Facial Symmetry After Closed and OpenTreatment of Fractures of the Mandibular

Condylar ProcessEdward Ellis III, DDS, MS,* and Gaylord Throckmorton, PhD†

Purpose: This study compares vertical measures of mandibular and facial morphology after open orclosed treatment for fractures of the mandibular condylar process.

Patients and Methods: One hundred forty-six patients (121 male, 25 female), 81 treated by closed and65 by open methods, were included in this study. Towne’s and panoramic radiographs, taken at severalintervals, were used to quantify the displacement of the condylar process fractures. Posteroanteriorcephalograms taken at 6 weeks, 6 months, 1 year, and 2 to 3 years after treatment were used to assessposterior facial height and bigonial and occlusal plane angles. Additionally, panoramic radiographs wereused to assess ramus height at the same periods. Standard statistical methods were used to assessdifferences between groups.

Results: Patients whose condylar process fractures were treated by closed methods had significantlyshorter posterior facial and ramus heights on the side of injury, and more tilting of the occlusal andbigonial planes toward the fractured side, than patients whose fractures were treated by open methods.Most of the asymmetry in patients treated by closed methods was present by 6 weeks after injury.

Conclusions: Patients treated by closed methods develop asymmetries characterized by shortening ofthe face on the side of injury. It is likely that loss of posterior facial height on the side of fracture in thesepatients is an adaptation that helps reestablish a new temporomandibular articulation.

r 2000 American Association of Oral and Maxillofacial Surgeons

It is generally agreed that fractures of the condylarprocess can cause facial asymmetry, and that theearlier in life a condylar process fracture occurs, thegreater the resultant skeletal changes.1-8 The proposedreason for the development of asymmetries is aninterference with growth, resulting either from injuryto the condylar cartilage or from altered function.Destruction of the condyle in the adult is said to resultin more subtle asymmetries because growth hasceased and the mandible has assumed its normal sizeand form.2,9,10 However, several reports in the litera-ture have noted facial asymmetries in adults who

sustained condylar process fractures.11-14 One of thefirst dates back to 1860, when Fountain was wellaware of the ‘‘serious and unsightly’’ deformities thatfollowed condylar fractures in adults, and he noticedand questioned the paucity of reports by othersdescribing their attempts at treating these injuries.15

Closed treatment methods were used in all suchreports. Tasanen and Lamberg16 noted that patientstreated by open reduction and internal wire fixationhad less asymmetry of the face than patients treated byclosed methods. This is not surprising if one believesthat loss of condylar support predisposes to loss offacial height. If so, the reestablishment of ramusheight by open surgery would prevent loss of facialheight. The purpose of this study was to examinevertical facial symmetry in a group of patients treatedby either open or closed methods for fractures of thecondylar process.

Patients and MethodsSUBJECTS

All patients treated in the Division of Oral andMaxillofacial Surgery at the University of Texas South-western Medical Center for unilateral fractures of themandibular condylar process between January 1, 1990and March 31, 1997 were offered the opportunity to

Received from the Division of Oral and Maxillofacial Surgery,

University of Texas Southwestern Medical Center, Dallas, TX.

*Professor, Oral and Maxillofacial Surgery.

†Professor of Cell Biology and Neuroscience.

Supported in part by grants from the AO/ASIF and the United

States Army DAMD17-92-C-2009.

Address correspondence and reprint requests to Dr Ellis: Division

of Oral and Maxillofacial Surgery, University of Texas Southwestern

Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9109;

e-mail: eellis@mednet.swmed.edu

r 2000 American Association of Oral and Maxillofacial Surgeons

0278-2391/00/5807-0004$3.00/0

doi:10.1053/joms.2000.7253

J Oral Maxillofac Surg58:719-728, 2000

719

participate in this study. Inclusion criteria for thisinstitutional review board–approved investigation were1) unilateral fracture of the condylar process; 2) age16 to 70 years; 3) medically able to undergo surgicalintervention; 4) sufficient bilateral dentition to allowmaxillomandibular fixation (MMF) and assessment ofocclusal relationships; 5) no previous history of tempo-romandibular joint dysfunction; 6) no gross pretrau-matic skeletal malrelationship of the jaws; 7) patientconsent to participate. Patients were given incentivefunds ($100) for each postoperative trial in whichthey participated. Standardized radiographs were ob-tained pretreatment, immediately post-treatment, andat 6 weeks, 6 months, and 1, 2, and 3 years after thefracture.

TREATMENT GROUPS

Patients who met the previous criteria and werewilling to participate in the study were placed into 1of 2 treatment groups (closed or open) based on themethod of treatment they selected. Patients whoselected open surgery had arch bars placed on themaxillary and mandibular dentition. All mobile frac-tures of the maxilla and mandible other than thecondylar process fracture were rigidly stabilized usinginternal bone plate or screw fixation. The surgicaltechnique for the condylar process fracture was thesame in all cases and involved a retromandibularapproach.17 Most fractures were stabilized using boneplates without compression (mini-dynamic compres-sion plates, part #443.55, Synthes, Paoli, PA) thatallowed a minimum of two 2.0-mm screws on eachside of the fracture. No postsurgical MMF was used inany patient.

