pilot-testing of the study questionnaire
The development and pilot-testing of the study questionnaire was performed prior to my
enrollment at the University of Toronto and therefore is not an official component of my thesis.42
However, a brief description of the process is essential. The study questionnaire was developed
and pilot-tested using standard questionnaire development methodology.43 An environmental
scan and literature review was performed. The pilot questionnaire was evaluated by two
epidemiologists with expertise in survey development for face validity. An expert in dancers’
health evaluated the questionnaire for face and content validity and to ensure the questionnaire’s
applicability in an international setting. The survey was also evaluated by one dance company
19
manager and one rehearsal director in Israel to ensure the information would be useful and
relevant to primary stakeholders. The questionnaire was then pilot-tested on nine dancers from
the National Ballet of Canada. Twenty-two percent of the items needed revision or clarification
based on incorrect answers, absent answers, or written feedback from the dancers. All
ambiguous, problematic or double-barreled questions were identified and revised by consensus
amongst the thesis committee members. Discussion with the participating dance companies
revealed that the working language in each company was English. Therefore, I decided to
administer the questionnaire only in English. The revised questionnaires were sent to co-
investigators in Sweden, Denmark and Israel. These investigators were requested to provide
further input and identify any questions or words that may be confusing. Therefore cross-cultural
face validation was achieved by addressing these issues. A specific questionnaire was developed
for each distinct country. All questions were the same, however country specific units (i.e.
currency) and translations in parentheses were provided for words which were identified as
potentially confusing by the coinvestigator for that country.42
2.6 Measurement and Definition of Variables
2.6.1 Sociodemographic variables
Sociodemographic variables from the study questionnaire used to describe the study population
and to estimate their association with dance injury include: age, sex, height, weight, and before-
tax yearly or monthly income (Appendix 2 Section E). Body mass index (BMI) was calculated
from the height and weight variables using the formula: BMI = kg/m2. Low BMI levels were
defined as <18.5 based on Canadian Guidelines for Body Weight Classification in Adults.44
Low-income cut-offs were obtained or calculated from the official statistical authority of each
country. Low income cut-off points defined for each country are: Canada, <20,778 Canadian
Dollars/year45; Sweden, <140,400 Swedish Krona/year (20,140 CAD)46; Denmark, <100,000
Danish Krone/year (20,310 CAD)47; Israel, <3,710 Israeli New Shekel/month (1,025 CAD)48.
Dance specific characteristics are: number of years in present dance company, number of years
dancing professionally, number of years dancing total, and rank in the company (Appendix 2
Section E). Number of years dancing professionally was defined as: the dancer received payment
for work as a dancer either in a dance company or freelance. Number of years dancing total was
defined as: dance training at least three times per week plus professional experience.
20
2.6.2 The Self-Estimated Functional Inability because of Pain (SEFIP) Questionnaire
The SEFIP is the only validated diagnostic and assessment tool for dancers
identified in the dance medicine literature.4, 40 The SEFIP is an English language questionnaire
based on the Nordic Musculoskeletal Questionnaire and measures the intensity of current pain as
well as ability to dance on a 5-point scale for 14 distinct body regions40. These points are: 0 =
“very well”; 1 = “some pain but not much problem”; 2 = “pretty much pain but I can handle it”;
3 = “much pain, must avoid some movements”; 4 = “cannot work in the production because of
pain”. The SEFIP was validated by Ramel et al using a test-battery for pain and muscular
dysfunction designed for dancers.40 Overall good agreement was demonstrated between the
SEFIP and the test-battery. The mean agreement was 88% with a range of 75% (hips) to 96%
(neck) and a mean kappa value of 0.69. The sensitivity and the specificity were calculated for
each body region. The mean sensitivity and specificity of the SEFIP over the body regions is
72% and 86% respectively. This rises to 86% and 88% respectively if shins, elbows and wrists
were excluded. The authors concluded that any dancer with a score of 2 or greater should be
referred for physical examination by a healthcare practitioner. Of the 14 body regions with an
intensity of 3 or more in Ramel’s work, 13 were found to have positive findings in the test
battery. Ramel et al additionally report that of the 31 painful areas without positive findings in
the test battery, only one of these had a SEFIP score of 3, while seven had a SEFIP score of 2,
and 23 had a SEFIP score of 1.40
The SEFIP is scored on a scale of 0 – 4 for each body region (Appendix 2, Page 106). The
authors also suggest that a sum score may be reported to look at a company’s overall
musculoskeletal pain and function burden at different time periods. One would add all the body
regions to obtain a score out of 64 points for each dancer using a maximum score of 4 for 16
body regions.40 However, as I was not repeating the test for each company, I have chosen not to
report a sum score, but to focus on the individual scores for each body part. This is essential as a
dancer may have a very high score in one body region, but an overall low sum score. A score of
3 represents significant pain accompanied by functional modification of movement. I have
therefore chosen to report SEFIP scores of 3 or more in order to reflect the percentage of dancers
with a functional component associated with their dance-related pain. Additionally, I use a
SEFIP score of 3 or more as an additional or alternative outcome measure of injury prevalence in
addition to self-reported injury.
21
2.6.3 Eleven-point Numerical Rating Scale (NRS-11)
The Eleven-point Numerical Rating Scale (NRS-11) was used to measure average dance-related
pain over the last week (Appendix 2, Section A). This scale is valid and reliable.49, 50 Cut-points
of four and seven were used to differentiate between “mild”, “moderate”, and “severe” pain.50
2.6.4 Current Treatment and Pain Medication Use
Dancers were asked whether they are currently receiving treatment, the type of practitioner they
are receiving care from, and if their treatment was on or off-site. Dancers were additionally
asked to report on their use of prescription and non-prescription pain medication in the past week
for dance-related pain (Appendix 2, Section A).
2.6.5 Injury Status/ Self Reported Injury
I have used Bronner’s definition of injury, “any physical complaint sustained by a dancer
resulting from company performance, rehearsal, or technique class, irrespective of the need for
medical attention or time-loss from dance activities” as a working definition of injury for the
purposes of this study.36 The pilot study indicated that dancers had difficulty reporting
themselves as solely either “injured” or “not injured”.42 I have therefore evaluated dancers’
perception of their injury status by asking them to choose from the following variables:
“injured”, “recovering from an injury”, “suffering from a persistent injury”, or “not injured”
(Appendix 2, Section C). As I was also collecting information regarding dancers’ attitudes and
perceptions of injury, I purposefully did not define injury for them. This qualitative information
will be analyzed in a future paper and asks about definitions of injury in open-ended questions.
For the purposes of this study, any dancer choosing “injured”, “recovering from an injury”, or
“suffering from a persistent injury” will be considered “injured” and reported as self reported
injury (SRI).
2.6.6 Injury Characteristics
Variables chosen as injury characteristics include: dance or non-dance related injury, duration of
injury, severity of injury, time-off due to injury, previous injury occurrence, and time of previous
injury occurrence (Appendix 2, Section D). These injury characteristics have been measured for
self-reported injury.
22
2.6.7 Injury Reporting
Dancers with self-reported injury were asked if they have reported their injury and if so, to
whom they have reported their injury. Those dancers that did not report their injury were asked
to indicate why they did not report their injury. They were given the choice of specific reasons
why they had not reported their injury (Appendix 2, Section D).
2.6.8 Dancers’ Attitudes and Perception of Injury
Dancers were asked to respond to nine attitudinal questions regarding injury. They were asked if
they considered themselves injured in relation to pain, functional changes, time-loss from work
and other possibilities (Appendix 2, Section C). After each statement, options available are:
strongly agree, agree, mildly agree, mildly disagree, disagree, and strongly disagree.
2.6.9 Contextual Company Information
This information was collected in the environmental scan in meetings with the artistic and
administrative staff of each participating company. The information that was collected common
to each company includes: number of dancers in the company, number of performances per year,
number of productions per year, if daily company class is required, if onsite treatment is
available, number of weeks of vacation per year, if the dancers are unionized, if the company
provides “sick classes” for injured dancers, and if the company dances on a raked stage.
2.7 Ethics
Ethical approval for the study protocol was obtained from the research ethics boards of:
University Health Network (Toronto, Canada), the University of Toronto (Toronto, Canada),
Lund University (Lund, Sweden), University of Southern Denmark (Odense, Sweden), and
Hadassah Hospital (Jerusalem, Israel). Ethics board approvals are located in Appendix 3.
23
2.8 Statistical Analysis
2.8.1 Data entry, double data entry, and data cleaning
Data was entered into SPSS 15.0 for Windows. Data cleaning was performed by manual
inspection and frequency analysis of variables. Outlying, unusual, or missing entries were
checked with the original questionnaires and corrected if necessary. Thirteen percent double data
entry was performed and an error rate was calculated using Statistical Analysis Software (SAS)
proc compare function.
2.8.2 Descriptive Statistics
Means with standard deviations and medians are used to describe the distribution of continuous
variables. I have additionally reported minimum and maximum scores for the NRS-11 to
describe the range of dance-related pain over the past week. Frequency and proportions in form
of percentages are reported for categorical data.
2.8.3 Prevalence of Dance-related MSK Injury
I have chosen to use two distinct outcomes to estimate the prevalence of dance-related MSK
injury:
Outcome 1: Self Reported Injury (SRI). To be reported as injured, the dancer had to choose that
they were injured, recovering from an injury, or suffering from a persistent injury.
Outcome 2: SEFIP score ≥3. In this analysis the dancer was defined as injured if they had a
SEFIP score ≥3 for any body region. This definition has a functional component (modifying
movement in order to dance).
To estimate self-reported injury prevalence, all non-dance related injuries were removed. The
options “injured”, “recovering from an injury”, and “suffering from a persistent injury” were
collapsed to form the numerator. The denominator for the self reported injury prevalence
estimate was the total number of dancers who responded to that specific question. This is
reported by dance company and style. I have reported 95% confidence intervals for the self-
reported injury point prevalence estimates.
24
To estimate SEFIP ≥3 injury prevalence, the number of distinct dancers with at least one body
region score of three or more was used for the numerator. The denominator was the total number
of dancers who responded to the SEFIP. This is reported by dance company and style. I have
reported 95% confidence intervals for the SEFIP ≥3 injury prevalence estimates.
2.8.4 Factors associated with MSK-injury in professional dancers
Logistic regression using Statistical Analysis Software 9.1 was performed to determine which
variables are associated with injury. Logistic regression is an appropriate statistical test when the
dependent variable is dichotomous as it is in this situation: “injured” or “not injured”.51, 52 Two
separate analyses were performed using the two different outcomes for “injury”. These are self-
reported injury and SEFIP score ≥3. The choice of variables to include in the analysis was
informed by the literature review. The independent variables analyzed are: sex, low body weight,
style of dance, low income, company, country, number of years dancing professionally, number
of years dancing total, age, number of years in present company, and rank (ballet only). The
continuous variables “number of years dancing total”, “number of years dancing professionally”,
“number of years dancing in the present company”, and “age” were highly skewed, therefore
quartiles were derived.
A preliminary univariate analysis was performed separately for ballet dancers and modern
dancers. Any variables with a p-value of less than 0.25 were then included in the multivariable
models. Backwards stepwise regression was then performed on these models and items with a p-
value greater than 0.10 were removed from the model. The strength of the association of each
variable with self reported injury and SEFIP score ≥3 is reported in the form of odds ratios with
95% confidence intervals.
CHAPTER 3: Results
3.1 Response rate Response rates by company are presented in Table 3.1. The response rates for ballet companies
were very similar with an overall response rate of 81%. The response rates for modern dance
companies ranged between 65 to 100% with an overall response rate of 82%. Two companies
had response rates lower than 80 percent. The reason for the lower response rates in the Kibbutz
Contemporary Dance Company and the Kibbutz Contemporary Dance Company 2 is most likely
due to difficult working conditions on the day the survey was scheduled. Survey distribution
took place after a technical run in a new studio without a proper ventilation system on a day of
extreme heat.
Table 3.1: Response rates Company # of participants # of dancers Response Rate (%)Ballet Companies: National Ballet of Canada 55 69 80 Royal Swedish Ballet 55 67 82 Royal Danish Ballet 68 83 82 Total Ballet Dancers 178 219 81 Modern Companies: Toronto Dance Theatre 14 16 88 Cullberg Ballet 16 20 80 Batsheva Dance Company 18 20 90 Ensemble Batsheva 15 15 100 Kibbutz Contemporary Dance Company 11 17 65 Kibbutz Contemporary Dance Company 2 8 12 67 Total Modern Dancers 82 100 82
25
26
3.2 Data entry error rate
The total number of discreet variables entered into the statistical software was 156 for 266 study
participants. A 13% double data entry was performed and 19 entry errors were identified. This
resulted in an error rate of 0.3%. These errors were corrected.
3.3 Sociodemographic characteristics of the study population
The sociodemographic characteristics of age, sex, marital status, and income are reported in
Table 3.2. Dancers in the Scandinavian companies (Royal Swedish Ballet, Royal Danish Ballet,
and Cullberg Ballet) are slightly older. The two junior companies (Ensemble Batsheva and
Kibbutz Contemporary Dance Company) are younger due to the nature of these companies.
There were more female participants than male participants in all three ballet companies.
Overall, 58% of ballet dancers were female. Male to female ratio of participants varied in the
modern dance companies and led to an overall equal percentage of male and female participants
when combined. Higher percentages of reported income below the low income cut-off were
reported in both Canadian companies (National Ballet of Canada and Toronto Dance Theatre) as
well as the Kibbutz Contemporary Dance Company 2.
The characteristics of body mass index and low body weight, as well as exposure to dance
(number of years dancing) are presented in Table 3.3. Mean body mass index is lowest in the
female National Ballet of Canada dancers; however, all three ballet companies had percentages
of females with low body weight approaching or greater than 50%. Scandinavian dancers (ballet
and modern) had the longest mean years dancing professionally and years dancing total.
Position or rank in the company was not reported in table format due to the differences in
ranking between companies. All ballet companies use a hierarchal ranking system consisting of
apprentice, corps de ballet, soloist and principal dancers. The Royal Swedish Ballet however,
does not have any apprentice dancers. Of the National Ballet of Canada participants, 7(12.7%)
were apprentices, 25(45.5%) were in the corps de ballet, and 23(41.8%) were soloists or
principal dancers. Of the Royal Swedish Ballet participants, 33(61.1%) were in the corps de
ballet and 21(38.9%) were soloist or principal dancers. Of the Royal Danish Ballet participants,
4(5.9%) were apprentices, 39(57.4%) were in the corps de ballet, and 25(36.8%) were soloist or
principal dancers. The Cullberg Ballet, the Batsheva Dance Company, and the Kibbutz
27
Contemporary Dance Company do not have any ranking system. The Toronto Dance Theatre
has full and junior company members as well as apprentices. Of the Toronto Dance Theatre
participants, 10(71.4%) were full company members, 2(14.3%) were junior company members
and 2(14.3%) were apprentices. The Batsheva Ensemble and the Kibbutz Contemporary Dance
Company 2 do not have a ranking system, but do have apprentices in the company. Of the
Batsheva Ensemble dancers, 1(6.7%) participant was an apprentice. Of the Kibbutz
Contemporary Dance Company 2 dancers, 1(12.5%) participant was an apprentice.
