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 DOI: 10.3113/FAI.2009.0057

2009 30: 57Foot Ankle IntOscar Castro-Aragon, Santaram Vallurupalli, Meredith Warner, Vinod Panchbhavi and Saul Trevino

Ethnic Radiographic Foot Differences  

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FOOT & ANKLE INTERNATIONAL

Copyright 2009 by the American Orthopaedic Foot & Ankle SocietyDOI: 10.3113/FAI.2009.0057

Ethnic Radiographic Foot Differences

Oscar Castro-Aragon, MD; Santaram Vallurupalli, MBBS; Meredith Warner, MD; Vinod Panchbhavi, MD; Saul Trevino, MDGalveston, TX

ABSTRACT

Background: The prevalence of foot and ankle conditions variesamong different ethnic groups. It is not known if this differenceis due to any distinctive skeletal morphological characteristicsof the foot. The purpose of this study was to determine ifethnic differences exist in the morphometric measurements onradiographs of the weightbearing foot. Materials and Methods:A morphometric study of weightbearing radiographs of feetwas performed prospectively. Radiographic parameters weremeasured on digital monitors using digital tools. These were thehallux valgus angle (HVA), intermetatarsal angle (IMA), talon-avicular angle (TNA), talonavicular coverage angle (TNCovA),metatarsal span (MS) on anteroposterior (AP) radiographs andtalo-first metatarsal angle (T-1stMTA), calcaneal pitch (CP),and lateral talocalcaneal angle (LTCA) on lateral radiographs.Results: A total of 237 feet in 126 patients (45 African Amer-icans, 59 Caucasians, and 22 Hispanics) were studied. Statis-tically significant differences were found in the CP, LTCA,and MS. African Americans have significantly lower CP thanCaucasians (p < 0.0001). African Americans have significantlylower CP than Hispanics (p < 0.0016). Caucasians have signifi-cantly higher TCA than African Americans (p < 0.0004). Maleshave a larger MS than females (p < 0.0001). Conclusion: Thereare differences in the radiographic morphology of feet amongdifferent ethnic groups. A larger prospective community-basedstudy of morphological differences is needed for better under-standing of the genetic and environmental factors influencingthe prevalence of foot and ankle conditions. Clinical Relevance:The clinical relevance between having a lower CP angle anda higher incidence of flat feet in African Americans warrantsfurther investigation. It is not known if there is a relationshipbetween posterior tibialis insufficiency and low CP.

No benefits in any form have been received or will be received from a commercialparty related directly or indirectly to the subject of this article.

Corresponding Author:Oscar Castro-Aragon, MDOrthopedic Surgery and RehabilitationPO Box 508-2300Curridabat, San JoseCosta Rica 11801E-mail: castroaragon@gmail.comFor information on prices and availability of reprints, call 410-494-4994 x226

INTRODUCTION

The prevalence of foot and ankle conditions in multi-ethnic communities has been previously studied. Dunn et al.reported that flat feet and bunions are more common inAfrican Americans. Plantar fasciitis and plantar heel pad painare more common among Puerto Ricans when compared tonon-Hispanic whites and African Americans.1 A study inAfrica reported that bunions were significantly more commonin whites than in blacks.3–5 Likewise, they also reportedthat the angle between the first and second metatarsalswas significantly greater in white females than in blackfemales. In children, white girls had the smallest halluxvalgus angles and rural black children had the largest angles.However, by the age of 10 years the mean hallux valgusangle was significantly greater in white girls than in blackgirls. This difference was maintained and even increasedduring adolescence, which may predispose them to halluxvalgus.3–5

Since some conditions are more prevalent in certain ethnicgroups, they may have a morphological predisposition tothese conditions.1,3–7,12 The purpose of this study was todetermine if morphological differences exist among ethnicgroups in the linear and angular measurements on weight-bearing radiographs of the foot.

MATERIALS AND METHODS

Approval from the authors’ Institutional Review Boardwas given for this study. A consecutive series of patients wasobtained from UTMB’s outpatient Foot and Ankle Clinic.Bilateral foot radiographs were taken in a standardizedfashion in patients who were more than 17 years of age andwhose chief complaint was not associated with hallux valgusor flat foot deformity. Patients were excluded if they hadsymptomatic or severe hallux valgus, posterior tibial tendondysfunction, fractures, prior surgery, neuropathic deformityor amputations of the lower extremity. The patient’s demo-graphic information, including age, gender, and ethnicitywas collected. The method of measuring the radiographic

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58 CASTRO-ARAGON ET AL. Foot & Ankle International/Vol. 30, No. 1/January 2009

Fig. 1: AP X-ray showing the hallux valgus angle (HVA).