Patients who selected nonsurgical treatment oftheir condylar process fracture underwent applicationof arch bars and rigid internal fixation of otherfractures of the mandible or maxilla. The fracturedcondylar process was not surgically repositioned orstabilized. No patient was placed into postsurgicalMMF. Instead, training elastics were used to assist thepatient to occlude into the proper occlusal relation-ship. This typically consisted of a single Class II elasticon the side of condylar process fracture.

Patients in both groups were instructed in the samephysiotherapy protocol, consisting of occlusal guid-ance with elastics and jaw mobility exercises. Elasticswere used when necessary to help patients achievetheir normal occlusal relationship. Occlusal guidancewas most commonly required in the patients treatedby closed methods, and usually consisted of 1 or 2elastics placed between the maxillary and mandibulararch bars. The elastics were not used to provideMMF—mandibular mobility was desired. Therefore,the lightest forces needed to assist the patient inrestoring their normal occlusal relationship were

used. The arch bars were maintained at least 2 weeksbeyond the time when elastics were no longer neces-sary.

Functional exercises were prescribed to help thepatients achieve a normal range of mandibular mobil-ity. These exercises included maximal mouth open-ing, right and left lateral excursions, and protrusiveexcursions. The postfracture functional exercises weregoal-oriented.

SCORING OF THE OCCLUDING DENTITION

Panoramic radiographs at each period were used toassess the occluding posterior teeth on both thefractured and nonfractured sides. A score of 1 wasgiven if premolars were occluding (ie, no molars). Ascore of 2 was given if molars were occluding,without all premolars in occlusion. A score of 3 wasgiven if both premolars and molars were in occlusion.

MEASUREMENTS OF CONDYLAR PROCESSDISPLACEMENT

A pretreatment panoramic radiograph was used toclassify the level of the condylar process fracture intofractures of the head, neck, and subcondylar region.Fractures occurring at the junction of the head and theneck, essentially an intracapsular fracture, were classi-fied as head fractures. Fractures at or above the levelof the depth of the sigmoid notch, but below thehead, were classified as neck fractures. Fracturesbelow the level of the most inferior point on thesigmoid notch were classified as subcondylar fractures(Fig 1).

To quantify the displacement of the fractured condy-lar processes in the coronal and sagittal planes,radiographs were taken before treatment and at thepostsurgical trial periods. Pretreatment radiographs(ie, post-trauma) were taken in the Radiology Depart-ment of the hospital so the Towne’s images were notstandardized with a cephalostat. At each of the postop-erative testing sessions, standardized Towne’s radio-graphs and posteroanterior (PA) cephalograms wereobtained after placement of the patient’s head in acephalostat on a Quint Sectrograph-200 (Quint Co,Inc, Los Angeles, CA). Additionally, panoramic radio-graphs were obtained pretreatment and at each post-operative trial visit. The radiographs were traced byone operator, checked by another investigator, digi-tized by a single operator using Dentofacial Plannersoftware (Dentofacial Software, Inc, Toronto, Canada),and then the data were stored in a computer.

Measurements of coronal position (from the Towne’simage) and sagittal position (from the panoramicimage) of the condylar processes were made on eachdigitized image. Coronal displacement in the Towne’simage was measured as the angle between a linedrawn between the medial and lateral poles of the

720 FACIAL SYMMETRY

condyle and a line through the middle or lateralsurface of the mandibular ramus (Fig 2). Sagittaldisplacement in the panoramic image was measuredas the angle between a line drawn along the posteriorsurface of the condylar process fragment and a linedrawn through the gonial angle (Fig 3). Ramus heightwas measured on the panoramic image by the perpen-dicular distance between a point located at the mostsuperior aspect of the condyle and the bigonial line(Fig 3).

Radiographic magnification at the postsurgical trialswas the same for both treatment groups. However,the Towne’s radiographs obtained in the radiologydepartment on admission had greater magnificationthan the subsequent images obtained on the QuintSectograph. There was also variability between pa-tients for the Towne’s radiograph that could not bequantified; however, because only angular valueswere being compared, magnification was not a prob-lem.

MORPHOLOGIC MEASURES OF FACIAL SYMMETRY

The PA cephalogram was used to assess verticalfacial symmetry. A horizontal cranial reference linewas drawn tangent to the top of the orbits, or throughthe intersection of the greater wing of sphenoid bonewith the orbit, whichever was clearer (Fig 4). Perpen-dicular distances between this line and gonion (poste-rior facial height) were calculated bilaterally. Thedifference between the posterior facial height on thefractured and nonfractured sides was used as a mea-sure of vertical facial symmetry. The angle betweenthe cranial line and the bigonial line was also calcu-lated. Similarly, the angle between the occlusal planeand the cranial line was calculated.