The percentage of dancers whose origin is from the country where the dance company is located
is reported in Table 3.4. The Cullberg Ballet had the lowest percentage of dancers from the
country where the company is located (31.3%) while the Kibbutz Contemporary Dance
Company 2 had the highest frequency (100.0%). In order not to identify specific dancers in each
company, the country of origin of all dancers is not broken down by company. Besides Canada,
Sweden, Denmark and Israel, dancers from the following countries participated in the study:
Armenia, Australia, Austria, Belarus, Belgium, Brazil, Bulgaria, China, England, Finland,
France, Germany, Hungary, Iceland, Italy, Japan, Lithuania, Mexico, New Zealand, Norway,
Philippines, Poland, Russia, Scotland, Serbia, South Africa, Spain, Switzerland, USA, and
Zambia.
Table 3.2: Sociodemographic characteristics of participating dancers: age, sex, marital status, and low-income cut-offs.
Ballet Companies
Modern Dance Companies
Demographic
NBC n=55
RSB n=55
RDB n=68
TDT n=14
CUL n=16
BAT n=18
ENS n=15
KDC n=11
KDC2 n=8
Age in years mean(SD),med
26(5.4),25
30(6.3),30
27(6.1),26
26(4.8),26
30(4.7),30
27(3.4),27
22(2.1),23
25(4.2),25
21(0.8),21
Sex: n(%) Female
29(52.7)
35(64.8)
40(58.8)
6(42.9)
8(50.0)
9(50.0)
7(46.7)
8(72.7)
3(37.5)
Marital status: n(%) Never married Married Common law Divorced Widowed
31(56.4)
12(21.8) 6(10.9)
5(9.1) 1(1.8)
22(41.5)
14(26.4) 16(30.2)
1(1.9)
0
48(77.4)
10(16.1) 3(4.8)
1(1.5)
0
13(92.9) 0
1(7.1) 0 0
12(75.0)
2(12.5) 2(12.5)
0 0
11(61.1)
1(5.6) 5(27.8)
1(5.6)
0
14(93.3)
1(6.7) 0 0 0
11(100) 0 0 0 0
8(100) 0 0 0 0
Income below low income cut-off*: n(%)
8(14.5)
2(4.0)
1(1.5)
7(50.0)
0
0
1(6.7)
0
8(100.0)
Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2; SD, Standard deviation; Med, Median;BMI, Body Mass Index. *Low income cut-offs: Canada, <20,778 Canadian Dollars/year; Sweden, <140,400 Swedish Krona/year; Denmark, <100,000 Danish Krone/year; Israel, <3,710 Israeli New Shekel/month.
28
29
Ballet Companies
Modern Dance Companies
NBC n=55
RSB n=55
RDB n=68
TDT n=14
CUL n=16
BAT n=18
ENS n=15
KDC n=11
KDC2 n=8
BMI: males mean(SD), med
22.2(1.2),
22.4
22.5(1.6),
22.5
22.2(1.3),
21.8
22.2(1.1),
22.2
22.4(1.7),
22.0
22.2(2.2),
21.8
20.5(2.0),
20.6
20.6(1.0),
21.1
22.2(2.5),
20.9 BMI: females mean(SD), med
18.2(0.9),
18.1
18.7(1.1),
18.6
18.5(0.9),
18.4
21.3(2.0),
21.2
20.7(1.4),
20.8
20.4(1.3),
20.1
20.1(1.9),
19.7
19.7(0.9),
19.4
20.2(0.6),
20.3 Low body weight males*: n(% of males)
0
0
0
0
0
0
1(12.5)
0
0
Low body weight females*: n(% of females)
21(72.4)
17(48.6)
19(47.5)
0
0
0
1(14.3)
1(12.5)
0
Exposure: mean(SD),med Years in company
6.7(5.4),5.0
9.2(7.0),7.5
8.8(6.0),7.0
4.8(3.4).3.5
4.6(5.2),2.5
7.0(2.3).7.0
1.9(0.9),2.0
4.2(3.5),3.0
1.3(0.5),1.0
Years dancing professionally
8.1(5.8),7.0
12.4(6.7),
13.0
9.7(6.4),8.0
5.3(4.0).4.0
11.2(6.1),
9.5
8.6(2.8),9.0
3.2(1.7),3.0
5.7(3.1),5.0
2.1(1.5),1.5
Years dancing total
16.0(5.7),
15.0
20.7(6.8),
20.5
17.3(7.3),
16.0
13.4(6.4),
12.0
19.0(6.1),
18.5
15.7(5.2),
15.0
9.5(5.0),8.0
15.2(6.1),
15.0
7.6(2.9),7.5
Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2; SD, Standard deviation; BMI, Body Mass Index. Low body weight defined as BMI <18.5.
Table 3.3: Characteristics of participating dancers: Body Mass Index, low body weight, and years dancing.
30
Table 3.4 Country of Origin Company Name (Country) Dancers Originating from Country of
Dance Company n(%)
National Ballet of Canada (Canada)
30(54.5)
Royal Swedish Ballet (Sweden)
27(50.0)
Royal Danish Ballet (Denmark)
37(54.4)
Toronto Dance Theatre (Canada)
11(78.6)
Cullberg Ballet (Sweden)
5(31.3)
Batsheva Dance Company (Israel)
12(66.7)
Ensemble Batsheva (Israel)
10(66.7)
Kibbutz Contemporary Dance Company (Israel)
8(72.7)
Kibbutz Contemporary Dance Company 2 (Israel)
8(100.0)
3.4 Self Estimated Functional Inability because of Pain (SEFIP) scores
Dancers with SEFIP scores ≥3 are reported in Table 3.5. I have chosen to report
percentages of scores of 3 or greater, as a score of 3 denotes some degree of functional
impairment (“Much pain, must avoid some movements”). Thus, the SEFIP scores can
provide a snapshot of the companies’ musculoskeletal health regarding both pain and
function for each body region.
Ballet companies’ SEFIP scores followed similar patterns (Table 3.5). When companies
were combined, ballet dancers reported highest percentage of SEFIP scores ≥3 for ankles
and feet followed by low back, hips, and knees (Table 3.6). This pattern was similar for
both males and females. Slight differences did exist between ballet companies for body
areas outside of these four most frequent reported problematic regions. The National
Ballet of Canada had a higher frequency of SEFIP scores ≥3 for the calf region (5.5%)
31
compared to the Royal Swedish Ballet (1.8%) and the Royal Danish Ballet (0). The
National Ballet of Canada had no reported SEFIP scores ≥3 for the mid-back region
compared to the Royal Swedish Ballet (3.6%) and the Royal Danish Ballet (6.9%). The
posterior thigh region differed between males (1.4%) and females (4.9%) with the
majority of these scores occurring in the Royal Swedish Ballet with 9.1% of the dancers
having SEFIP scores ≥3 for the posterior thigh region. Overall, the frequency of SEFIP
scores ≥3 for the upper limb in ballet dancers was very low. Only the dancers in the RDB
reported any SEFIP scores ≥3 for the shoulder (2.7%) and the wrist hand regions (1.4%).
No ballet dancers reported SEFIP scores ≥3 for the elbows or the anterior thigh regions.
In contrast to ballet dancers, modern dancers’ body region with the highest percentage of
SEFIP scores ≥3 varied between modern dance companies (Table 3.5). The shoulder
region was highest for the Toronto Dance Theatre dancers (21.4%). The low back region
was highest for the Cullberg Ballet (25.1%), Kibbutz Contemporary Dance Company
(27.3%) and Kibbutz Contemporary Dance Company 2(37.5%) dancers. Toes were
equally as problematic for the Kibbutz Contemporary Dance Company 2 dancers. The
neck was the most problematic region for the Batsheva Dance Company dancers (22.3%).
The Ensemble Batsheva dancers had equal problems with low back, hips, shoulders,
wrist/hand, and ankles/feet (6.7%). No male modern dancers reported SEFIP scores ≥3
for the neck compared to 12.2% of females (Table 3.6). Male modern dancers did report
SEFIP scores ≥3 for the wrist/hand (4.9%) and the shin (4.9%) regions while no females
reported SEFIP scores ≥3 in these regions. No modern dancers reported SEFIP scores ≥3
for the anterior thigh or calf regions.
Table 3.5: Frequency of SEFIP scores ≥ 3 (by company) Location
NBC n=55 n(%)
RSB n=55 n(%)
RDB n=68 n(%)
TDT n=14 n(%)
CUL n=16 n(%)
BAT n=18 n(%)
ENS n=15 n(%)
KDC n=11 n(%)
KDC2 n=8 n(%)
Neck
1(1.8) 1(1.8) 0 1(7.1) 0 4(22.3) 0 0 0
Mid-Back
0 2(3.6) 5(6.9) 1(7.1) 1(6.3) 0 0 1(9.1) 1(12.5)
Elbows
0 0 0 1(7.1) 0 0 0 0 0
Lower Back
3(5.5) 5(9.1) 8(11.0) 1(7.1) 4(25.1) 2(11.2) 1(6.7) 3(27.3) 3(37.5)
Hips
5(9.1) 5(9.1) 3(4.4) 0 1(6.3) 3(16.7) 1(6.7) 1(9.1) 0
Posterior Thighs
0 5(9.1) 1(1.4) 0 0 0 0 1(9.1) 0
Shoulders
0 0 2(2.7) 3(21.4) 0 1(5.6) 1(6.7) 0 0
Wrists/hands
0 0 1(1.4) 0 0 1(5.6) 1(6.7) 0 0
Anterior Thighs
0 0 0 0 0 0 0 0 0
Knees
3(5.5) 6(10.9) 4(5.9) 0 2(12.5) 0 0 1(9.1) 0
Shins
1(1.8) 0 0 0 0 0 0 0 2(25.0)
Calves
3(5.5) 1(1.8) 0 0 0 0 0 0 0
Ankles/feet
9(16.4) 11(20.0) 8(11.0) 1(7.1) 1(6.3) 3(16.7) 1(6.7) 1(9.1) 0
Toes 2(3.6) 2(3.6) 1(1.4) 0 1(6.3) 1(5.6) 0 1(9.1) 3(37.5) Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain; NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2.
32
33
Table 3.6: Frequency of SEFIP scores ≥ 3 (by style, sex)
Ballet
Modern
Location Male n=73 n(%)
Female n=103 n(%)
Male n=41 n(%)
Female n=41 n(%)
Neck
1(1.4) 1(1.0) 0 5(12.2)
Mid-Back
2(2.8) 5(4.9) 3(7.3) 1(2.4)
Elbows
0 0 0 1(2.4)
Lower Back
6(8.2) 9(8.7) 5(12.2) 6(14.6)
Hips
4(5.5) 7(6.8) 3(7.3) 3(7.3)
Posterior Thighs
1(1.4) 5(4.9) 0 1(2.4)
Shoulders
1(1.4) 0 3(7.3) 2(4.9)
Wrists/hands
0 1(1.0) 2(4.9) 0
Anterior Thighs
0 0 0 0
Knees
4(5.5) 4(4.0) 1(2.4) 2(4.9)
Shins
0 1(1.0) 2(4.9) 0
Calves
1(1.4) 3(2.9) 0 0
Ankles/feet
11(15.1) 17(16.3) 4(9.8) 3(7.3)
Toes 1(1.4) 4(3.9) 3(7.3) 3(7.3) Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain
34
3.5 Numeric Rating Scale Scores: Dance related pain over the last week.
Descriptive results of the NRS-11 scores of dance related pain over the last week are
presented in Table 3.7. Mean scores for ballet and modern dancers were similar, with
ballet dancers reporting a mean score of 4.3 (2.3 SD) average pain over the last week and
modern dancers reporting a mean score of 4.5 (2.0 SD) average pain over the last week.
Dancers reported scores at all levels of the scale including both extremes of 0 (no pain) as
well as 10 (worst possible pain). Overall, the majority of dancers are reporting some
degree of pain. The frequency of pain by cut-points along the NRS-11 scale is presented
in Table 3.8. Higher frequencies of ballet dancers are reporting scores of “no pain” than
modern dancers; however, no modern dancers reported NRS-11 scores higher than 8.
Ballet dancers in two companies reported scores of “worst possible pain” (Table 3.7).
Overall, the majority of dancers are reporting pain in the range of 1-4 (mild) followed by
5-7 (moderate), 8-10 (severe), and “no pain” ranges respectively. Two exceptions
occurred in the Toronto Dance Theatre and the Kibbutz Contemporary Dance Company
where dancers reported higher frequencies of pain in the 5-7 range (moderate) followed
by the 1-4 (mild), 8-10 (severe), and “no pain” ranges respectively.
35
Table 3.7: Average dance-related pain over last week, Numeric Rating Scale-11 scores
Mean Median SD Minimum-Maximum Ballet dancers(n=176)
4.3 4.0 2.3 0-10
National Ballet of Canada(n=55) 4.7 5.0 2.0 0-10 Royal Swedish Ballet(n=55) 4.3 3.0 2.6 0-9 Royal Danish Ballet(n=67) 3.9 3.0 2.3 0-10
Modern dancers(n=82)
4.5 5.0 2.0 0-8
Toronto Dance Theatre(n=14) 5.1 5.0 1.9 1-8 Cullberg Ballet(n=16) 3.8 3.0 2.0 1-8 Batsheva Dance Company(n=18) 4.0 3.5 2.0 1-8 Ensemble Batsheva (n=15) 4.3 4.0 1.8 2-7 Kibbutz Contemporary Dance Company(n=11)
5.0 6.0 2.3 0-8
Kibbutz Contemporary Dance Company 2 (n=8)
6.0 6.0 1.4 4-8
Abbreviations: SD, Standard deviation.
36
Table 3.8: Pain severity using Numeric Rating Scale-11 cut-points. Average dance-related pain over last week.
NRS-11 score: {0} {1-4} {5-7} {8-10} n(%) n(%) n(%) n(%) Ballet dancers (n=176) 8(4.5) 93(52.9) 61(34.7) 14(7.9) National Ballet of Canada (n=55) 1(1.8) 25(45.4) 25(45.4) 4(7.3) Royal Swedish Ballet (n=55) 4(7.3) 26(38.3) 19(34.5) 6(10.9) Royal Danish Ballet (n=67) 4(6.0) 42(62.8) 17(25.4) 4(6.0) Modern dancers (n=82) 1(1.2) 39(47.6) 37(45.1) 5(6.1) Toronto Dance Theatre (n=14) 0 5(35.6) 8(57.1) 1(7.1) Cullberg Ballet (n=16) 0 11(68.9) 4(25.1) 1(6.3) Batsheva Dance Company (n=18) 0 11(61.1) 6(33.4) 1(5.6) Ensemble Batsheva (n=15) 0 9(60.0) 6(40.0) 0 Kibbutz Contemporary Dance Company (n=11) 1(9.1) 2(18.2) 7(63.7) 1(9.1) Kibbutz Contemporary Dance Company 2 (n=8) 0 1(12.5) 6(75.0) 1(12.5) Abbreviations: NRS, Numeric Rating Scale. Categories based on cut points50: {0}= no pain, {1-4}= mild, {5-7}= moderate, {8-10}= severe
37
3.6 Current treatment The majority of dancers reported they were currently receiving treatment for dance-
related pain (Table 3.9). Dancers in the TDT were the only group in which less than 50%
of dancers reported currently receiving treatment for their dance-related pain. The types
of healthcare practitioners that these dancers were receiving care from are reported in
Table 3.10 and in aggregate format by style in Table 3.11. Some types of healthcare
utilized by dancers are country dependent. Naprapaths were utilized only by Swedish
dancers. Osteopaths were utilized by Swedish and Danish dancers. Athletic therapists
were utilized by Canadian and Swedish ballet dancers. Israeli dancers did not utilize
chiropractic care. The majority of ballet and modern dancers receiving treatment are
utilizing massage therapy and physiotherapy followed by acupuncture. Very few ballet
dancers and no modern dancers were receiving treatment from a medical doctor for
dance-related pain. Where dancers are receiving treatment is detailed in Table 3.12.