Fig. 2: AP X-ray showing the intermetatarsal angle (IMA).

parameters on the digital monitors using digital tools wasstandardized. The radiographic parameters were measured onthe Picture Archiving and Communication System (PACS)using Kodak direct view web software version 5.2.1. Thiswas done by two foot and ankle fellows who were blinded tothe patient’s ethnicity. The radiographic parameters measuredwere the hallux valgus angle (HVA, Figure 1), intermetatarsal

Fig. 3: AP X-ray showing the talonavicular angle (TNA).

Fig. 4: AP X-ray showing the talonavicular coverage angle (TNCovA).

angle (IMA, Figure 2), talonavicular angle (TNA, Figure 3),talonavicular coverage angle (TNCovA, Figure 4), metatarsalspan (MS, Figure 5) on anteroposterior (AP) radiographs andtalo first metatarsal angle (T-1stMTA, Figure 6), calcanealpitch (CP, Figure 7), lateral talocalcaneal angle (LTCA,Figure 8) on the lateral radiographs. The parameter called“metatarsal span” is the distance between the most prominentpoints on the head of first and fifth metatarsals on the weight-bearing AP radiographs.9 All the other angular and linear

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Foot & Ankle International/Vol. 30, No. 1/January 2009 ETHNIC FOOT DIFFERENCES 59

measurements were measured using standardized techniquesdescribed in the literature.2,13

Statistical analysis was performed using PC-SAS (SASInstitute, Cary, NC). A two-way ANOVA using the ProcGLM (General Linear Model) in Pc-SAS was used to testfor differences. The ANOVA procedure accounts for thestandard error and deviation due to population size. Thedifferences were verified by examining the standard errorof the mean and the confidence intervals for each of thestatistically different variables. With the given sample sizes,we obtained more than 80% probability (power) of detecting

Fig. 5: AP X-ray showing the metatarsal span (MS).

Fig. 6: Lateral X-ray showing the talo-first metatarsal angle (T-1stMTA).

Fig. 7: Lateral X-ray showing the calcaneal pitch (CP).

Fig. 8: Lateral X-ray showing the lateral talocalcaneal angle (LTCA).

differences of one standard deviation or more between thegroups.

RESULTS

A total of 237 feet in 126 patients including 45 AfricanAmericans, 59 Caucasians, and 22 Hispanics were studied.The average age of the study population was 54.7 ± 14.4years. The average ages for African Americans was 52.8 ±12.3 (males 51.5 ± 15.1, females 54.8 ± 9.9) years, theaverage age for Caucasians was 54.6 ± 15.5 (males 53.8 ±16.0, females 52.7 ± 15.6) years, and for Hispanics it was54.7 ± 15.5 (males 55.9 ± 19.4, females 53.7 ± 11.9) years.With the exception of HVA, the average values of allparameters that were measured were within the normal range(Table 1). Statistically significant differences were found inCP, LTCA, and MS. African Americans have significantlylower CP than Caucasians (p < 0.0001). African Americanshave significantly lower CP than Hispanics (p < 0.0016).Caucasians have significantly higher TCA than African

Table 1: Mean radiographic angular and linear measurements

HVA IMA T1st CP IMS TCA TNA TNCovA

AfricanAmericans

17.4 (7.9) 8.7 (2.9) 7.2 (6.0) 14.0 (5.8) 9.1 (1.0) 39.1 (5.7) 75.6 (12.6) 16.3 (8.7)

Caucasians 16.3 (7.8) 9.5 (3.1) 5.3 (4.5) 20.8 (5.0) 8.7 (0.8) 45.2 (5.7) 74.4 (7.5) 16.1 (8.4)Hispanics 15.4 (7.9) 10.0 (3.0) 5.9 (4.4) 19.3 (4.0) 8.8 (0.8) 3.0 (4.6) 77.2 (8.0) 13.0 (8.3)

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60 CASTRO-ARAGON ET AL. Foot & Ankle International/Vol. 30, No. 1/January 2009

Table 2: Calculated p values from ANOVA analysis of radiographic angular and linearmeasurements

VariableDifferences among

ethnic groupsDifferences betweenmales and females

Gender differences within same ethnic group

HVA 0.41 0.07 0.33IMA 0.23 0.99 0.41T-1ST MTA 0.25 0.81 0.02CP < 0.0001 0.68 0.14LTCA < 0.0004 0.64 0.73MS 0.40 < 0.0001 0.71TNA 0.87 0.70 0.08TNCovA 0.42 0.36 0.39

Americans (p < 0.0004). Males have a larger MS thanfemales (p < 0.0001) (Table 2).