CORRELATION BETWEEN OCCLUSIONAND FACIAL SYMMETRY

A previous study examined the occlusal results inthis same group of patients.18 Standardized photo-graphs of the patient’s occlusion were independentlyexamined by a surgeon and an orthodontist, and theocclusion was rated as good (normal for the patient),poor (abnormal for the patient), or undecided (couldnot decide from photographs). The orthodontist wasblinded to the patient’s treatment received by onlyhaving the occlusion slides available for examination.The occlusal scores from the orthodontist at the6-week period were used to compare with the amount

FIGURE 1. Illustration showing how condylar process fractures werecategorized into head, neck, and subcondylar. (Reprinted with permis-sion from W.B. Saunders from Ellis E, Palmieri C, Throckmorton GS:Further displacement of condylar process fractures after closed treat-ment. J Oral Maxillofacial Surg 57:1308, 1999.)

FIGURE 2. Illustration showing the method by which coronal displace-ment was quantified in the Towne’s radiograph. A line was drawnbetween the medial and lateral poles of the condyle. Another line wasdrawn tangent to or through the ramus. The inner angle formed by theintersection of the two lines was calculated by computer. The differencebetween the angle on the nonfractured and the fractured sides wasused as a measure of coronal displacement. (Reprinted with permissionfrom W.B. Saunders from Palmieri C, Ellis E, Throckmorton GS:Mandibular motion after closed and open treatment of unilateralcondylar process fractures. J Oral Maxillofac Surg 57:766, 1999.)

721ELLIS AND THROCKMORTON

of condylar process displacement and facial symmetryto determine whether they were related.

ERROR OF METHOD

To identify the accuracy of tracing and of digitizingthe images used in this study, a tomogram, a Towne’s,

and a panoramic radiograph, and a PA cephalometricradiograph were traced and digitized 5 different timesby the same investigator who performed the othertracings and digitizations. The standard deviations foreach test were averaged, giving a linear measurementerror of 60.55 mm and an angular measurement errorof 61.4°. To identify the error from digitizing thetracings, 1 of the tracings was digitized 5 times. Thestandard deviation was 60.17° for angular and 60.4mm for linear variables.

STATISTICAL ANALYSIS

The chi-square test was used to determine whetherthere was a significant difference in the scores foroccluding dentition between the open and closedtreatment groups. A paired t-test was used to deter-mine whether there was any significant differencebetween the presence of occluding dentition on thefractured and nonfractured sides. Student’s t-test wasused to identify differences between the closed andopen groups. Pearson’s correlation coefficients werecalculated to determine the relationship betweendisplacement of the condylar process and morpho-logic variables at each period. Spearman’s rank corre-lation coefficients were calculated to determine therelationship between the occlusion, measures of con-dylar process displacement, and facial symmetry at the6-week period. Repeated measures analysis of vari-ance for the measures of vertical facial symmetry atthe 6-week, 6-month, 1-year, and 2- to 3-year periodswas calculated. A paired t-test was used to determinewhether the displacement of the condylar processeswas significantly different between the preoperativeand 6-weeks postoperative periods. Statistical signifi-cance was defined at P , .05 for all statistical tests.

FIGURE 3. Illustration showing the method by which sagittal displacement and loss of ramus height were quantified on the panoramic radiograph. Areference line was drawn through both gonial angles. Another line was drawn tangent to the posterior border of the condylar process on each side.The difference between the intersection of the tangent to the condylar process and the reference line was calculated by computer. The difference in thisangle between the nonfractured and the fractured side was used as a measure of sagittal displacement. The perpendicular distance between the mostsuperior point on the condyle and the reference line was calculated by computer (dashed line). The difference between the nonfractured and fracturedsides was used as a measure of difference in ramus length (loss of ramus height). (Reprinted with permission from W.B. Saunders from Palmieri C,Ellis E, Throckmorton GS: Mandibular motion after closed and open treatment of unilateral condylar process fractures. J Oral Maxillofac Surg 57:767,1999.)

FIGURE 4. Illustration showing how facial symmetry was evaluatedon posteroanterior cephalogram. A horizontal cranial reference linewas drawn tangent to the top of the orbits, or through the intersection ofthe greater wing of sphenoid bone with the orbit. Perpendiculardistances between this line and gonion (posterior facial height) werecalculated bilaterally. The difference between the posterior facialheight on the fractured and nonfractured sides was calculated as ameasure of vertical facial symmetry. The angle between the cranial lineand the bigonial line was also calculated. Similarly, the angle betweenthe occlusal plane and the cranial line was calculated.

722 FACIAL SYMMETRY

ResultsA total of 157 patients (130 male, 27 female) were

enrolled in this study. Ninety-two were treated by theclosed method, and 65 were treated with an openmethod. Patients with intracapsular fractures wereeliminated from the sample because it was not thoughtthat these 11 patients could have undergone rigidinternal fixation. They were analyzed separately todetermine whether they behaved any differently thandid other patients treated by the closed method(below).

The resultant study sample was 146 patients (121male, 25 female), 81 treated by closed and 65 by openmethods. The left side was involved in 85 cases, andthe right in 61 (Table 1). There were 108 subcondylarand 38 neck fractures. Of the 81 patients in the closedgroup, 26 had fractures of the neck and 55 weresubcondylar; of the 65 patients in the open group, 12had fractures of the neck and 53 had subcondylarfractures. This difference was not a statistically signifi-cant.