Modern dancers are more likely to solely receive care off-site than ballet dancers with the
exception of the KDC and KDC2 dancers.
38
Table 3.9: Dancers currently receiving treatment for dance-related pain.
Dancers Currently Receiving Treatment
n(%)
Ballet dancers (n=177)
108(61.0)
National Ballet of Canada (n=55) 33(60.0) Royal Swedish Ballet (n=55) 35(63.6) Royal Danish Ballet (n=68) 40(58.8) Modern dancers (n=82)
60(73.2)
Toronto Dance Theatre (n=14) 6(42.9) Cullberg Ballet (n=16) 9(56.3) Batsheva Dance Company (n=18) 16(88.9) Ensemble Batsheva (n=15) 10(66.7) Kibbutz Contemporary Dance Company (n=11)
11(100.0)
Kibbutz Contemporary Dance Company 2 (n=8)
8(100.0)
39
NBC N=33 n(%)
RSB N=35 n(%)
RDB N=40 n(%)
TDT N=6 n(%)
CUL N=9 n(%)
BAT N=16 n(%)
ENS N=10 n(%)
KDC N=11 n(%)
KDC2 N=8 n(%)
Acupuncturist
4(12.1) 9(25.7) 6(15.0) 2(33.3) 1(11.1) 9(56.3) 4(40.0) 5(45.5) 2(25.0)
Athletic Therapist
17(51.5) 2(5.7) 0 0 0 0 0 0 0
Chiropractor
2(6.1) 7(20.0) 2(5.0) 2(33.3) 1(11.1) 0 0 0 0
Massage Therapist
29(87.9) 15(42.9) 25(62.5) 4(66.7) 5(55.6) 6(37.5) 7(70.0) 11(100.0) 7(87.5)
Medical Doctor
3(9.1) 3(8.6) 5(12.5) 0 0 0 0 0 0
Medical Specialist
0 1(2.9) 1(2.5) 0 0 0 0 0 0
Naturopath
2(6.1) 1(2.9) 1(2.5) 1(16.7) 1(11.1) 0 0 0 0
Naprapath
n/a 10(28.6) n/a n/a 1(11.1) n/a n/a n/a n/a
Osteopath
2(5.7) 7(17.5) 0 6(66.7) 0 0 0 0
Physiotherapist
24(72.7) 15(42.9) 28(70.0) 2(33.3) 2(22.2) 12(75.0) 9(90.0) 9(81.8) 7(87.5)
Psychologist/ Psychiatrist/ Counselor
2(6.1) 0 4(10.0) 1(16.7) 2(22.2) 1(6.3) 1(10.0) 0 0
Other 3(9.4) 0 4(10.0) 2(33.3) 1(11.1) 7(43.8) 2(20.0) 1(9.1) 0 Includes only dancers who responded that they were receiving treatment for dance-related pain. Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2; n/a, not applicable.
Table 3.10: Treatment from Healthcare Practitioners (only dancers currently receiving treatment)
40 Table 3.11: Frequency of Treatment from Healthcare Practitioners (only dancers currently receiving treatment)
Ballet N=108 n(%)
Modern N=60 n(%)
Acupuncturist
19(17.4) 23(38.3)
Athletic Therapist
19(17.4) 0
Chiropractor
11(10.1) 3(5.0)
Massage Therapist
69(63.3) 40(66.7)
Medical Doctor
11(10.1) 0
Medical Specialist
2(1.8) 0
Naturopath
4(3.7) 2(3.3)
Naprapath
10(9.2) 1(1.7)
Osteopath
16(14.7) 6(10.0)
Physiotherapist
68(62.4) 41(68.3)
Psychologist/ Psychiatrist/ Counselor
6(5.5) 5(8.3)
Other 7(6.5) 13(21.7)Includes only dancers who responded that they were receiving treatment for dance-related pain.
41
Table 3.12: Site of Current Treatment (only dancers currently receiving treatment)
On-site n(%)
Off-site n(%)
Both n(%)
Ballet (N=107)
49(45.8) 11(10.3) 47(43.9)
National Ballet of Canada (N=34) 11(32.4) 4(11.8) 19(55.9) Royal Swedish Ballet (N=34) 18(52.9) 6(17.6) 10(29.4) Royal Danish Ballet (N=39) 20(51.3) 1(2.6) 18(46.2) Modern (N=59)
19(32.2) 33(55.9) 7(11.9)
Toronto Dance Theatre (N=6) 0 6(100.0) 0 Cullberg Ballet (N=8) 0 7(87.5) 1(12.5) Batsheva Dance Company (N=16) 2(12.5) 10(62.5) 4(25.0) Ensemble Batsheva (N=10) 0 9(90.0) 1(10.0) Kibbutz Contemporary Dance Company (N=11) 9(81.8) 1(9.1) 1(9.1) Kibbutz Contemporary Dance Company 2 (N=8) 8(100.0) 0 0 Includes only dancers who responded that they were receiving treatment for dance-related pain.
42
3.7 Pain Medication Use
Frequency of pain medication use is reported in Table 3.13. Canadian ballet (58.2%) and modern
(50.0%) dancers report higher use of non-prescription pain medications in the past week
compared to other countries. Amongst ballet dancers, the Canadian dancers (20.0%) also
reported the highest frequency of prescription pain medication use. There was one reported use
of prescription pain medication use in modern dancers.
Table 3.13: Pain medication use in last week (all dancers)
Non-prescription pain medication use in last week
n(%)
Prescription pain
medication use in last week n(%)
Ballet dancers (N=175)
69(39.4) 25(14.3)
National Ballet of Canada (n=55)
32(58.2) 11(20.0)
Royal Swedish Ballet (n=53) 20(37.7) 10(18.5) Royal Danish Ballet (n=67) 17(25.4) 4(6.0) Modern dancers (n=82)
18(22.0) 1(1.2)
Toronto Dance Theatre (n=14)
7(50.0) 0
Cullberg Ballet (n=16) 4(25.0) 0 Batsheva Dance Company (n=18)
4(22.2) 0
Ensemble Batsheva (n=15) 0 0 Kibbutz Contemporary Dance Company (n=11)
1(9.1) 1(9.1)
Kibbutz Contemporary Dance Company 2 (n=8)
2(25.0) 0
43
3.8 Injury Prevalence Dancers’ current self-reported injury status is detailed in Table 3.14. Almost ¼ of all dancers are
reporting a persistent injury. Four dancers reported injuries that were not dance-related and have
been removed. The point prevalence of self-reported injury (Outcome 1) is reported with 95%
confidence intervals in Table 3.15. (Non-dance related injuries have been removed from this
table). The aggregate point prevalence of self-reported injury (SRI) for ballet dancers was 54.8%.
This ranged from 47.1% in the Royal Danish Ballet to 59.3% in the Royal Swedish Ballet. The
aggregate point prevalence of SRI for modern dancers is 46.3%. This ranged from 9.1% in the
Kibbutz Contemporary Dance Company to 66.7% in the Batsheva Dance Company.
The point prevalence of SEFIP ≥3 injury (Outcome 2) is reported with 95% confidence intervals
in Table 3.16. The aggregate point prevalence of SEFIP ≥3 injury in ballet dancers is 38.8%.
This ranged from 33.8% in the Royal Danish Ballet to 47.3% in the Royal Swedish Ballet. The
aggregate point prevalence of SEFIP ≥3 injury in modern dancers is 45.1%. This ranged from
20.0% in the Ensemble Batsheva to 100.0% in the Kibbutz Contemporary Dance Company 2.
44 Table 3.14: Current Injury Status
Injured
n(%)
Recovering from an Injury n(%)
Persistent Injury n(%)
Not Injured n(%)
Ballet Dancers (n=177)
17(9.6) 38(21.5) 44(24.9) 78(44.1)
National Ballet of Canada (n=55) 4(7.3) 15(27.3) 13(23.6) 23(41.8) Royal Swedish Ballet (n=54) 7(13.0) 8(14.8) 19(35.2) 20(37.0) Royal Danish Ballet (n=68) 6(8.8) 15(22.1) 12(17.6) 35(51.5) Modern Dancers (n=82)
9(11.0) 11(13.4) 19(23.2) 43(52.4)
Toronto Dance Theatre (n=14) 2(14.3) 0 5(35.7) 7(50.0) Cullberg Ballet (n=16) 2(12.5) 2(12.5) 3(18.8) 9(56.3) Batsheva Dance Company (n=18) 2(11.1) 6(33.3) 4(22.2) 6(33.3) Ensemble Batsheva (n=15) 2(13.3) 3(20.0) 4(26.7) 6(40.0) Kibbutz Contemporary Dance Company (n=11)
0 0 1(9.1) 10(91.9)
Kibbutz Contemporary Dance Company 2 (n=8)
1(12.5) 0 2(25.0) 5(62.5)
45 Table 3.15: Point prevalence of Self Reported Injury
Prevalence of Dance-related MSK Injury %(95%CI)
Ballet dancers (n=177)
54.8 (47.7 – 62.1)
National Ballet of Canada (n=55) 58.2 (45.1 – 71.2) Royal Swedish Ballet (n=54) 59.3 (46.1 – 72.4) Royal Danish Ballet (n=68) 47.1 (35.2 - 58.9) Modern dancers (n=82)
46.3 (35.5 – 57.1)
Toronto Dance Theatre (n=14) 42.9 (16.9 – 68.8) Cullberg Ballet (n=16) 43.7 (19.4 – 68.1) Batsheva Dance Company (n=18) 66.7 (44.9 – 88.4) Ensemble Batsheva (n=15) 60 (35.2 – 84.8) Kibbutz Contemporary Dance Company (n=11)
9.1 (0– 26.1)
Kibbutz Contemporary Dance Company 2 (n=8)
37.5 (3.9 – 71.0)
Table 3.16: Point prevalence of SEFIP≥3 Injury Prevalence of SEFIP≥3 Injury
%(95%CI)
Ballet dancers (n=178)
38.8 (30.9 – 45.1)
National Ballet of Canada (n=55) 36.4 (23.3 – 48.7) Royal Swedish Ballet (n=55) 47.3 (33.8 – 60.2) Royal Danish Ballet (n=68) 33.8 (22.7 – 45.3) Modern dancers (n=82)
45.1 (34.2 – 55.8)
Toronto Dance Theatre (n=14) 35.7 (10.9 – 61.1) Cullberg Ballet (n=16) 31.3 (8.3 – 53.7) Batsheva Dance Company (n=18) 55.6 (33.1 – 78.9) Ensemble Batsheva (n=15) 20.0 (0 – 40.2) Kibbutz Contemporary Dance Company (n=11) 54.5 (25.6– 84.4) Kibbutz Contemporary Dance Company 2 (n=8) 100.0 (100.0 – 100.0)
Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain
46
3.9 Factors associated with self-reported dance-related musculoskeletal injuries (SRI) in dancers.
3.9.1 Univariate analysis (crude analysis)
The results of the univariate analysis for ballet dancers are reported in Table 3.17. The frequency
of injury for each variable considered for the multivariable analysis is reported with associated
odds ratios and 95% confidence intervals. The variables that have met the criteria to be included
in the regression analysis are sex, low body weight, low income, rank, number of years dancing
total, number of years dancing professionally, number of years dancing in present company, and
age. The univariate analyses suggest that females are less likely to report injury than males;
dancers with low body weight are less likely to report injury than dancers with normal body
weight; dancers earning below the low income threshold are less likely to report injury than
dancers above the threshold. Soloist or principal dancers are more likely to report an injury than
corps de ballet dancers whereas apprentices are less likely. Dancers in the three quartiles above
22 years of age were more likely to report an injury than younger dancers in the reference age
group of ≤22 years. Dancers dancing more than three years professionally (all three quartiles)
were more likely to report injury than the reference group of dancers dancing three or fewer
years professionally. Dancers who reported dancing 17-23 years total and ≥24 years total were
more likely to report an injury than dancers who danced ≤11 years total. Dancers who had
danced 7-12 years or ≥13 years in the present company are more likely to report an injury than
those dancers who had danced ≤2 years in the present company. The variables company and
country were not significantly associated with self-reported injury.
The univariate analysis for modern dancers is presented in Table 3.18. The Kibbutz
Contemporary Dance Company dancers were less likely to report an injury than the Toronto
Dance Theatre dancers (OR = 0.10). The variables sex, low body weight, low income, country,
number of years dancing total, number of years dancing professionally, number of years in
present company, and age were not significantly associated with self-reported injury in the
univariate analysis. Due to the fact that no other variables met the criteria for inclusion in the
regression analysis, multivariable analysis was not performed for modern dancers.
47
Table 3.17: Univariate Analysis Results for Self Reported Injury(ballet dancers only) Variable Not injured
n(%) Injured n(%)
OR 95% CI p-value
Sex: Female
52(66.7)
52(52.5)
0.55
0.30 – 1.02
0.06
Age ≤22 years 23-26 years 27-32 years ≥33 years
26(33.3) 20(25.6) 15(19.2) 17(21.8)
16(16.3)25(25.5)27(27.6)30(30.6)
1.00 2.03 2.93 2.87
0.86 – 4.781.21 – 7.101.21 – 6.79
0.10 0.02 0.02
Low body weight (<18.5 BMI)
31(40.3)
26(27.7)
0.57 0.30 – 1.08 0.08
Low income: Below cut-off
9(11.5)
2(2.1)
0.16
0.03 – 0.77
0.02
Rank: Corps Apprentice Soloist/principal
49(62.8) 8(10.3) 21(26.9)
48(48.5)3(3.0)
48(48.5)
1.00 0.38 2.33
0.10 – 1.531.22 – 4.47
0.17 0.01
Number of years dancing total ≤11 years 12-16 years 17-23 years ≥24 years
22(28.6) 21(27.3) 18(23.4) 16(20.8)
16(16.5)22(22.7)30(30.9)29(29.9)
1.00 1.44 2.29 2.49
0.60 – 3.470.96 – 5.471.03 – 6.05
0.42 0.06 0.04
Number of years dancing professionally ≤3 years 4-8 years 9-15.4 years ≥15.5 years
23(29.5) 20(25.6) 17(21.8) 18(23.1)
12(12.2)28(28.6)32(32.7)26(26.5)
1.00 2.68 3.61 3.04
1.09 – 6.621.45 – 8.991.10 – 6.95
0.03 0.006 0.01
Number of years in present company ≤2 years 3-6 years 7-12 years ≥13 years
22(28.2) 23(29.5) 14(18.0) 19(24.4)
17(17.4)23(23.5)30(30.6)28(28.6)
1.00 1.29 2.77 1.91
0.55 – 3.051.13 – 6.790.81 – 4.51
0.56 0.03 0.03
Company: National Ballet of Canada Royal Swedish Ballet Royal Danish Ballet
23(41.8) 20(37.0) 35(51.5)
32(58.2)34(63.0)33(48.5)
1.00 1.22 0.68
0.57 – 2.640.33 – 1.39
0.61 0.28
48 Table 3.17: Univariate Analysis Results for Self Reported Injury(ballet dancers only) Variable Not injured
n(%) Injured n(%)
OR 95% CI p-value
Country: Canada Sweden Denmark *
23(29.5) 20(25.6) 35(44.9)
32(32.3)34(34.3)33(33.3)
1.00 1.22 0.68
0.57 – 2.640.33 – 1.39
0.61 0.29
Abbreviations: OR, odds ratio; CI, confidence interval, BMI, body mass index. *Israel not included as there were no participating ballet companies in Israel.