Associated mandibular fractures occurred in a largepercentage of cases. In the closed group, 46 of 81patients had concomitant mandibular fractures, and 9had midfacial fractures. In the open group, 41 of 65patients had concomitant mandibular fractures, and 4had midfacial fractures. There was no significantdifference in the incidence of associated fracturesbetween the 2 groups.

Few patients were available for every postsurgicaltrial, and attrition was large at the later periods. Thesample size for the postsurgical periods fell from 113patients at the 6-week trial to 43 patients at the 2- to3-year period (Table 2).

SCORING OF OCCLUDING DENTITION

Most (94%) patients showed scores of 3 on thepanoramic radiographs, indicating a full complementof premolar and molar occlusion in such cases. Therewere no significant differences between treatmentgroups for the scores of occluding dentition, nor werethere significant differences in the occluding dentitionbetween the fractured and nonfractured sides.

DISPLACEMENT OF THE CONDYLAR PROCESSES

Measures of condylar process displacement at theinitial (pretreatment) time showed that patients whosubsequently were in the open treatment group had,on the average, twice the amount of displacement inthe coronal plane than those who subsequently under-went closed treatment (Table 2). There was alsosignificantly greater vertical overlap of the condylarprocess with the ramus in the open treatment group.No significant difference between the 2 groups wasfound in the sagittal displacement of the condylarprocess.

At 6 weeks, the condylar processes were upright inthe open treatment group so that there was a signifi-cant change in the coronal displacement betweenpreoperatively and 6 weeks postoperatively (P , .001).Similarly, there was a significant change in the ramuslength during these same two periods (P , .001). Nosignificant change in the sagittal position of thecondylar process occurred with surgery. The closedtreatment group showed no significant change in anyof the displacement variables from preoperatively to 6weeks postoperatively.

Comparison of displacement variables between theclosed and open treatment groups showed that at 6weeks there was still a statistically significant differ-ence in the coronal position of the condylar processesand in the amount of vertical overlap. However, theclosed treatment group now had the greater displace-ment. There was no significant difference in thesagittal displacement between the 2 groups at 6weeks.

VERTICAL FACIAL SYMMETRY

In general, all measures of vertical facial symmetrywere significantly different between treatment groupsat most periods. There was shortening of the face onthe side of fracture in patients treated by the closedmethod, but not in patients treated by the openmethod. At 6 weeks, the patients treated by the closedmethod already had almost 3 mm of shortening of

Table 1. SAMPLE CHARACTERISTICS

Treatment GroupsClosed Open

Location of fracture*Subcondylar 55 53Neck 26 12

SideRight 37 24Left 44 41

SexMale 69 52Female 12 13

Additional mandibular fractureYes 46 41No 35 24

Location of additional fractureAngle 7 0Angle 1 body 1 1Body 20 24Symphysis 18 16

Associated facial fracture(s) N 5 9 N 5 4ZMC 6 2Le Fort I 2 1Le Fort 1 ZMC 1 1

*The 11 patients with fractures of the condyle are not included inthe Table because they were not involved in the comparisonbetween open and closed treatment groups.

723ELLIS AND THROCKMORTON

Table

2.M

EASU

RES

OF

CO

ND

YLE

DIS

PLA

CEM

ENT

AN

DFA

CIA

LD

IMEN

SIO

NS

Skel

etal

Mea

sure

Pre

trea

tmen

tIm

med

iate

lyP

ost

op

erat

ivel

y6

Wee

ksP

ost

op

erat

ivel

y6

Mo

sP

ost

op

erat

ivel

y1

Yr

Po

sto

per

ativ

ely

2-3

Yrs

Po

sto

per

ativ

ely

Clo

sed

(n5

57)

Mea

n6

SD

Op

en(n

556

)M

ean

6SD

Clo

sed

(n5

43)

Mea

n6

SD

Op

en(n

558

)M

ean

6SD

Clo

sed

(n5

65)

Mea

n6

SD

Op

en(n

556

)M

ean

6SD

Clo

sed

(n5

31)

Mea

n6

SD

Op

en(n

535

)M

ean

6SD

Clo

sed

(n5

30)

Mea

n6

SD

Op

en(n

533

)M

ean

6SD

Clo

sed

(n5

27)

Mea

n6

SD

Op

en(n

516

)M

ean

6SD

Diff

eren

cein

po

ster

ior

faci

alh

eigh

t(n

on

-fxm

inu

sfx

sid

e)*

2.82

mm

62.

730.

02m

m6

1.47

3.88

mm

63.

650.

14m

m6

1.37

2.85

mm

63.

180.

38m

m6

1.16

4.72

mm

63.

100.

08m

m6

1.29

P,

.001

P,

.001

P,

.001

P,

.001

Big

on

iala

ngl

e†2

1.53

°6

1.43

0.00

°6

0.84

22.

17°

61.

952

0.09

°6

0.78

21.

58°

61.

722

0.23

°6

0.67

22.

54°

61.

620.

08°

61.