49
Table 3.18: Univariate Analysis Results for Self Reported Injury (modern dancers only)
Variable Not injured
n(%) Injured n(%)
OR 95% CI p-value
Sex: Female
22(51.2)
19(48.7)
0.91
0.38 – 2.16
0.83
Age ≤21 years 22-24 years 25-27 years ≥28 years
12(29.3) 6(14.6) 10(24.4) 13(31.7)
7(18.0) 10(25.6)13(33.3)9(23.1)
1.00 2.86 2.23 1.19
0.72 – 11.310.64 – 7.74 0.34 – 4.19
0.13 0.21 0.79
Low body weight (<18.5 BMI)
2(4.9)
1(2.6)
0.51
0.05 – 5.90
0.59
Low income: Below cut-off
9(20.9)
7(18.0)
0.16
0.28 – 2.48
0.73
Number of years dancing total ≤8 years 9-12 years 13-18 years ≥19 years
11(26.2) 10(23.8) 9(21.4) 12(28.6)
9(23.1) 10(25.6)10(25.6)10(25.6)
1.00 1.22 1.36 1.02
0.35 – 4.24 0.39 – 4.79 0.30 – 4.24
0.75 0.63 0.98
Number of years dancing professionally ≤2 years 3-4 years 5-8 years ≥9 years
8(19.1) 10(23.8) 11(26.2) 13(31.0)
10(25.6)4(10.3) 13(33.3)12(30.8)
1.00 0.32 0.95 0.74
0.07 – 1.42 0.28 – 3.23 0.22 – 2.49
0.13 0.93 0.63
Number of years in present company ≤2 years 3-6 years ≥7 years
19(44.2) 12(27.9) 12(27.9)
18(46.2)11(28.2)10(25.6)
1.00 0.97 0.88
0.34 – 2.74 0.31 – 2.54
0.95 0.81
Company: Toronto Dance Theatre Cullberg Ballet Batsheva Dance Company Ensemble Batsheva Kibbutz Dance Company Kibbutz Dance Company 2
7(50.0) 9(56.3) 6(33.3) 6(40.0) 10(90.9) 5(62.5)
7(50.0) 7(43.8) 12(66.7)9(60.0) 1(9.1) 3(37.5)
1.00 0.78 2.00 1.50 0.10 0.60
0.18 – 3.28 0.48 – 8.40 0.34 – 6.54 0.01 – 1.01 0.10 – 3.53
0.73 0.34 0.59 0.05 0.57
50 Table 3.18: Univariate Analysis Results for Self Reported Injury (modern dancers only)
Variable Not injured
n(%) Injured n(%)
OR 95% CI p-value
Country: Canada Sweden Israel *
7(16.3) 9(20.9) 27(62.8)
7(18.0) 7(18.0) 25(64.1)
1.00 0.78 0.93
0.18 – 3.28 0.28 – 3.02
0.73 0.90
Abbreviations: OR, odds ratio; CI, confidence interval, BMI, body mass index. *Denmark not included as there were no participating modern companies in Denmark.
3.9.2 Multivariable analysis (logistic regression)
The model for the multivariable analysis for ballet dancers was created based on the results of
the univariate analysis. Spearman’s correlational coefficient was used to determine correlation
between the continuous variables. Years dancing professionally, years dancing total, years
dancing in present company, and age were all highly correlated with each other (ρ > 0.80). I
have chosen to include only years dancing professionally in the multivariable model. This
variable best represents the professional dancers’ exposure to dance at the elite professional level
and most likely has less variability in the exposure than years dancing total.
The variables included in the multivariable analysis are:
sex, low body weight, years dancing professionally, low income, and rank.
The results of the logistic regression analysis for ballet dancers are reported in Table 3.19. The
variables low body weight, years dancing professionally, and low income were all removed from
the model via backwards stepwise regression. Soloist and principal dancers were more likely to
report an injury than dancers in the corps de ballet (OR = 2.44). Female dancers were less likely
to report an injury than male dancers, but the results are not statistically significant.
51 Table 3.19: Final Model for Logistic Regression Analysis. Factors Associated with Self Reported Injury (ballet dancers only) Variable β OR 95% CI p-value Sex (female) Rank: Corps de ballet Apprentice Soloist/principal Intercept
-0.55
-0.87 0.89 0.23
0.58
1.00 0.42 2.44
0.30 – 1.11
0.10 – 1.69 1.25 – 4.78
0.07
0.22 0.009
Abbreviations: β, beta; OR, odds ratio; CI, confidence interval, BMI, body mass index.
3.10 Factors associated with SEFIP score of ≥3.
3.10.1 Univariate analysis (crude analysis)
The results of the univariate analysis for ballet dancers are reported in Table 3.20. The frequency
of injury for each variable considered for the multivariable analysis is reported with associated
odds ratios and 95% confidence intervals. The variables that have met the criteria to be included
in the regression analysis are low income, rank, number of years dancing total, number of years
dancing professionally, number of years dancing in the present company, and age. The
univariate analyses suggest that ballet dancers earning below the low income threshold are less
likely to report injury than dancers above the threshold. Soloist or principal dancers are more
likely to report a SEFIP score ≥3 than corps de ballet dancers whereas apprentices are less likely
to report a SEFIP score ≥3. Dancers in the three quartiles above 22 years of age were more likely
to report a SEFIP score ≥3 than younger dancers in the reference age group of ≤22 years.
Additionally, dancers dancing 9-15.4 years professionally as well as ≥15.5 years professionally
were more likely to report a SEFIP score ≥3 than the reference group of dancers dancing three or
fewer years professionally. Dancers who reported dancing 17-23 years total and ≥24 years total
were more likely to report a SEFIP score ≥3 than dancers who danced ≤11 years total. Dancers
who had danced 7-12 years or ≥13 years in the present company are more likely to report a
SEFIP score ≥3 than those dancers who had danced ≤2 years in the present company. The
variables sex, low body weight, company, and country were not significantly associated with a
SEFIP score ≥3.
52
The univariate analysis for modern dancers is presented in Table 3.21. The variables that have
met the criteria to be included in the regression analysis are low income, age, and number of
years dancing professionally. The univariate analyses suggest that modern dancers with low
income are more likely to report a SEFIP score ≥3 than dancers above the low income threshold.
Modern dancers between 22-24 years of age are less likely to report a SEFIP score ≥3 than
dancers less than 21 years of age; dancers dancing more than 3-4 years professionally are less
likely to report a SEFIP score ≥3 than dancers dancing two years or less professionally. The
variables sex, low body weight, number of years dancing total, number of years dancing in
present company, and country were not significantly associated with injury. Due to the small
sample sizes of each individual modern dance company, the company variable could not be
analyzed as the validity of the model fit was questionable for this variable.
53 Table 3.20: Univariate Analysis for SEFIP score of ≥3 (ballet dancers only)
Variable SEFIP<3
n(%) SEFIP≥3
n(%) OR 95% CI p-value
Sex: Female
64(59.3)
39(57.4)
0.93
0.50 – 1.71
0.80
Age ≤22 years 23-26 years 27-32 years ≥33 years
34(31.5) 30(27.8) 25(23.2) 19(17.6)
8(11.9) 15(22.4)17(25.4)27(40.3)
1.00 2.13 2.89 6.04
0.79 – 5.71 1.08 – 7.75 2.29 – 15.91
0.14 0.04
0.0003
Low body weight (<18.5 BMI)
34(33.0)
22(32.8)
0.99 0.52 – 1.91 0.98
Low income: Below cut-off
9(8.3)
2(3.0)
0.35
0.07 – 1.66
0.19
Rank: Corps Apprentice Soloist/principal
64(59.3) 10(9.3) 34(31.5)
32(47.1)1(1.5)
35(51.5)
1.00 0.20 2.06
0.03 – 1.63 1.09 – 3.89
0.13 0.03
Number of years dancing total ≤11 years 12-16 years 17-23 years ≥24 years
30(28.0) 35(32.7) 24(22.4) 18(16.8)
8(12.1) 8(12.1) 24(36.4)26(39.4)
1.00 0.86 3.75 5.42
0.29 – 2.56 1.43 – 9.83 2.02 – 14.50
0.78 0.07
0.0008
Number of years dancing professionally ≤3 years 4-8 years 9-15.4 years ≥15.5 years
28(25.9) 36(33.3) 24(22.2) 20(18.5)
7(10.5) 12(17.9)25(37.3)23(34.3)
1.00 1.33 4.17 4.60
0.46 – 3.83 1.53 – 11.321.66 – 12.79
0.59 0.005 0.003
Number of years in present company ≤2 years 3-6 years 7-12 years ≥13 years
32(29.6) 30(27.8) 24(22.2) 22(20.4)
7(10.5) 16(23.9)20(29.9)24(35.8)
1.00 2.44 3.81 4.99
0.88 – 6.75 1.39 – 10.461.83 – 13.58
0.09 0.01 0.002
Company: National Ballet of Canada Royal Swedish Ballet Royal Danish Ballet
35(63.6) 29(52.7) 45(67.2)
20(36.4)26(47.3)22(32.8)
1.00 1.57 0.86
1.00 – 1.00 0.73 – 3.37 0.40 – 1.81
0.25 0.68
54 Table 3.20: Univariate Analysis for SEFIP score of ≥3 (ballet dancers only)
Variable SEFIP<3
n(%) SEFIP≥3
n(%) OR 95% CI p-value
Country: Canada Sweden Denmark *
35(32.1) 29(26.6) 45(41.3)
20(29.4)26(38.2)22(32.4)
1.00 1.57 0.86
0.73 – 3.37 0.40 – 1.81
0.25 0.68
Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain; OR, odds ratio; CI, confidence interval; BMI, body mass index. *Israel not included as there were no participating ballet companies in Israel.
55 Table 3.21: Univariate Analysis for SEFIP score of ≥3(modern dancers only)
Variable SEFIP<3
n(%) SEFIP≥3
n(%) OR 95% CI p-value
Sex: Female
23(51.1)
18(48.7)
0.91
0.38 – 2.16
0.82
Age ≤21 years 22-24 years 25-27 years ≥28 years
8(18.2) 11(25.0) 13(29.6) 12(27.3)
11(30.6)5(13.9) 10(27.8)10(27.8)
1.00 0.33 0.56 0.61
0.08 – 1.34 0.16 – 1.91 0.18 – 2.09
0.12 0.35 0.43
Low body weight (<18.5 BMI)
1(2.3)
2(5.4)
2.40
0.21 – 27.59
0.48
Low income: Below cut-off
6(13.3)
10(27.0)
2.41
0.78 – 7.41
0.13
Number of years dancing total ≤8 years 9-12 years 13-18 years ≥19 years
9(25.0) 13(36.1) 11(30.6) 3(8.3)
11(33.3)7(21.2) 8(24.2) 7(21.2)
1.00 0.44 0.60 1.91
0.12 – 1.57 0.17 – 2.11 0.38 – 9.59
0.21 0.42 0.43
Number of years dancing professionally ≤2 years 3-4 years 5-8 years ≥9 years
8(18.2) 12(27.3) 11(25.0) 13(29.6)
10(27.0)2(5.4)
13(35.1)12(32.4)
1.00 0.13 0.95 0.74
0.02 – 0.77 0.28 – 3.23 0.22 – 2.49
0.03 0.93 0.63
Number of years in present company ≤2 years 3-6 years ≥7 years
22(48.9) 12(26.7) 11(24.4)
15(40.5)11(29.7)11(29.7)
1.00 1.34 1.47
0.47 – 3.84 0.51 – 4.24
0.58 0.48
Country: Canada Sweden Israel *
9(20.0) 11(24.4) 25(55.6)
5(13.5) 5(13.5) 27(51.9)
1.00 0.82 1.94
0.18 – 3.74 0.57 – 6.59
0.80 0.29
Abbreviations: SEFIP, Self Estimated Functional Inability because of Pain; OR, odds ratio; CI, confidence interval, BMI, body mass index. *Denmark not included as there were no participating modern companies in Denmark.
56
3.10.2 Multivariable analysis (logistic regression)
Identical methodology was used as for the previous analysis of self reported injury, but this time
using the outcome variable of SEFIP score of ≥3. The model for the multivariable analysis for
ballet dancers was created based on the results of the univariate analysis. The variables included
in this model are:
Low income, rank, and number of years dancing professionally.
The results of the logistic regression analysis for ballet dancers are reported in Table 3.22. The
variables low income and rank were removed from the model via backwards stepwise regression.
Ballet dancers dancing 9-15.4 years professionally were more likely to have a SEFIP score of ≥3
as ballet dancers dancing ≤3 years professionally (OR = 4.0). This association strengthened with
dancers dancing professionally ≥15.5 years (OR = 4.4).
Table 3.22 Final Model for Logistic Regression Analysis. Factors Associated with SEFIP ≥3
(ballet dancers)
Variable β OR 95% CI p-value Number of years dancing professionally: ≤3 years 4-8 years 9-15.4 years ≥15.5 years Intercept
1.00 0.29 1.39 1.48 -1.39
1.00 1.33 4.00 4.40
0.46 – 3.83 1.47 – 10.91 1.58 – 12.28
0.59 0.007 0.005
Abbreviations: β, beta; SEFIP, Self Estimated Functional Inability because of Pain; OR, odds ratio; CI, confidence interval.
Lastly, a model was created based on the univariate analysis for modern dancers only.
The variables included in this model are:
Low income and number of years dancing professionally.
No variables remained in the model after the logistic regression analysis.
57
3.12 Characteristics of Prevalent Injuries
3.12.1 Body region injured
If dancers had more than one body region injured, they were asked to report the most
problematic body region injured. The same body regions were listed as for the SEFIP. The
results for current most problematic body region injured for dancers are reported stratified by
style and sex in Table 3.23. Results are reported stratified by dance company in Table 3.24.
A similar pattern is noted for all male and female ballet dancers (Table 3.23). The ankles/feet
region has the highest percentage of reported “most problematic injury” followed by knees. This
is followed by either hip or low back regions. Amongst ballet dancers, there was only one
reported upper limb region (shoulders) being a “most problematic injury” and no ballet dancer
reported the neck, elbows, wrists/hands, anterior thighs, shins, or toes as being the “most
problematic injury”.
No similar pattern is noted between the modern dance companies for the “most problematic
injury.”(Table 3.24) In contrast to ballet dancers, neck injuries are reported amongst modern
dancers. The neck is the most frequent body region reported for “most problematic injury” in the
Batsheva Dance Company (45.5%) and Ensemble Batsheva (40.0%). The most frequent region
reported amongst Toronto Dance Theatre dancers is the shoulder region (33.3%). Amongst the
Cullberg Ballet dancers, the knees were the most frequently reported region of injury (37.5%).
No modern dancers reported a problematic injury in the elbows, wrists/hands, anterior thighs, or
shins.
58
Table 3.23: Body Region Injured (current most problematic injury of injured dancers) by
style and sex.
Ballet Modern Body Region Male
n=40 n(%)
Female n=56 n(%)
Male n=19 n(%)
Female n=20 n(%)
Neck
0 0 4(21.1) 6(30.0)
Shoulders
0 1(1.8) 2(10.5) 1(5.0)
Elbows
0 0 0 0
Wrists/hands
0 0 0 0
Upper back
1(2.5) 2(3.6) 1(5.3) 0
Lower back
4(10.0) 6(10.7) 5(26.3) 4(20.0)
Hips
5(12.5) 6(10.7) 3(15.8) 1(5.0)
Ant. Thighs
0 0 0 0
Post. Thighs
1(2.5) 3(5.4) 0 2(10.0)
Knees
7(17.5) 13(23.2) 0 3(15.0)
Shins
0 0 0 0
Calves
0 1(1.8) 1(5.3) 0
Ankles/Feet
22(55.0) 23(41.1) 3(15.8) 1(5.0)
Toes 0 0 0 2(10.0) Only dancers reporting injury were included. All non-dance related injuries have been removed.