29P

,.0

01P

,.0

01P

,.0

01P

,.0

01O

cclu

sive

pla

ne

angl

e‡2

0.91

°6

1.28

0.26

°6

0.84

21.

44°

61.

510.

04°

60.

692

0.85

°6

1.28

20.

05°

60.

602

1.20

°6

1.32

0.31

°6

0.69

P,

.001

P,

.001

P,

.01

P,

.001

Co

ron

ald

isp

lace

men

to

fco

nd

yle

(no

n-fx

min

us

fxsi

de)

§

11.3

6°6

17.5

222

.37°

625

.04

16.7

4°6

19.4

60.

83°

65.

9119

.52°

625

.25

3.35

°6

8.20

16.2

8°6

21.6

63.

44°

611

.28

17.4

2°6

21.1

93.

21°

610

.35

17.2

7°6

17.6

21.

57°

65.

99P

,.0

1P

,.0

01P

,.0

01P

,.0

1P

,.0

01P

,.0

01Sa

gitt

ald

isp

lace

men

to

fco

nd

yle

(no

n-fx

min

us

fxsi

de)

\

1.37

°6

12.4

41.

26°

620

.06

5.35

°6

19.5

92.

01°

67.

301.

87°

614

.78

21.

34°

67.

872

3.51

°6

6.58

23.

16°

67.

502

1.59

°6

11.5

42

3.52

°6

8.79

25.

00°

613

.30

22.

79°

69.

10N

SN

SN

SN

SN

SN

SD

iffer

ence

inra

mu

sle

ngt

h(n

on

-fxm

inu

sfx

sid

e)¶

1.80

mm

64.

295.

16m

m6

3.58

2.08

mm

65.

092

0.74

mm

64.

472.

96m

m6

5.00

20.

48m

m6

3.93

4.36

mm

65.

310.

92m

m6

3.58

3.20

mm

65.

420.

86m

m6

3.70

4.04

mm

64.

472.

55m

m6

3.70

P,

.001

P,

.01

P,

.001

P,

.01

P5

.058

P5

.248

*Po

siti

veva

lues

mea

nth

atth

efr

actu

red

sid

ew

assh

ort

erth

anth

en

on

frac

ture

dsi

de.

†Neg

ativ

eva

lues

mea

nth

atth

efr

actu

red

sid

ew

assh

ort

erth

anth

en

on

frac

ture

dsi

de.

‡Neg

ativ

eva

lues

mea

nth

atth

ere

was

a‘‘

can

t’’o

fth

eo

cclu

salp

lan

eto

war

dth

efr

actu

red

sid

e(t

he

max

illar

ym

ola

rw

asm

ore

sup

erio

rly

loca

ted

on

the

frac

ture

dsi

de

rela

tive

toth

en

on

frac

ture

dsi

de)

.§P

osi

tive

valu

esfo

rco

ron

alp

osi

tio

nm

ean

sth

eco

nd

ylar

pro

cess

was

dis

pla

ced

med

ially

.\P

osi

tive

valu

esfo

rsa

gitt

alp

osi

tio

nm

ean

sth

eh

ead

isd

isp

lace

dan

teri

orl

yre

lati

veto

the

nec

ko

fth

eco

nd

ylar

pro

cess

.¶

Po

siti

veva

lues

mea

nth

atth

efr

actu

red

sid

ew

assh

ort

erth

anth

en

on

frac

ture

dsi

de.

724 FACIAL SYMMETRY

facial height on the fractured side. At 6 months, therewas almost 4 mm of shortening, and at 2 to 3 yearsthere was almost 5 mm of shortening. In contrast tothese findings, patients treated by the open methodhad less than 0.5 mm difference in facial height fromone side to the other at all periods. Not surprisingly,the bigonial angles, which used the same skeletallandmarks, paralleled these findings. The occlusalplane angles showed similar but smaller statisticallysignificant differences between treatment groups.

Differences in ramus height from the nonfracturedto the fractured side were significantly different be-tween treatment groups immediately postoperativelyand at 6 weeks and 6 months, but not thereafter.Immediately postoperatively, the fractured side ramuswas approximately 2 mm shorter than the nonfrac-tured side in patients treated by the closed method. At6 weeks, the difference was almost 3 mm, and at 6months the difference was 4.4 mm. The differencebetween the fractured and nonfractured sides forpatients treated by the open method was less than 1mm for all periods except at 2 to 3 years. Even thoughthe 1 year and 2- to 3-year periods showed nostatistically significant difference between treatmentgroups, shortening of the ramus tended to be greaterin patients treated by the closed method.

As expected, there were significant correlationsbetween some of the morphologic variables. Forinstance, posterior facial height (difference), bigonialangle, occlusal plane angle, and ramus length (differ-ence) measures were significantly correlated (P , .01to .001) with one another at all time intervals in bothtreatment groups. The only exception was the correla-tion between ramus length and occlusal plane angle,which was significant only at the 6-month period.There were no significant correlations between mea-sures of condylar process displacement and facialmorphology.

Repeated measures analysis of variance for poste-rior facial height at times 6 weeks, 6 months, 1 year,and 2 to 3 years showed a significant change over timefor patients treated by the closed method (P , .001).Fifteen cases had data at all of these times, with meanlosses of 2.48 mm, 3.43 mm, 3.36 mm, and 4.29 mm,respectively. No differences over time were noted forthe patients treated by the open method.

RELATIONSHIP BETWEEN OCCLUSIONAND FACIAL SYMMETRY

There were no significant correlations between thequality of the occlusion (normal vs poor), measures ofcondylar process displacement (coronal and sagittaldisplacement, difference in ramus height), and mea-sures of facial symmetry (posterior facial height,bigonial and occlusal plane angles) at the 6-weekperiod in either open or closed treatment groups.

PATIENTS WITH FRACTURES OF THE HEADOF THE CONDYLAR PROCESS

Eleven patients were treated for fractures of thehead of the condylar process (intracapsular), andwere all treated by the closed method. Table 3 lists thedemographic characteristics of this group of patients.In spite of the finding that, as a group, the condylarheads were more displaced than the fractures in theother patients treated by the closed method (bothsagittally and coronally, P , .01), there was no signifi-cant difference in facial morphology when they werecompared.

DiscussionThe results of this study show that there is a clear

difference in posterior facial height between patientstreated by closed methods and those treated by openmethods. Those treated by the closed method, as agroup, had a significant amount of shortening of theposterior facial dimension on the side of injury,whereas, as a group, those treated by the openmethod, showed no asymmetries. Although suchchanges are well documented when fractures of thecondylar process occur in young, growing patients,1-8

there is sparse documentation concerning such alter-ations in adults. The incidence of facial asymmetry inadults treated for unilateral condylar process fracturesby closed methods is low in those studies that havecommented on facial symmetry.11-15 However, thesestudies were not specifically designed to quantita-tively evaluate facial symmetry. Instead, qualitativeassessment of the external appearance of the face wasthe means for documenting whether an asymmetrywas present. Because PA cephalograms were mea-sured in this study, more facial asymmetry thanpreviously documented was found.

The results of this study clearly show that surgical

Table 3. CHARACTERISTICS OF SAMPLE WITHFRACTURES OF THE HEAD OF THE CONDYLARPROCESS (N 5 11)

SideRight 7Left 4

SexMale 9Female 2

Additional mandibular fractureYes 3No 8

Location of additional fracturesBody 2Symphysis 1

Associated facial fracture(s)ZMC 1

725ELLIS AND THROCKMORTON

reestablishment of vertical ramus height by openreduction and internal fixation of the condylar processfracture results in normal facial symmetry in mostpatients up to 3 years postinjury. The average differ-ence in posterior facial height between the 2 sideswas less than 0.5 mm at all periods in patients treatedby the open method. However, there were a fewpatients who had greater differences (Fig 5A). It isplausible that these patients had some resorption ofthe condylar process from the effects of injury or opensurgical treatment. However, overall asymmetries wereuncommon in these patients.

These results are similar to those of Zhang and

Obeid,19 who performed a study comparing openreduction and internal fixation with closed treatmentof unilateral condylar process fractures in rabbits.Those treated by the closed method showed loss oframus height, whereas those treated by open reduc-tion and internal fixation with a miniplate showed noasymmetries.

The most interesting finding of this study is the lossof posterior facial height in most patients treated bythe closed method. Although this was slight in somepatients, it was relatively large in many others (Fig 5B).Most loss of posterior facial height was already presentat the 6-week period, indicating that the process

FIGURE 5. Graphs of differencein posterior facial height betweennonfractured to fractured sides forpatients treated by the open (A)and closed method (B).

726 FACIAL SYMMETRY

responsible for the loss occurs relatively rapidly.There was a significant shortening of the posteriorfacial dimension that occurred from 6 weeks to 6months, indicating that the process continued for atleast the first 6 months and in many instances beyond.

Although many factors may be involved in loss ofposterior facial height after closed treatment of condy-lar process fracture, undoubtedly a major factor is lossof skeletal support between the mandibular angle andthe temporomandibular joint. The pull of the elevatormuscles and contraction of scar tissue within thefracture gap may be other factors.

Loss of posterior facial height after unilateral condy-lar process fracture also has been demonstrated inanimal studies. Heurlin et al20 performed unilateralcondylar fracture-dislocations in adult monkeys forwhich no treatment was provided. Twelve monthslater the animals showed asymmetry, with mandibulardeviation toward the side of surgical fracture. Theramus on the affected side was shortened whencompared with the nonfractured side. The total facialheight on the operated side also was decreased, withmost of the deformity occurring in the mandible.Although the basal bone showed a shift toward theaffected side, the occlusion remained normal.