59
Table 3.24: Body Region Injured (current most problematic injury of injured
dancers) by company.
Ballet Companies Modern Companies Body Region NBC
N=32 n(%)
RSB N=33 n(%)
RDB N=32 n(%)
TDT N=6 n(%)
CUL N=8 n(%)
BAT N=11 n(%)
ENS N=10 n(%)
Neck
0
0
0
1(16.7)
0
5(45.5)
4(40.0)
Shoulders
0
0
1(3.1)
2(33.3)
0
0
1(10.0)
Elbows
0
0
0
0
0
0
0
Wrists/hands
0
0
0
0
0
0
0
Upper back
1(3.1)
0
2(6.3)
0
1(12.5)
0
0
Lower back
3(9.4)
4(12.1)
4(12.5)
0
2(25.0)
2(18.2)
3(30.0)
Hips
3(9.4)
6(18.2)
2(6.3)
1(16.7)
0
1(9.1)
2(20.0)
Ant. Thighs
0
0
0
0
0
0
0
Post. Thighs
0
3(9.1)
1(3.1)
1(16.7)
1(12.5)
0
0
Knees
6(18.8)
7(21.2)
7(21.9)
0
3(37.5)
0
0
Shins
0
0
0
0
0
0
0
Calves
1(3.1)
0
0
1(16.7)
0
0
0
Ankles/Feet
18(56.3)
12(36.4)
15(46.9)
0
1(12.5)
3(27.3)
0
Toes
0
1(3.0)
0
0
0
0
0
Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance
Company; ENS, Ensemble Batsheva; Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related injuries have been removed.
60
3.12.2 Injury Duration
The majority of male and female ballet and modern dancers are reporting chronic injuries,
particularly of ≥ 6 months duration (Table 3.25). Fifty percent of female ballet dancers, 51.3% of
male ballet dancers and 60.0% of female modern dancers reported current injury of ≥ 6 months
duration. The frequency of ≥ 6 months duration was slightly less in modern male dancers
(36.8%) however they had greater frequencies in the 3months - <6 months duration (21.1%) and
29 days - <3months duration (15.8%).
The Ensemble Batsheva was the only company with a higher frequency of injuries in the 8-28
days duration (40.0%) than the ≥ 6 months duration (30.0%) (Table 3.26). The National Ballet
of Canada had the highest frequency of injury duration less than 29 days (40.5%). By contrast,
the Batsheva Dance Company had no reported injury duration of less than 29 days. The Cullberg
Ballet dancers reported injury durations at two extremes with 75.0% in the ≥ 6 months duration
and 25.0% in the 1-7 days duration.
61
Table 3.25 : Duration of Injury (by style and sex)
Ballet Modern Male
N=39 n(%)
Female N=56 n(%)
Male N=19 n(%)
Female N=20 n(%)
1-7 days
2(5.1)
5(8.9)
2(10.5)
1(5.0)
8-28 days
9(23.1) 9(16.1) 3(15.8)
3(15.0)
29 days - <3months
5(12.8) 5(8.9) 3(15.8) 1(5.0)
3months - <6 months
3(7.7) 9(16.1) 4(21.1) 1(5.0)
≥ 6 months
20(51.3) 28(50.0) 7(36.8) 12(60.0)
Only dancers reporting injury were included. All non-dance related injuries have been removed.
Table 3.26 : Duration of Injury (by company)
NBC N=32 n(%)
RSB N=33 n(%)
RDB N=33 n(%)
TDT N=6 n(%)
CUL N=8 n(%)
BAT N=11 n(%)
ENS N=10 n(%)
1-7 days
3(9.4)
0
4(12.1)
1(16.7)
2(25.0)
0
0
8-28 days
10(31.1) 4(12.1) 4(12.1) 1(16.7) 0 0 4(40.0)
29 days - <3months
1(3.1) 3(9.1) 7(21.2) 1(16.7) 0 2(18.2) 2(20.0)
3months - <6 months
4(12.5) 5(15.2) 3(9.1) 0 0 3(27.3) 1(10.0)
≥ 6 months
14(43.8) 21(63.6) 15(45.5) 3(50.0) 6(75.0) 6(54.5) 3(30.0)
Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva;
Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related
injuries have been removed.
62
3.12.3 Injury Severity
The highest frequency of reported injury severity was moderate for all injured ballet dancers
with 55.3% of injured male ballet dancers and 48.1% of injured female ballet dancers reporting
moderate injury severity (Table 3.27). Injured modern dancers had similar high reported
frequencies of moderate injury severity with 47.4% of injured male modern dancers and 65.0%
of injured female modern dancers reporting moderate injury severity. Severe injury severity was
reported by 21.1% of injured male ballet dancers and 27.8% of injured female ballet dancers.
Similarly, 21.1% of injured male modern dancers and 25.0% of injured female dancers reported
severe injury.
The Royal Danish Ballet and the Cullberg Ballet had the highest frequencies of injured dancers
reporting their injuries as severe (Table 3.28). Forty percent of injured dancers in the Royal
Danish Ballet and 50.0% of injured dancers in the Cullberg ballet reported severe injury.
3.12.4 Time Off Work in Past Year
The majority of injured male and female modern dancers took either no time off from work in
the past year or 1 to 7 days off work due to their injuries (Table 3.29). Amongst injured modern
dancers, 26.3% of males and 45.0% of females took no time off from work; 42.1% of injured
male modern dancers and 30.0% of injured female modern dancers took 1-7 days off from work
due to their injuries.
Injured ballet dancers reported higher frequencies of time off work compared to injured modern
dancers with 10.3% of injured male ballet dancers and 17.9% of injured female ballet dancers
taking between 3 to 6 months off from work compared to 5.3% of injured male modern dancers
and 5.0% of injured female modern dancers taking between 3 to 6 months off from work due to
their injuries (Table 3.29). No injured modern dancers reported taking more than 6 months off
from work due to their injuries. In contrast, 12.8% of injured male ballet dancers and 5.4% of
injured female ballet dancers took more than 6 months off from work due to their injuries.
63
Higher percentages of injured dancers in the Scandinavian ballet companies took longer periods
of time off work than injured dancers in the National Ballet of Canada with 27.3% of injured
Royal Swedish Ballet Dancers and 16.1% of Royal Danish Ballet dancers taking between 3 to 6
months off from work due to their injuries (Table 3.30). Additionally, 3.0% of injured Royal
Swedish Ballet dancers and 16.0% of injured Royal Danish Ballet dancers took more than six
months off work due to their injuries. In contrast, 3.1% of injured National Ballet of Canada
dancers took 3-6 months off and 6.3% of injured National Ballet of Canada dancers took more
than six months off work due to their injuries.
Amongst modern dance companies, no injured dancers took more than 28 days off work with the
exception of the Batsheva Dance Company in which 27.3% of injured dancers took between 29
days to 3 months off from work and 18.2% of injured dancers took between three and six months
off work due to their injuries (Table 3.30). In the Cullberg Ballet, no dancer took more than one
week off from work with 87.5% of injured dancers taking no time off work due to their injuries.
64
Table 3.27 : Injury Severity (by style and sex)
Ballet Modern Male
N=39 n(%)
Female N=54 n(%)
Male N=19 n(%)
Female N=20 n(%)
Minor
9(23.7)
13(24.1)
6(31.6)
2(10.0)
Moderate
21(55.3) 26(48.1) 9(47.4) 13(65.0)
Severe
8(21.1) 15(27.8) 4(21.1) 5(25.0)
Only dancers reporting injury were included. All non-dance related injuries have been removed.
Table 3.28 : Injury Severity (by company)
NBC N=31 n(%)
RSB N=32 n(%)
RDB N=30 n(%)
TDT N=6 n(%)
CUL N=8 n(%)
BAT N=11 n(%)
ENS N=10 n(%)
Minor
9(29.0)
5(15.6)
8(26.7)
1(16.7)
1(12.5)
2(18.2)
4(40.0)
Moderate
17(54.8) 20(62.5) 10(33.3) 5(83.3) 3(37.5) 6(54.5) 5(50.0)
Severe
5(16.1) 7(21.9) 12(40.0) 0 4(50.0) (27.3) 1(10.0)
Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva;
Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related
injuries have been removed.
65
Table 3.30 : Time off work due to current injury in past year (by company)
NBC N=32 n(%)
RSB N=33 n(%)
RDB N=31 n(%)
TDT N=6 n(%)
CUL N=8 n(%)
BAT N=11 n(%)
ENS N=10 n(%)
None
11(34.4) 14(42.4) 4(12.9) 3(50.0) 7(87.5) 1(9.1) 2(20.0)
1-7 days
6(18.8) 5(15.2) 5(16.1) 2(33.3) 1(12.5) 3(27.3) 7(70.0)
8-28 days
8(25.0) 2(6.1) 6(19.4) 1(16.7) 0 2(18.2) 1(10.0)
29 days - <3months
4(12.5) 2(6.1) (19.4) 0 0 3(27.3) 0
≥3months - <6 months
1(3.1) 9(27.3) 5(16.1) 0 0 2(18.2) 0
≥6 months 2(6.3) 1(3.0) 5(16.1) 0 0 0 0 Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related injuries have been removed.
Table 3.29: Time off work due to current injury in past year (by style and sex)
Ballet Modern Male
N=39 n(%)
Female N=56 n(%)
Male N=19 n(%)
Female N=20 n(%)
None
13(33.3) 16(28.6) 5(26.3) 9(45.0)
1-7 days
5(12.8) 11(19.6) 8(42.1) 6(30.0)
8-28 days
9(23.1) 7(12.5) 3(15.8) 2(10.0)
29 days - <3months
3(7.7) 9(16.1) 2(10.5) 2(10.0)
≥3months - <6 months
4(10.3) 10(17.9) 1(5.3) 1(5.0)
≥6 months 5(12.8) 3(5.4) 0 0 Only dancers reporting injury were included. All non-dance related injuries have been removed.
66
3.12.5 Recurrent Injuries
Dancers were asked whether they have had this current injury previously (recurrent injury).
Amongst injured ballet dancers, 48.7% of males and 57.1% of females report recurrent injury
(Table 3.31). Amongst injured modern dancers, 68.4% of males and 44.4% of females report
recurrent injury. Frequency of reported recurrent injury varied between dance companies.
Amongst ballet companies, injured dancers in the Royal Swedish Ballet reported the highest
frequency of recurrent injury (72.7%) compared with 54.8% of injured dancers in the Royal
Danish Ballet reporting recurrent injury and 34.4% of injured dancers in the National Ballet of
Canada reporting recurrent injury (Table 3.32). Reported recurrent injury also varied amongst
modern dance companies with 100.0% of injured dancers of the Toronto Dance Theatre
reporting recurrent injury compared to 66.7% of injured dancers in the Batsheva Dance
Company, 50.0% of dancers in the Ensemble Batsheva and 25.0% of injured dancers in the
Cullberg Ballet reporting recurrent injury.
67
Table 3.31 : Recurrent Injury (by style and sex) Ballet Modern Male
N=39 n(%)
Female N=56 n(%)
Male N=19 n(%)
Female N=18 n(%)
No
20(51.3)
24(42.9)
6(31.6)
10(55.6)
Yes
19(48.7)
32(57.1)
13(68.4)
8(44.4)
Only dancers reporting injury were included. All non-dance related injuries have been removed.
Table 3.32 : Recurrent Injury (by company) NBC
N=32 n(%)
RSB N=33 n(%)
RDB N=31 n(%)
TDT N=6 n(%)
CUL N=8 n(%)
BAT N=9 n(%)
ENS N=10 n(%)
No
21(65.6)
9(27.3)
14(45.2)
0
6(75.0)
3(33.3)
5(50.0)
Yes
11(34.4)
24(72.7)
17(54.8)
6(100.0)
2(25.0)
6(66.7)
5(50.0)
Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva;
Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related
injuries have been removed.
68
3.13 Relationship between SEFIP scores and SRI The frequency of the highest reported SEFIP score reported by injured and non-injured dancers
is reported in Table 3.33. The majority of ballet and modern dancers who have reported being
injured do report SEFIP scores of 3 or 4 denoting some degree of functional impairment.
Between 30.0% to 36.8% of injured ballet and modern dancers reported injury with a highest
SEFIP score of 2 which denotes significant pain but no functional compromise.
The majority of dancers who considered themselves “not injured” had a SEFIP score of 2 or less.
However, 13.7% of “not injured” female ballet dancers had a SEFIP score of 3 compared to
7.7% of “not injured” male ballet dancers. Of the “not injured” modern dancers, 33.3% of males
and 27.3% of females had a SEFIP score of 3. Overall, 19.8% of all “not injured” dancers had a
SEFIP score of 3.
Table 3.33: Highest Reported SEFIP Score for Injured and Non-injured Dancers
Ballet Modern Injured Not Injured Injured Not Injured SEFIP score
Male N=47 n(%)
Female N=52 n(%)
Male N=26 n(%)
Female N=26 n(%)
Male N=20 n(%)
Female N=19 n(%)
Male N=21 n(%)
Female N=22 n(%)
0 0 0 2(7.7) 0 0 0 0 0 1 4(8.5) 5(9.6) 8(30.8) 19(37.3) 2(10.0) 0 7(33.3) 9(40.9) 2 16(34.0) 16(30.8) 14(53.8) 2(49.0) 6(30.0) 7(36.8) 7(33.3) 7(31.8) 3 18(38.3) 28(53.8) 2(7.7) 7(13.7) 12(60.0) 10(52.6) 7(33.3) 6(27.3) 4 9(19.1) 3(5.8) 0 0 0 2(10.5) 0 0 0 = “very well”; 1 = “some pain but not much problem”; 2 = “pretty much pain but I can handle it”; 3 = “much pain, must avoid some movements”; 4 = “cannot work in the production because of pain”. Abbreviations: SEFIP, Self-Estimated Functional Inability because of Pain
3.14 Reporting of Dance-related Injuries Frequency of dancers who have not reported their injury is detailed in Table 3.34. The aggregate
percentage of ballet dancers who have not reported an injury is 15.5%. Amongst the modern
dance companies, the Toronto Dance Theatre has a much higher percentage of dancers not
reporting an injury (66.7%) as compared to the other modern dance companies.
69
Reasons why a dancer has not reported an injury are reported in Table 3.35. All the options given
were chosen as reasons for not reporting an injury (Appendix 2, Section D). The four most cited
reasons overall for both ballet and modern dancers were: “It did not affect my work”, “Pain is an
inherent part of dancing”, “I can cope with the pain”, and “I did not want to stop dancing”.
For those dancers who have reported an injury, the results of to whom dancers are reporting their
injury are listed in Table 3.36. Twelve dancers reported to “other” which included: assistant to
the artistic director, ballet secretary, choreographer, insurance company, government, stage
manager, and teacher.
Table 3.37 reports the frequency of all injuries reported to the local workers’ compensation
board or national insurance as a work injury by company. Injuries were reported as work injuries
only in the Scandinavian ballet companies and the Batsheva Dance Company in Israel.
Table 3.34: Frequency of non-reported injuries
Injuries not reported by dancers n(%)
Ballet dancers (N=97)
15(15.5)
National Ballet of Canada (N=32)
4(12.5)
Royal Swedish Ballet (N=33)
6(18.2)
Royal Danish Ballet (N=32) 5(15.6) Modern dancers (n=39)
7(17.9)
Toronto Dance Theatre (N=6)
4(66.7)
Cullberg Ballet (N=8)
1(12.5)
Batsheva Dance Company (N=11)
1(9.1)
Ensemble Batsheva (N=10)
1(10.0)
Only injured dancers. Non-dance related injuries removed.