Sarnat and Muchnic21 performed a similar study inadult squirrel monkeys but used unilateral condylec-tomy instead of fracture dislocation. Two years later,facial height was decreased on the operated side. Thevertical dimension of the maxilla was also shorter onthat side, as was the ramus. Facial asymmetry wasthereby produced by condylectomy, in spite of thefinding that the occlusion remained normal. Theyhypothesized that loss of the anatomic integrity of thetemporomandibular joint, loss of function of thelateral pterygoid muscle, altered function of the me-dial pterygoid, masseter, and temporalis muscles, andestablishment of a false joint all served to modify thedirection and amount of muscular pull, resulting inaltered position and motion of the mandible. Reducedjaw muscle mechanical advantages and altered jawmuscle force directions have been reported in bilat-eral condyle fracture patients.22

To determine whether facial changes after condylec-tomy were attributable to alteration in biomechanicsor loss of the condyle, Sorensen and Laskin23 made acomparison between the changes in adult monkeysafter unilateral condylectomy and after surgical reduc-tion of ramus height without removal of the condyle.23

The latter procedure involved excision of a segmentof bone in the subcondylar region followed by osteo-synthesis between the condylar process and theramus, effectively shortening the ramus. The resultsshowed posterior facial shortening on the operatedside in both groups. Because the skeletal changes inboth groups were similar, it is likely that loss of

posterior vertical ramus dimension is the reason forfacial asymmetry. With loss of posterior ramus height,muscle forces are transferred to the posterior teeth,which act as a new fulcrum. It appears as though theteeth are not able to resist these continuous forces andwere displaced apically. This probably accounted forthe decreased maxillary and mandibular body heightin the posterior area on the operated side. The apicaldisplacement of teeth allowed the mandible to movesuperiorly on the operated side while maintaining theocclusion.

The data from the patients treated by the closedmethod in the current study show that apical displace-ment of the teeth occurs in both the maxilla and themandible. Not only did the bigonial angle change,becoming canted toward the fractured side, but so didthe occlusal plane angle. The amount of occlusalplane angle change was approximately half of thechange in the bigonial angle. This indicates thatapproximately equal amounts of dental intrusion oc-curred on the side of fracture in both jaws. The findingof maxillary dental intrusion should not be surprisinggiven the probable mechanism of premature contactof the posterior dentition on the side of fracture, withresultant intrusive forces from contraction of themuscles against a ramus without a firm temporoman-dibular articulation. One might hypothesize that it isthe ability of the teeth to intrude that allows recoveryof a good occlusal relationship after fracture. If thedentition did not intrude, it might act as a fulcrum forthe shortened ramus, causing premature contact andcreation of an anterior open bite. The intrusion of theteeth and resultant asymmetry therefore should beregarded as a favorable biologic adaptation.

A question that arises is whether the patientstreated by the closed method would have developedfacial asymmetry had they been placed into MMF forseveral weeks after surgery. Although a commontreatment for condylar process fractures in adults,MMF was not used in any patient in this study. Instead,elastics were applied to assist the patient in obtainingproper occlusion. Typically, 1 Class II elastic wasapplied on the side of the fracture. The elastics did notcause eruption of the dentition, because the dataindicate that the teeth moved apically within thealveolus. One might argue that because the patientswere able to carry their mandibles in ‘‘rest position’’most of the time, the teeth were not subjected toloading by the shortened ramus as much as theywould have been had they been placed into MMF.Patients placed into MMF therefore might developeven more facial asymmetry than seen in this study.

The position of the fractured condylar process andthe degree of displacement and dislocation have beenused in deciding whether treatment should be by aclosed or open method.24-34 For instance, Mikkonen et

727ELLIS AND THROCKMORTON

al24 and Klotch and Lundy29 opened fractures ifcondylar displacement was greater than 45° in eitherthe coronal or the sagittal plane and Widmark et al33

opened fractures with greater than 30° coronal orsagittal displacement. Joos and Kleinheinz34 recom-mended open treatment for fractures with greaterthan a 37° coronal tilt because they found that verticalregenerative capability of the condylar process wasless in such cases.34 Such suggestions are usually basedon perceived occlusal outcomes. Does difficulty inrestoring the occlusion go hand-in-hand with loss offacial height?

A previous study of the same patients as in thecurrent study showed a significant and positive corre-lation between condylar process displacement andmalocclusion in patients treated by the closed meth-od.18 Surprisingly, the asymmetry that developed inthe patients treated by the closed method had nostatistical correlation to the displacement of the condy-lar fragment either immediately after injury or atperiods when facial dimension was assessed. Thisindicates that the ability to maintain a good occlusionis not related to whether there is a loss of posteriorvertical dimension. Therefore, the possibility of losingposterior facial height in patients treated by a closedmethod may be more a biologic curiosity than anundesirable outcome. However, such changes couldaffect neuromuscular balance and temporomandibu-lar joint loads. Functional parameters and biomechan-ics on these patients is the subject of future research.

References1. Thompson JR: Asymmetry of the face. J Am Dent Assoc

30:1859, 19432. Walker DG: Fifty cases demonstrating arrest in development.