70
Table 3.35: Reasons for not reporting an injury.
Reason for not reporting an injury: Ballet
N=15 n(%)
Modern N=7 n(%)
I did not feel it was important.
3(20.0) 2(28.6)
It did not affect my work.
6(40.0) 5(71.4)
I did not want to be seen as unreliable.
3(20.0) 2(28.6)
Pain is an inherent part of dancing.
5(33.3) 5(71.4)
I did not want to negatively affect the production.
3(20.0) 1(14.3)
I can cope with the pain.
8(53.3) 7(100.0)
I did not want to stop dancing.
4(26.7) 5(71.4)
I did not want to lose a role.
2(13.3) 2(28.6)
I did not want to let my company down.
2(13.3) 2(28.6)
Other 1(7.1) 0 Only injured dancers who stated they did not report their injury are
included. Non-dance related injuries removed.
71
Table 3.36: To whom are dancers reporting their injuries? Ballet dancers
Modern dancers
NBC (N=28) n(%)
RSB (N=27) n(%)
RDB (N=27) n(%)
TDT (N=2) n(%)
CUL (N=7) n(%)
BAT (N=10) n(%)
ENS (N=9) n(%)
Rehearsal Director
22(78.6) 11(40.7) 19(70.4) 1(50.0) 5(71.4) 10(100.0) 9(100.0)
Company Manager
7(25.0) 2(7.4) 10(38.5) 1(50.0) 2(28.6) 6(60.0) 1(11.1)
Artistic Director
16(57.1) 13(48.1) 17(65.4) 1(50.0) 5(71.4) 7(70.0) 3(33.3)
Company Health Professional
24(85.7) 26(96.3) 24(88.9) 0 2(28.6) 10(100.0) 5(55.6)
Health Professional not related to company
16(57.1) 11(40.7) 5(20.0) 2(100.0) 4(57.1) 3(30.0) 2(22.2)
Other
5(18.5) 5(18.5) 1(4.0) 1(50.0) 0 0 0
Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva.
Kibbutz Dance Company and Kibbutz Dance Company 2 results not detailed due to low response rates.
72
Table 3.37: Injuries Reported as Work Injuries
Injuries reported as work injuries n(%)
Ballet
National Ballet of Canada (N=32)
n/a
Royal Swedish Ballet (N=33)
10(30.3)
Royal Danish Ballet (n=32)
16(50.0)
Modern
Toronto Dance Theatre (N=6)
0
Cullberg Ballet (N=8)
0
Batsheva Dance Company (N=10)
3(30.0)
Ensemble Batsheva (N=10)
0
Kibbutz Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 results are not reported due to small sample sizes. Only dancers reporting injury were included. All non-dance related
injuries have been removed.
73
3.15 Dancers’ Attitudes and Perceptions of Injury
Tables 3.38 reports dancers’ responses to agree/disagree scales of various attitudinal questions
regarding injury and dance-related pain stratified by style and self-reported injury status. The
results are summarized in aggregate format for all dancers as follows:
1. The majority of dancers (80.6%) disagree with the statement: “I consider myself injured if I
have any pain when I dance.”
2. The majority of dancers agree (70.4%) with the statement “I consider myself injured if I must
modify movements when I dance due to pain”. However, a significant number of dancers
disagree (29.6%) with this statement, especially those who are not injured.
3. The majority of dancers agree (72.8%) with the statement “I consider myself injured if I miss
a company class or rehearsal due to dance-related pain.” However, a significant number of
dancers disagree (27.1%) with this statement.
4. The majority of dancers agree (70.8%) with the statement “I consider myself injured if I must
take medication due to my dance-related pain.” However, a significant number of dancers
disagree (29.2%) with this statement, especially ballet dancers.
5. The majority of dancers agree (56.9%) with the statement, “I consider myself injured if I must
seek care from a health-care practitioner for my dance-related pain.” However, a significant
number of dancers do disagree (43.1%) with this statement.
6. The majority of dancers agree with the following statements:
a. “I consider myself injured if I miss more than one day of work due to dance-related
pain.” (Agree: 81.3%; Disagree: 11.7%). Ballet dancers were more likely to disagree
with this statement than modern dancers.
74
b. “I consider myself injured if I have visual signs such as redness or swelling that
accompany my pain.” (Agree: 85.1%; Disagree: 14.9%). Modern dancers were more
likely to disagree with this statement than ballet dancers.
7. Dancers overwhelmingly agree about the following two statements:
a. “I consider myself injured if I a m unable to participate in a performance due to
dance- related pain.” (Agree: 96.8%; Disagree: 3.2%)
b. “I consider myself injured if I must go to the hospital due to my dance-related pain.”
( Agree: 97.3%; Disagree: 2.7%)
Table 3.38: Responses to Attitudinal Questions I consider myself injured if I…. Style Injury
Status Strongly
Agree n(%)
Agree
n(%)
Mildly agree n(%)
Mildly disagree
n(%)
Disagree
n(%)
Strongly disagree
n(%) Injured (N=99)
3(3.0) 5(5.1) 17(17.2) 9(9.1) 43(43.4) 22(22.2) Ballet
Not injured (N=85)
0 1(1.3) 8(10.4) 10(13.0) 33(42.9) 25(32.5)
Injured (N=39)
0 3(7.7) 7(17.9) 8(20.5) 14(35.9) 7(17.9)
… have any pain when I dance.
Modern
Not injured (N=43)
0 2(4.7) 4(9.3) 5(11.6) 25(58.1) 7(16.3)
Injured (N=98)
13(13.3) 30(30.6) 36(36.7) 6(6.1) 12(12.2) 1(1.0) Ballet
Not injured (N=77)
3(3.8) 27(34.6) 17(21.8) 16(20.5) 12(15.4) 2(2.6)
Injured (N=39)
4(10.3) 11(28.2) 15(38.5) 8(20.5) 0 1(2.6)
… must modify movements when I dance due to pain.
Modern
Not injured (N=43)
3(7.0) 12(27.9) 10(23.3) 9(20.9) 9(20.9) 0
75
Table 3.38: Responses to Attitudinal Questions I consider myself injured if I…. Style Injury
Status Strongly
Agree n(%)
Agree
n(%)
Mildly agree n(%)
Mildly disagree
n(%)
Disagree
n(%)
Strongly disagree
n(%) Injured (N=99)
17(17.2) 28(28.3) 22(22.2) 10(10.1) 20(20.2) 2(2.0) Ballet
Not injured (N=77)
12(15.6) 26(33.8) 15(19.5) 10(13.0) 10(13.0) 4(5.2)
Injured (N=39)
6(15.4) 20(51.3) 10(25.6) 0 3(7.7) 0
…miss a company class or rehearsal due to dance-related pain.
Modern
Not injured (N=43)
6(14.0) 20(46.5) 6(14.0) 3(7.0) 5(11.6) 3(7.0)
Injured (N=99)
18(18.2) 40(40.4) 18(18.2) 10(10.1) 12(12.1) 1(1.0) Ballet
Not injured (N=77)
11(14.3) 36(46.8) 12(15.6) 7(9.1) 10(13.0) 1(1.3)
Injured (N=39)
13(33.3) 18(46.2) 6(15.4) 1(2.6) 1(2.6) 0
…miss more than one day of work due to dance-related pain.
Modern
Not injured (N=43)
11(25.6) 25(58.1) 2(4.7) 2(4.7) 3(7.0) 0
76
Table 3.38: Responses to Attitudinal Questions I consider myself injured if I…. Style Injury
Status Strongly
Agree n(%)
Agree
n(%)
Mildly agree n(%)
Mildly disagree
n(%)
Disagree
n(%)
Strongly disagree
n(%) Injured (N=99)
49(49.5) 42(42.4) 6(6.1) 1(1.0) 1(1.0) 0 Ballet
Not injured (N=77)
35(45.5) 33(42.9) 4(5.2) 2(2.6) 2(2.6) 1(1.3)
Injured (N=39)
25(64.1) 12(30.8) 2(5.1) 0 0 0
… am unable to participate in a performance due to dance-related pain.
Modern
Not injured (N=43)
26(60.5) 14(32.6) 2(4.7) 0 1(2.3) 0
Injured (N=98)
19(19.4) 24(24.5) 23(23.5) 14(14.3) 18(18.4) 0 Ballet
Not injured (N=77)
11(14.3) 19(24.7) 19(24.7) 12(15.6) 13(16.9) 3(3.9)
Injured (N=39)
13(33.3) 12(30.8) 8(20.5) 4(10.3) 2(5.1) 0
…must take medication due to my dance-related pain.
Modern
Not injured (N=43)
14(32.6) 7(16.3) 13(30.2) 3(7.0) 6(14.0) 0
77
Table 3.38: Responses to Attitudinal Questions I consider myself injured if I…. Style Injury
Status Strongly
Agree n(%)
Agree
n(%)
Mildly agree n(%)
Mildly disagree
n(%)
Disagree
n(%)
Strongly disagree
n(%) Injured (N=99)
16(16.2) 17(17.2) 19(19.2) 16(16.2) 27(27.3) 4(4.0) Ballet
Not injured (N=77)
10(13.0) 22(28.6) 10(13.0) 17(22.1) 14(18.2) 4(5.2)
Injured (N=39)
3(7.7) 15(38.5) 12(30.8) 6(15.4) 3(7.7) 0
…must seek care from a health-care practitioner for my dance-related pain.
Modern
Not injured (N=43)
2(4.7) 9(20.9) 12(27.9) 6(14.0) 11(25.6) 3(7.0)
Injured (N=99)
61(61.6) 29(29.3) 6(6.1) 3(3.0) 0 0 Ballet
Not injured (N=77)
42(54.5) 24(31.2) 8(10.4) 2(2.6) 1(1.3) 0
Injured (N=39)
24(61.5) 13(33.3) 2(5.1) 0 0 0
… must go to the hospital due to my dance-related pain.
Modern
Not injured (N=43)
23(53.5) 17(39.5) 2(4.7) 0 0 1(2.3)
78
79
Table 3.38: Responses to Attitudinal Questions I consider myself injured if I…. Style Injury
Status Strongly
Agree n(%)
Agree
n(%)
Mildly agree n(%)
Mildly disagree
n(%)
Disagree
n(%)
Strongly disagree
n(%) Injured (N=98)
26(26.5) 37(37.8) 21(21.4) 8(8.2) 6(6.1) 0 Ballet
Not injured (N=75)
19(25.3) 32(42.7) 17(22.7) 3(4.0) 3(4.0) 1(1.3)
Injured (N=39)
13(33.3) 13(33.3) 7(17.9) 2(5.1) 2(5.1) 2(5.1)
… have visual signs such as redness or swelling that accompany my pain.
Modern
Not injured (N=43)
8(18.6) 13(30.2) 11(25.6) 7(16.3) 3(7.0) 1(2.3)
80
3.16 Company Contextual Information
Company contextual information for the 2007-2008 season is detailed in Table 3.39 for easy
comparison. The participating ballet companies range in size from 67 to 83 dancers, whereas the
modern dance companies are smaller ranging in size from 12 to 20 dancers. However, the
number of performance and productions per season are not dependent on the size of the
company. The Royal Danish Ballet had the highest number of performances overall with 153
total performances and 12 separate productions for the 2008 season. The Ensemble Batsheva had
the second highest number with 120 performances for the season and eight productions. The
Toronto Dance Theatre had the lowest number of performances with 30 for the season and four
productions.
Daily company class is required in all companies with the exception of the Royal Danish Ballet
and the National Ballet of Canada; however, dancers are still expected to attend the class. Onsite
healthcare treatment is available at the workplace for all the ballet companies as well as the
Kibbutz Contemporary Dance Companies. The Royal Danish Ballet was the only company to
have “sick classes” specifically for injured dancers.
The number of weeks of vacation also varied greatly ranging from a low of three weeks for the
National Ballet of Canada dancers to a high of 12 weeks for the Royal Danish Ballet and Toronto
Dance Theatre dancers. The ballet dance company dancers all belong to unions as well as the
Cullberg Ballet dancers. No other modern dance companies were unionized. The Royal Swedish
Ballet is the only company to perform on a raked (sloped) stage in their home theatre. Studios for
training and rehearsals are also raked at the Royal Swedish Ballet.
Table 3.39 : Company Contextual Data for the 2007-08 Season Dance Company
Size of Company
(# of dancers)
Performances/ year
Productions/ year
Daily Company
Class
Onsite treatment available?
Weeks vacation/year.
Dancers Unionized?
“Sick Classes”
for injured dancers
Raked Stage?
Ballet:
NBC
69 85 4 Optional Yes 3 Yes No No
RSB
67 73 8 Required Yes 10 Yes No Yes
RDB
83 153 12 Optional Yes 12 Yes Yes No
Modern:
TDT
16 30 4 Required No 12 No No No
CUL
20 55 8 Required No 6 Yes No No
BAT
20 110 8 Required No 6 No No No
ENS
15 120 8 Required No 6 No No No
KDC
17 70 6 Required Yes 4 No No No
KDC2 12 100 4 Required Yes 4 No No No Abbreviations: NBC, National Ballet of Canada; RSB, Royal Swedish Ballet; RDB, Royal Danish Ballet; TDT, Toronto Dance Theatre; CUL, Cullberg
Ballet; BAT, Batsheva Dance Company; ENS, Ensemble Batsheva; KDC, Kibbutz Contemporary Dance Company; KDC2, Kibbutz Contemporary Dance Company 2
81
82
Chapter 4: Discussion
4.1 Principal Findings
Prevalence of Injury
Almost all of the dancers in this study reported some degree of current dance-related pain. This
finding is consistent with the findings reported previously in the literature.4, 13 This is one of the
largest cross-sectional studies of musculoskeletal injury in professional ballet and modern
dancers. I have focused specifically on point prevalence in order to reduce recall bias. A study of
Australian athletes found that only 61% were able to remember the number, body region and
diagnoses of injuries sustained in the previous 12 months. 53
The point prevalence of dance-related musculoskeletal injury in dancers is high using two
distinct outcomes for injury, and the estimate varies by case definition. The point prevalence of
self-reported injury was higher than the point prevalence of SEFIP ≥3 injury in all companies
with the exception of the Kibbutz Contemporary Dance Company and the Kibbutz
Contemporary Dance Company 2. The prevalence estimates for these two companies must be
interpreted with caution as these were the two companies that had the lowest response rates. It is
possible that due to the difficult circumstances on the day of the survey, injured dancers left to
deal with their injuries and did not participate. Self reported injury and SEFIP injury estimates
may have been higher if that was indeed the case in this group. I have calculated the prevalence
rates of self-reported injury with the assumption that all non-participants in the Kibbutz
Contemporary Dance Company and Kibbutz Contemporary Dance Company 2 would have
considered themselves injured. Under this assumption, the prevalence (with 95% CI) of self-
reported injury would increase from 9.1% to 41.1% (17.8 - 64.6) and from 37.5% to 58.3% (30.4
– 86.2) respectively. If these non-participants were to have reported SEFIP scores ≥3 as well,
the Kibbutz Contemporary Dance Company prevalence of SEFIP ≥3 injury would increase from
54.5% to 70.6% (48.9 – 92.3) and the Kibbutz Contemporary Dance Company prevalence would
remain at 100.0%. However, cultural attitudes towards pain and injury may also account for this
difference given that the Kibbutz Contemporary Dance Companies had the highest overall
percentage of dancers native to that country (Table 3.4). Cultural and racial differences in
perception of pain and injury have been reported in various cultures.54
82
83 Injury Patterns
Injury patterns differ between professional ballet and modern dancers. The injury patterns for
self-reported injury in professional ballet dancers are consistent with previous findings in the
literature.4 However, professional modern dancers do not have a distinct pattern with and the
frequency of injury for specific body regions differs between modern companies. Although there
are variations between specific schools of ballet, for the most part, ballet is a fairly uniform
language of movement. Modern dance however originated as a rebellion against ballet and there
are many different types of techniques or schools that vary widely from one another. This
variation in repertoire and style of modern dance between the companies participating in this
study likely explains the variation in the types of injuries that dancers in a particular modern
dance company experienced. It is interesting to note that at the time the survey was performed,
the Royal Danish Ballet was performing a mixed repertoire evening that included a modern
dance piece by the choreographer of the Batsheva Dance Company, yet their injury patterns did
not deviate significantly from those of other ballet companies.
Factors Associated with Injury
This is the largest cross-sectional study of professional ballet and modern dancers to make use of
a multivariable analysis to investigate factors independently associated with dance-related injury.
It is important to note that these factors did vary with the two different case definitions used.
Rank was independently associated with self reported injury in ballet dancers with soloists and
principal dancers more likely to report injury than corps de ballet dancers. Ramel et al had a
similar finding in professional Swedish ballet dancers.14 This may be explained by the more
challenging roles that soloists and principal dancers perform. Additionally, the pressure to
continue to dance even when injured may be greater for soloists and principal dancers if there is
no understudy.
There was a trend for female ballet dancers to be less likely to be injured for the self-reported
injury outcome, although the results were not statistically significant. This may be explained by
the higher percentage of female ballet dancers with a SEFIP score of ≥3 that did not consider
themselves injured (Table 3.41). Hamilton et al. found differences in personality traits between
male and female ballet dancers.18 They report that male ballet dancers have more negative
personality traits and psychological distress than female dancers or men in the general
population. Female ballet dancers were reported to have been more adjusted than male ballet
84 dancers, as well as tough-minded, disciplined, and caring than the male ballet dancers.18 It is
possible that these traits may play a role in their perception of injury. It is also possible that
physiological differences in female body types may make them less susceptible to injury than
male ballet dancers. For example, greater flexibility or bone and joint structure in females may
make them more able to attain the typical ideal aesthetic requirements in ballet such as turn out
at the hips. However, these physiological differences have not yet been shown to be associated
with injury in dancers.
Number of years dancing professionally was independently associated with injury in ballet
dancers for the SEFIP ≥3 outcome. The longer one is exposed to dancing at an elite professional
level, the more likely one is to have functional difficulties due to the rigorous physical strain
dancers put their bodies through.
For modern dancers, the only factor that was found to be associated with self-reported injury was
company. The Kibbutz Contemporary Dance Company was less likely to report injury than
dancers in the Toronto Dance Theatre. The reason for this association can be seen clearly from
the prevalence estimates with the Kibbutz Contemporary Dancers reporting very low frequencies
of self-reported injury as mentioned previously. This association was not found with the
SEFIP≥3 outcome.
Injury Characteristics and Time-loss from Work
The majority of injured ballet and modern dancers reported injuries of longer than three months
duration. This suggests that the majority of injuries in both ballet and modern dancers are of a
chronic nature. Additionally, between 21-28% of all injured dancers consider their injury severe
in nature. However, there is a disconnect in certain instances between the injury severity rating
and the amount of time that dancers are taking off work due to their injury. Very few modern
dancers are taking any extended time off work due to their injuries. In fact, in the Cullberg
Ballet, although 50% of injured dancers rated their injuries as severe, only one dancer took a
week off of work while the remaining 87.5% of injured dancers reported taking no time off work
due to their injury in the preceding year.
Scandinavian ballet dancers and dancers in the Batsheva Dance Company were more likely to
take extended amounts of time off work due to their injuries. Societal support may help to
85 explain this ability to take time off work when injured. Scandinavian dancers have better overall
job security and social support than dancers in Canada and Israel.3 Israel likely lies somewhere
between Scandinavia and Canada regarding both social support for injured dancers as well as job
security for injured dancers. However, this does not explain the reason why Cullberg Ballet
dancers are not taking very much time off from work, as it is a Swedish dance company with the
same social and health benefits for injured dancers as the Royal Swedish Ballet. A likely reason
for this difference may lie in the make-up of the company members. The Cullberg Ballet had the
lowest percentage of dancers from the country of the dance company with only 31.3% of their
dancers of Swedish origin. Foreign dancers may either not understand the benefits they have,
may have different cultural attitudes towards these social benefits, or may not yet have access to
the full job security benefits if they have not been in the company for a minimum of three years.
In this case, the median number of years in the present company for Cullberg Ballet dancers was
2.5 years compared to 7.5 years for dancers in the Royal Swedish Ballet.
The size of the company may also influence the ability of a dancer to take any extended time off
work when injured. Although the Royal Danish Ballet has the highest number of performances
per year (153), it also has the largest number of dancers (83). Therefore, they have the ability to
substitute dancers in roles in each work. The Ensemble Batsheva performs 120 performances per
year, yet has a much smaller number of dancers (15). This may significantly increase the number
of performances per year that each individual dancer performs as well as the amount of rehearsal
hours for each dancer. However, this may also increase the amount of pressure on the individual
injured dancer to return to work quickly.
Healthcare and Pain Medication Use
The majority of professional dancers overall are receiving treatment for their dance related pain
and primarily from physiotherapists and massage therapists. Very few ballet dancers were
receiving care from medical doctors and no modern dancers reported receiving care from
medical doctors. The difference in health care use between these groups may be due to the
availability of medical doctor (MD) care. All of the ballet companies had an MD on-site at least
once a week whereas no modern dance company provided access to onsite medical doctor care.
The lower use of medical doctor care compared to other types of healthcare may be also due in
part to the nature of the injures if they are primarily chronic overuse type of injuries. Therefore, a
medical doctor may refer the dancer for physiotherapy or rehabilitation and only continue to
86 follow those injuries which are acute in nature or may require surgery. Dancers may also have
been referred for physiotherapy for previous injuries and due to the ease of access to
physiotherapy care, choose to first attempt care with a physiotherapist.
A large percentage of dancers are using pain medication for their dance-related pain. This figure
was especially high in Canadian dancers with over 50% using pain medication for dance-related
pain at the time of data collection. The reason for higher use of pain medications in Canadians is
unclear however this may possibly be due to cultural differences.
Injury Reporting
More than 15% of injured ballet and modern dancers did not report their injuries. Two of the four
most cited reasons for not reporting an injury (“Pain is an inherent part of dancing” and “I can
cope with the pain”) may indicate that dancers believe pain is part and parcel of their working
lives. The reason “I did not want to stop dancing” may be a red flag, however, for the pressure
that dancers feel to continue to dance despite being in significant pain and considering
themselves injured. Additional reported reasons that may point to a psychosocial component for
not reporting injury include: “I did not want to be seen as unreliable”, “I did not want to
negatively affect the production”, “I did not want to lose a role”, and “I did not want to let my
company down”. Of those dancers who did report their injuries, most did so to either the
rehearsal directors or company health professionals (in those companies that had a company
health professional).
Of additional interest is the fact that 50% of injured Danish dancers had reported their injuries to
the local worker’s compensation board followed by 30% in the Royal Swedish Ballet and the
Batsheva Dance Company. No Canadian dancers had injuries reported to the worker’s
compensation board. The National Ballet of Canada dancers are not eligible for workers’
compensation because they are primarily contract workers. However, no dancers from the
Toronto Dance Theatre had reported an injury that was reported to the workers’ compensation
board as well.
Attitudes Towards Injury
This is also one of the first studies to explore professional dancers’ attitudes towards injury. Pain
alone is not an indicator of injury for professional dancers. For the most part, dancers agreed they
87 would consider themselves injured if they could not perform or had to go to hospital due to
dance-related pain with only a few dancers disagreeing with these statements. The majority of
dancers also agreed they would consider themselves injured if they had visual signs such as
redness and swelling accompanying their pain, had to seek healthcare, or had to take medications
due to their pain. However, many dancers disagreed with these statements. Additionally,
attitudes regarding time-loss from work and functional changes besides not being able to perform
were varied. Most dancers agreed they would consider themselves injured if they missed more
than one day of work, missed company class or rehearsal, or had to modify their movements due
to pain, but many dancers also disagreed with these statements.
88
4.2 Implications of Principal Findings
The difference in prevalence estimates for two different injury outcomes points to the importance
of case definition in dance injury and surveillance research. Future prospective as well as cross-
sectional studies should use clear definitions of injury. Due to the variations in attitudes and
perceptions towards injury seen in this population of dancers, I suggest incorporating a broad
definition of injury in order to capture as many injured dancers as possible. These injuries can
then be subdivided as Bronner et al. have suggested if the dancer has lost time from work, sought
healthcare for their injury, has financial loss from their injury, or has only a physical complaint.36
Functional impairment alone may be problematic as a definition to capture and study injured
dancers as many dancers are continuing to dance with pain and may potentially be injured. As a
significant number of dancers do not consider themselves injured even when modifying
movement due to pain, they may resist reporting themselves as injured. Additionally, time-loss
from work alone should not be used as a definition to capture and study injured dancers as the
results suggest that some injured dancers may not be losing any time from work.
The prevalence of dance-related pain and injury is very high regardless of the definition and the
long-term consequences of this are unknown. Additionally, injured dancers are reporting very
long injury durations, many beyond six months, suggesting chronic injury. Therefore, there is an
urgent need to investigate interventions to help control injury and understand the long-term
implications of these conditions. There is preliminary evidence that comprehensive injury
management and prevention programs for both professional ballet and modern dancers may
decrease injury incidence as well as economic costs associated with injury.25, 27, 28 However these
studies are uncontrolled observational designs and therefore the conclusions are limited.
Since injury patterns vary between professional modern dance companies, a tool such as the
SEFIP may be useful for seasonal planning. Modern dance companies will often have visiting
choreographers as well as repertoire that varies from season to season. Using a tool such as the
SEFIP can help to identify which body areas are more likely to be injured during a certain
production. If that production is repeated later in the season or in a subsequent season, these
injury types can then be anticipated. This could be useful in planning repertoire or identifying
and modifying choreography to help minimize injury. Ramel suggested that dancers with a
SEFIP score of 2 or more be examined by a dance science professional.40 The SEFIP could be
89 useful for the dance company health professionals to assist in identifying dancers that continue to
work with functional issues (SEFIP score ≥3) yet are reluctant to consider themselves injured as
may have been the case in this study with the dancers in the Kibbutz Contemporary Dance
Companies. These dancers might be targeted for increased confidential surveillance and
treatment of their injuries.
This study suggests that rank is independently associated with injury in ballet dancers. Dance
health professionals should aim to identify the special needs of these dancers in their injury
prevention and rehabilitation programs. The number of years dancing professionally was also
found to be independently associated with a SEFIP score ≥3 in ballet dancers. Efforts should be
made to support older and more experienced dancers deal with their injuries. As injury may
possibly lead to the end of a career for a dancer, this support should include physical as well as
psychological components. These findings need to be confirmed in a prospective study design to
determine if the associated factors are indeed risk factors for injury.
It is clear that the high prevalence of reported injury, lengthy reported injury durations, and in
some cases extended time off work due to these injuries, places a high burden on the dance
companies themselves to deal with their injured workers. The discrepancy however between the
higher percentages of ballet dancers taking extended time off from work due to their injuries
compared to modern dancers is concerning. This discrepancy is also seen between the amount of
time that ballet dancers in the Scandinavian countries were off work due to their injuries
compared to ballet dancers in Canada. This suggests that company or country level factors may
play a role in the ability of a dancer to take the appropriate time off to recover from an injury.
This may in turn have an effect on future injury or potentially a shortened career. The difference
in access to benefits and frequency of reporting of injuries as work injuries between the countries
supports this need for further exploration of these societal and company level factors. Although
the social benefits in Scandinavian countries are vastly different than in Canada or Israel, all
dance companies should strive to provide their dancers with job security and the ability to take
the appropriate time off work to recover from injuries as recommended by healthcare
professionals. This responsibility does not lie however with the dance company alone.
Government support for dance and the arts in general is higher in Scandinavian countries than in
Israel or Canada. Governments should be aware of the high burden of pain and injury in
professional dancers and strive to increase the needed support to these populations.
90
Larger studies are needed to investigate these higher level company and country factors with
multi-level modeling. This will help to determine if factors such as number of performances,
productions, availability of social or medical support or other company or country level factors
are associated with injury. In the meantime however, smaller companies with high numbers of
performances and productions should be aware that their dancers may have an increased dance
exposure compared to dancers in larger companies or companies with smaller number of
performances or productions. Efforts to decrease this exposure and potentially decrease injury in
these dancers should include increasing the number of dancers in the company and/or decreasing
the number of performances per season. Exposure to dance is more easily measured in a
prospective study, and a better measure of exposure involves time at risk. Ideally, time-based
exposure should be evaluated by determining number of injuries per 1000 hours of dance-
participation as has been adopted by many European sports injury researchers.36
Two subsets of dancers have been identified that are of special concern. These are dancers who
are not reporting their injuries and dancers who are dancing through pain and functional issues
potentially as a result of their attitudes towards injury. The fact that more than 15% of all injured
professional dancers have not reported their injuries is very important as this affects all measures
of injury prevalence and incidence. Future studies of musculoskeletal injury in dancers should
keep this in mind when deciding how best to capture injured dancers. Dance injury registries
should make efforts to use those individuals that dancers are most likely to report their injuries
to, such as rehearsal directors and company health professionals. Rehearsal directors often have
the most work contact with dancers and therefore a high level of trust may be developed.
Dancers may also be very trusting of company health professionals due to the guarantee of
confidentiality. Of the reasons given for not reporting an injury, “I did not want to stop dancing”
especially deserves further attention. This may point towards a fear of dealing with or accepting
the possibility of injury and possibly losing time from work. This may cause a dancer to continue
to dance with pain and possibly ignore warning signs of injury. Additional reasons reported point
towards psychosocial pressures within the company. It is clear that there is a need for
professional dance companies to develop measures that allow dancers, who are in pain and may
be injured, to feel comfortable and secure enough to report their injuries.
91 The attitudinal results suggest that there is a subset of dancers who have attitudes towards injury
that may cause them to continue to dance with pain and functional impairment. It is possible that
the experience of injury may lead a dancer to better understand injury and this may have an
impact on their perception of considering themselves injured or not injured. Although many
dancers who are modifying movement due to pain may consider themselves injured, the
preliminary findings of dancers’ attitudes towards injury, as well as the fact that 19.8% of
dancers who did not consider themselves injured had a SEFIP score of 3, bring light to the fact
that many dancers are dancing with pain as well as functional impairment without considering
themselves injured. There is some suggestion in the literature that these behaviors may lead to
chronic injury, although this has yet to be proven.14, 20 However, the high prevalence of reported
chronic injury in this group of professional dancers lends support to this theory. Education
regarding pain and injury is essential for these two subsets of dancers so they may be better able
to recognize when they are injured and seek the appropriate care. Qualitative research is needed
to better understand dancers’ attitudes and perceptions of pain and injury.