Dent Practit Dent Rec 7:160, 19563. Sarnat BG: Facial and neurocranial growth after removal of the

mandibular condyle in the Macaca rhesus monkey. Am J Surg94:19, 1957

4. Coccaro PJ: Restitution of mandibular fossa after condylarinjury in infancy (a 7-year study of a child). Am J Orthod 55:32,1969

5. Gilhuus-Moe O: Fractures of Mandibular Condyle in the GrowthPeriod. Oslo, Norway, Universitetforlaget, 1969

6. Ferguson MWJ, Whitlock RIH: An unusual case of acquiredunilateral condylar hypoplasia. Br J Oral Surg 16:156, 1978

7. Proffit WR, Vig KWL, Turvey TA: Early fracture of the mandibu-lar condyles: Frequently an unsuspected cause of growthdisturbances. Am J Orthod 78:1, 1980

8. Yamashiro T, Okada T, Takada K: Case report: Facial asymmetryand early condylar fracture. Angle Orthod 68:85, 1998

9. Thoma KH, Kalil FH: Partial ankylosis due to pseudoarthrosisfollowing fracture through neck of condyle. Am J OrthodontOral Surg 29:550, 1943

10. Berger A: Fractures of the mandibular condyle. J Am Dent Assoc30:819, 1943

11. Malgaigne J: Traite des Fractures et des Luxations. Philadelphia,PA, Lippincott, 1859

12. Cook RM, MacFarlane WJ: Subcondylar fracture of the man-dible: A clinical and radiographic review. Oral Surg 27:297,1969

13. Carlson O, Haverling M, Molin C, et al: Fractures of themandibular condyle. Swed Dent J 1:7, 1977

14. Amaratunga NA: A study of condylar fractures in Sri Lankanpatients with special reference to the recent views on treat-ment, healing and sequelae. Br J Oral Maxillofac Surg 25:391,1987

15. Fountain EJ: A rare form of fracture of the lower-jaw, involvingboth neck and body, treated by a novel method. New York MedJ 3:140, 1860

16. Tasanen A, Lamberg MA: Transosseous wiring in the treatmentof condylar fractures of the mandible. J Maxillofac Surg 4:200,1976

17. Ellis E, Dean J: Rigid fixation of mandibular condyle fractures.Oral Surg 76:6, 1993

18. Ellis E, Simon P, Throckmorton GS: Occlusal results after openor closed treatment of fractures of the mandibular condylarprocess. J Oral Maxillofac Surg 58:260, 2000

19. Zhang X, Obeid G: A comparative study of the treatment ofunilateral fractured and dislocated mandibular condyles in therabbit. J Oral Maxillofac Surg 49:1181, 1991

20. Heurlin RJ, Gans BJ, Stuteville O: Skeletal changes followingfracture dislocations: Effect on growth in Macaca rhesusmonkey. Oral Surg 14:1490, 1961

21. Sarnat BG, Muchnic H: Facial skeletal changes after mandibularcondylectomy in the adult monkey. J Anat 108:323, 1971

22. Talwar RW, Ellis E, Throckmorton GS: Adaptations of themasticatory system after bilateral fractures of the mandibularcondylar process. J Oral Maxillofac Surg 56:430, 1998

23. Sorensen DC, Laskin DM: Facial growth after condylectomy orostectomy in the mandibular ramus. J Oral Surg 33:746, 1975

24. Mikkonen P, Lindqvist C, Pihakari A, et al: Osteotomy-osteosynthesis in displaced condylar fractures. Int J OralMaxillofac Surg 18:267, 1989

25. Raveh J, Vuillemin T, Ladrach K: Open reduction of thedislocated, fractured condylar process: Indications and surgicalprocedures. J Oral Maxillofac Surg 47:120, 1989

26. Takenoshita Y, Oka M, Tahshiro H: Surgical treatment offractures of the mandibular condylar neck. J CraniomaxillofacSurg 17:119, 1989

27. Takenoshita Y, Ishibashi H, Oka M: Comparison of functionalrecovery after nonsurgical and surgical treatment of condylarfractures. J Oral Maxillofac Surg 48:1191, 1990

28. Habel G, O’Reagan B, Hidding J, et al: A transcoronoidalapproach of fractures of the condylar neck. J CraniomaxillofacSurg 18:348, 1990

29. Klotch DW, Lundy LB: Condylar neck fractures of the mandible.Otolaryngol Clin North Am 24:181, 1991

30. Konstantinovic VS, Dimitrijevic B: Surgical versus conservativetreatment of unilateral condylar process fractures: Clinical andradiolographic evaluation of 80 patients. J Oral Maxillofac Surg50:349, 1992

31. MacArthur CJ, Donald PJ, Knowles J, et al: Open reduction-fixation of mandibular subcondylar fractures. Arch OtolaryngolHead Neck Surg 119:403, 1993

32. Silvennoinen U, Iizuka T, Oikarinen K, et al: Analysis of possiblefactors leading to problems after nonsurgical treatment ofcondylar fractures. J Oral Maxillofac Surg 52:793, 1994

33. Widmark G, Bagenholm T, Kahnberg KE, et al: Open reductionof subcondylar fractures. Int J Oral Maxillofac Surg 25:107,1996

34. Joos U, Kleinheinz J: Therapy of condylar neck fractures. Int JOral Maxillofac Surg 27:247, 1998

728 FACIAL SYMMETRY