There is also some suggestion from the findings of this study that dancers may be using pain
medications (prescription and non-prescription) in order to continue to dance with pain which
may also have an impact on one’s attitudes towards pain and injury. This is especially worrisome
given the low prevalence of dancers under medical care for their dance-related pain. Studies of
elite Olympic athletes have demonstrated a dangerous overuse of non-steroidal anti-
inflammatory drugs (NSAIDs) as well as inappropriate use of concurrent multiple types of
NSAIDs and other medications.55 Gastrointestinal and central nervous system adverse effects
associated with NSAID use have been commonly reported in elite athletes.56 Additionally, there
is evidence from animal studies that the long term use of NSAIDs may actually inhibit protein
synthesis and therefore delay tissue healing.56 Further studies of pain medication use in
professional dancers are warranted, especially in Canada. Educational measures are urgently
needed for dancers regarding the appropriate use of pain medications and potential adverse
reactions.
4.3 Strengths and Limitations
This is the largest cross-sectional study of solely professional ballet and modern dancers to date
and one of the first international studies of professional dancers. I have focused on the point
92 prevalence of injury in these dancers in order to reduce recall bias. Additionally, I used
multivariable analysis to measure associated factors which has rarely been used in studies of
professional dancers. The response rate in this study was very good overall and I used a
comprehensive and psychometrically sound inventory of questions.
Care should be taken in interpreting factors associated with injury. As this is a cross-sectional
study, these should not be interpreted as risk factors. Confirmatory prospective studies should be
undertaken to ascertain if any of the associated factors are indeed risk factors for injury. In
addition, the odds ratios I report likely overestimate the reported associations since the outcomes
used in my models are not rare events.
Although, the results of this study are limited to the participating dance companies, they may be
generalizable to professional dancers in similar elite ballet companies. Caution should be taken
when attempting to generalize the results to dancers in other modern dance companies as it is
clear that modern dance companies are more heterogeneous than ballet companies. Caution
should also be taken when attempting to generalize to companies that do not operate on a full-
time basis (project based companies) or to freelance dancers. Although this is one of the largest
studies of professional dancers to date, modern dance companies are usually quite small in size
and this led to a lower number of modern dancers compared to ballet dancers in this study. Small
sample size may account for the difficulty in multivariable analysis in modern dancers. I strived
to obtain at least one modern and ballet company in each of the countries however the number of
larger modern companies in each country is limited and I was therefore unable to recruit a
modern dance company in Denmark. Additionally, I was unable to include a ballet company in
Israel.
Additionally, my sample was too small to attain sufficient power to perform multi-level
modeling to compare higher order factors such as country (societal) and dance company factors.
I was unable, therefore, to fully analyze company and country level data to determine its
association with injury in dancers. In addition to company and country level contextual data, it is
possible that other factors that I did not measure such as psychosocial/psychological factors may
play a role in injury in dancers. These factors have recently been explored in studies of Korean
dancers and should be studied in future studies of professional dancers in other countries. 31, 34
93 Following the instructions of the research ethics board, I could not contact or identify those
dancers who did not participate; therefore I do not have any information regarding these dancers.
It is possible that these dancers may have been injured. However, every attempt was made to
capture all dancers who were off work on the date of the survey distribution. These dancers were
mailed surveys in order to minimize any “healthy worker effect” in the results of this study. If
indeed a “healthy worker effect” came into play in this study, then the reported prevalence
estimates would be lower than the true estimate. This may have been the case with the lower
participation rate in the Kibbutz Contemporary Dance Companies and I have reported alternate
prevalence rates with the assumption that dancers who did not participate were injured. The true
estimates are likely somewhere between these two estimates.
It must also be stressed that in self-reported survey based cross-sectional studies, the potential for
misclassification of injury does exist. The self-reported injury outcome is injury from the
dancer’s perspective. The dancer was not given a specific definition of injury and no specific
diagnoses were made by health professionals. I have reported an alternate injury outcome, using
the SEFIP. Although this has been validated for use in dancers, no tool is perfect, and it is indeed
possible that misclassification of injury occurred using this outcome measure as well.
94
4.4 Future Directions
Due to the high prevalence of dance-related injury, further research is essential to investigate
possible interventions to help control injury and understand the long-term implications of injury
in professional dancers. Large prospective studies are needed to clearly identify risk factors that
are associated with injury in dancers. The use of an injury registry would allow researchers to
measure dance exposure and risk factors for injury providing important information for
professional dance companies. The associated factors identified in this study are only one piece
of the dance injury puzzle. Further research should focus on societal and company level factors
making use of multi-level modeling. Additionally, psychological and psychosocial factors and
their relationship with injury should be investigated in this population. Qualitative studies may
be used to further investigate dancers’ attitudes and perceptions of injury, identify barriers to
reporting injuries, and how best to make dancers feel less vulnerable when reporting their
injuries. Research into pain medication use in professional dancers and possible adverse effects
is warranted given the high prevalence of dancers using these medications.
95
Chapter 5: Conclusions
The prevalence of musculoskeletal pain and injury in professional ballet and modern dancers is
high. Professional ballet dancers suffer mostly from injuries to the lower limb and low back. The
types of injuries professional modern dancers suffer from vary among companies. The majority
of reported injuries are chronic in nature in both ballet and modern dancers. The results suggest
that modern dancers are less likely or able to take time off work due to injury. Soloist and
principal ballet dancers are more likely to be injured than corps de ballet dancers for self-
reported injury. Additionally, the number of years dancing professionally was positively
associated with injury in ballet dancers using a SEFIP score of ≥3 as the outcome.
The attitudes and perceptions towards injury vary in this population. Some dancers are
continuing to dance with pain and injury possibly as a result of these attitudes or fears of having
to stop dancing. This may potentially put these dancers at risk for further or greater injury.
Additionally, more than 15% of injured professional dancers are not reporting their injuries for a
variety of reasons including not wanting to have to stop dancing. Measures to support this subset
of injured professional dancers are necessary. Professional ballet and modern dancers are using
high levels of pain medications especially in Canada. Further research into dancers’ pain
medication use is essential. Large scale prospective studies are recommended to further
investigate risk factors for injury in professional dancers. Additionally qualitative studies are
recommended to further investigate dancers’ attitudes and perceptions of injury and how best to
support dancers afraid to report injury. Most importantly, there is an urgent need to investigate
interventions to help control injury and understand the long-term implications of these conditions
in this population.
95
96
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Appendix 1: Electronic Database Search Strategies
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Appendix 3 : Research Ethics Board Approvals
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Professor Jan Hartvigsen Institut for Idræt og Biomekanik Syddansk Universitet Campusvej 55 5230 Odense M Sendt til: [email protected]
Ovennævnte projekt er den 23. august 2007 anmeldt til Datatilsynet efter persondatalovens1 § 48, stk. 1. Der er samtidigt søgt om Datatilsynets tilladelse. Det fremgår af anmeldelsen, at De er dataansvarlig for projektets oplysninger. Behandlingen af oplysningerne ønskes påbegyndt snarest og forventes at ophøre 31. januar 2010. Oplysningerne vil blive behandlet på følgende adresse: Institut for Idræt og Biomekanik, Syddansk Universitet, Campusvej 55, 5230 Odense M. Oplysningerne vil endvidere blive behandlet ved det deltagende center: Toronto Western Hospital, 399 Bathurst Street, Felle Pavilion 4-114, Toronto, Ontario, Canada M5T 2S8.
5. november 2007 Vedrørende anmeldelse af: Perception of Musculoskeletal Injury in Professional Dancers
Datatilsynet Borgergade 28, 5. 1300 København K CVR-nr. 11-88-37-29 Telefon 3319 3200 Fax 3319 3218 E-post [email protected] www.datatilsynet.dk J.nr. 2007-41-0979 Sagsbehandler Maiken Toftgaard Knudsen Direkte 3319 3248
TILLADELSE Datatilsynet meddeler hermed tilladelse til projektets gennemførelse, jf. persondatalovens § 50, stk. 1, nr. 1. Datatilsynet fastsætter i den forbindelse nedenstående vilkår: Generelle vilkår
1 Lov nr. 429 af 31. maj 2000 om behandling af personoplysninger med senere ændringer.
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Tilladelsen gælder indtil: 31. januar 2010 Ved tilladelsens udløb skal De særligt være opmærksom på følgende: Hvis De ikke inden denne dato har fået tilladelsen forlænget, går Datatilsynet ud fra, at projektet er afsluttet, og at personoplysningerne er slettet, anonymiseret, tilintetgjort eller overført til arkiv, jf. nedenstående vilkår vedrørende projektets afslutning. Anmeldelsen af Deres projekt fjernes derfor fra fortegnelsen over anmeldte behandlinger på Datatilsynets hjemmeside. Datatilsynet gør samtidig opmærksom på, at al behandling (herunder også opbevaring) af personoplysninger efter tilladelsens udløb er en overtrædelse af persondataloven, jf. § 70. 1. Professor Jan Hartvigsen er ansvarlig for overholdelsen af de fastsatte vilkår. 2. Oplysningerne må kun anvendes til brug for projektets gennemførelse. 3. Behandling af personoplysninger må kun foretages af den dataansvarlige eller på
foranledning af den dataansvarlige og på dennes ansvar. 4. Enhver, der foretager behandling af projektets oplysninger, skal være bekendt med de fastsatte
vilkår. 5. De fastsatte vilkår skal tillige iagttages ved behandling, der foretages af databehandler. 6. Lokaler, der benyttes til opbevaring og behandling af projektets oplysninger, skal være indrettet
med henblik på at forhindre uvedkommende adgang. 7. Behandling af oplysninger skal tilrettelægges således, at oplysningerne ikke hændeligt eller
ulovligt tilintetgøres, fortabes eller forringes. Der skal endvidere foretages den fornødne kontrol for at sikre, at der ikke behandles urigtige eller vildledende oplysninger. Urigtige eller vildledende oplysninger eller oplysninger, som er behandlet i strid med loven eller disse vilkår, skal berigtiges eller slettes.
8. Oplysninger må ikke opbevares på en måde, der giver mulighed for at identificere de
registrerede i et længere tidsrum end det, der er nødvendigt af hensyn til projektets gennemførelse.
9. En eventuel offentliggørelse af undersøgelsens resultater må ikke ske på en sådan måde, at
det er muligt at identificere enkeltpersoner. 10. Eventuelle vilkår, der fastsættes efter anden lovgivning, forudsættes overholdt.
Elektroniske oplysninger 11. Identifikationsoplysninger skal krypteres eller erstattes af et kodenummer el. lign. Alternativt
kan alle oplysninger lagres krypteret. Krypteringsnøgle, kodenøgle m.v. skal opbevares forsvarligt og adskilt fra personoplysningerne.
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12. Adgangen til projektdata må kun finde sted ved benyttelse af et fortroligt password. Password skal udskiftes mindst én gang om året, og når forholdene tilsiger det.
13. Ved overførsel af personhenførbare oplysninger via Internet eller andet eksternt netværk skal
der træffes de fornødne sikkerhedsforanstaltninger mod, at oplysningerne kommer til uvedkommendes kendskab. Oplysningerne skal som minimum være forsvarligt krypteret under hele transmissionen. Ved anvendelse af interne net skal det sikres, at uvedkommende ikke kan få adgang til oplysningerne.
14. Udtagelige lagringsmedier, sikkerhedskopier af data m.v. skal opbevares forsvarligt aflåst og
således, at uvedkommende ikke kan få adgang til oplysningerne. Manuelle oplysninger 15. Manuelt projektmateriale, udskrifter, fejl- og kontrollister, m.v., der direkte eller indirekte
kan henføres til bestemte personer, skal opbevares forsvarligt aflåst og på en sådan måde, at uvedkommende ikke kan gøre sig bekendt med indholdet.
Oplysningspligt over for den registrerede
16. Hvis der skal indsamles oplysninger hos den registrerede (ved interview, spørgeskema,
klinisk eller paraklinisk undersøgelse, behandling, observation m.v.) skal der uddeles/fremsendes nærmere information om projektet. Den registrerede skal heri oplyses om den dataansvarliges navn, formålet med projektet, at det er frivilligt at deltage, og at et samtykke til deltagelse til enhver tid kan trækkes tilbage. Hvis oplysningerne skal videregives til brug i anden videnskabelig eller statistisk sammenhæng, skal der også oplyses om formålet med videregivelsen samt modtagerens identitet.
17. Den registrerede bør endvidere oplyses om, at projektet er anmeldt til Datatilsynet efter
persondataloven, samt at Datatilsynet har fastsat nærmere vilkår for projektet til beskyttelse af den registreredes privatliv. Indsigtsret
18. Den registrerede har ikke krav på indsigt i de oplysninger, der behandles om den
pågældende.
Videregivelse 19. Videregivelse af personhenførbare oplysninger til tredjepart må kun ske til brug i andet
statistisk eller videnskabeligt øjemed.
20. Videregivelse må kun ske efter forudgående tilladelse fra Datatilsynet. Datatilsynet kan stille nærmere vilkår for videregivelsen samt for modtagerens behandling af oplysningerne. Ændringer i projektet
21. Væsentlige ændringer i projektet skal anmeldes til Datatilsynet (som ændring af eksisterende
anmeldelse). Ændringer af mindre væsentlig betydning kan meddeles Datatilsynet.
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22. Ændring af tidspunktet for projektets afslutning skal altid anmeldes.
Ved projektets afslutning
23. Senest ved projektets afslutning skal oplysningerne slettes, anonymiseres eller tilintetgøres,
således at det efterfølgende ikke er muligt at identificere enkeltpersoner, der indgår i undersøgelsen.
24. Alternativt kan oplysningerne overføres til videre opbevaring i Statens Arkiver (herunder Dansk Dataarkiv) efter arkivlovens regler.
25. Sletning af oplysninger fra elektroniske medier skal ske på en sådan måde, at oplysningerne
ikke kan genetableres. Overførsel af oplysninger til tredjelande
26. Overførsel af oplysninger til tredjelande, herunder til behandling hos databehandler samt til
intern anvendelse i projektet, kræver forudgående tilladelse fra Datatilsynet.
27. Overførsel kan dog ske uden tilladelse, hvis den registrerede har givet udtrykkeligt samtykke til dette. Den registrerede kan tilbagekalde samtykket.
28. Overførsel af oplysninger skal ske med bud eller anbefalet post. Ved elektronisk overførsel skal der træffes de fornødne sikkerhedsforanstaltninger mod, at oplysningerne kommer til uvedkommendes kendskab. Oplysningerne skal som minimum være forsvarligt krypteret under hele transmissionen.
Ovenstående vilkår er gældende indtil videre. Datatilsynet forbeholder sig ret til senere at tage vilkårene op til revision, hvis der skulle vise sig behov for det. Opmærksomheden henledes specielt på, at Datatilsynets vilkår også skal iagttages ved behandling af oplysninger på de deltagende centre mv., jf. de generelle vilkår nr. 4. Datatilsynet gør opmærksom på, at denne tilladelse alene er en tilladelse til at behandle personoplysninger i forbindelse med projektets gennemførelse. Tilladelsen indebærer således ikke en forpligtelse for myndigheder, virksomheder m.v. til at udlevere eventuelle oplysninger til Dem til brug for projektet. En videregivelse af oplysninger fra statistiske registre, videnskabelige projekter m.v. kræver dog, at den dataansvarlige har indhentet særlig tilladelse hertil fra Datatilsynet, jf. persondatalovens § 10, stk. 3. Anmeldelsen offentliggøres i fortegnelsen over anmeldte behandlinger på Datatilsynets hjemmeside www.datatilsynet.dk. Persondataloven kan læses/hentes på Datatilsynets hjemmeside under punktet "Lovgivning".
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Med venlig hilsen Maiken Toftgaard Knudsen
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Appendix 4: Copyright Acknowledgements The use of the Self-Estimated Functional Inability because of Pain (SEFIP) is with permission of
Dr. Eva Ramel.