DISCUSSION

Calcaneal pitch and the lateral talocalcaneal angle arestatistically different among different ethnic groups. In ourstudy, Caucasians had a significantly greater calcaneal pitchthan African Americans and Hispanics. African Americanshad the lowest calcaneal pitch of all. Caucasians had a signif-icantly higher lateral talocalcaneal angle than African Amer-icans. Males had higher metatarsal span than women amongall ethnic groups. This may be because, in general, maleshave larger feet. None of the other radiographic parametersmeasured among different ethnic groups showed any statisti-cally significant differences. In addition, there were no statis-tically significant differences between males and femalesin the entire study population; nor were there any differ-ences between males and females within the same ethnicgroup. With the exception of MS, none of the parameters wemeasured was statistically different between left and rightfeet. In accordance with previous studies, we did not findany intermetatarsal or hallux valgus angle differences amongthe different ethnic groups.3–5

The 1990 National Health Interview survey reported thatthe incidence of flatfeet is 7 per 1000 under the age of 5 yearsand increases up to 20 per 1000 for the population betweenages 18 to 24 years. After that age, the reported incidence isrelatively constant. This report also stated that blacks havea higher incidence of flat feet than whites, but there is nodifference in the incidence of flat feet between males andfemales.7 An epidemiological survey of foot problems inthe continental United States from 1978 to 1979 reportedthat the incidence of flat feet in white women is relativelyconstant between 1:9 to 1:6 for all ages, but the incidenceof flat foot in blacks increases from 1:7 to 1:2 from age 4 to60+ years.6 It is unknown if the lower CP among AfricanAmericans is a risk factor for pathology. We do not know

if CP progressively lowers during adolescence in AfricanAmericans or if African Americans are born with lower CP,which predisposes them to flat feet in later ages. CP andage do not have any linear correlation in our study group.Further studies with larger sample sizes are needed in thecommunity to correlate flat feet with low calcaneal pitch.Pre- and postadolescent age groups should be studied andcompared in order to understand the progress and pathologyof flatfeet. Considering the higher prevalence of flatfeet inobese, preschool-aged children, when compared to normal-weight children, one of the confounding factors in the presentstudy may be the weight of the patient as they might differin the weight profile.10 It was reported that the incidenceof flexible flatfeet is higher among school children who areoverweight, but the incidence or pathological relationshipbetween weight and the pathological or adult acquired flatfeet is unknown.10 Footwear of the study population wasnot recorded; it may also have an important role in flat footpredisposition.11

The lateral talocalcaneal angle increases in flat feet,which may be due to talar pronation and plantarflexion.8 Inour study group, the lateral talocalcaneal angle in AfricanAmericans is smaller than in Caucasians in spite of havinga flat calcaneal pitch. There are no differences in talar headcoverage angles between Caucasians and African Americans,which denotes talar pronation.

A limitation in our study is that the population studiedis derived from patients attending a tertiary foot and ankleclinic. Although this may not be representative of the generalpopulation, we observed significant differences among thethree ethnic groups. We also could not control for the typeof foot pathology for which the patient was having thisradiographic study. Further investigation can be performedby obtaining radiographs of the general population but thiswill arise other ethical issues. In addition, the sample sizeis small even though we achieved significant statisticaldifferences. By increasing the sample size, differences inother radiographic parameters might also become significant.

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Foot & Ankle International/Vol. 30, No. 1/January 2009 ETHNIC FOOT DIFFERENCES 61

CONCLUSION

There are differences in the morphology of feet amongdifferent ethnic groups. The clinical relevance of thesefindings needs further study in conjunction with the pres-ence of pathology. These differences need to be studiedprospectively in the general population for a better under-standing of possible predisposing factors for various footpathologies. Study of foot development during childhoodand adolescence, in conjunction with associated environ-mental factors, may lead us to develop preventive measures.The results of this study may provide data to better under-stand the role of morphological differences in various footpathologies.

REFERENCES

1. Dunn, J; Link, C; Felson, D; et al.: Prevalence of foot andankle conditions in a multiethnic community sample of older adults.Am J Epidemiol. 159:491– 498, 2004. http://dx.doi.org/10.1093/aje/kwh071

2. Gentili, A; Masih, S; Yao, L; Seeger, L: Pictorial review: foot axesand angles. Br J Radiol. 69:968– 974, 1996.

3. Gottschalk, F; Beighton, P; Solomon, L: The prevalence ofhallux valgus in three South African populations. S Afr Med J.60:655– 656, 1981.

4. Gottschalk, F; Sallis, J; Beighton, P; Solomon, L: A comparison ofthe prevalence of hallux valgus in three South African populations. SAfr Med J. 57:355– 357, 1980.

5. Gottschalk, F; Solomon, L; Beighton, P: The prevalence of halluxvalgus in South African males. S Afr Med J. 65:725– 726, 1984.

6. Gould, N; Schneider, W; Ashikaga, T: Epidemiological survey offoot problems in the continental United States: 1978– 1979. Foot Ankle1:8–10, 1980.

7. Greenberg, L; Davis, H: Foot problems in the US. The 1990 NationalHealth Interview Survey. J Am Podiatr Med Assoc. 83:475– 483, 1993.

8. Lee, M; Vanore, J; Thomas, J; et al.: Clinical Practice GuidelineAdult Flatfoot Panel: Diagnosis and treatment of adult flatfoot.J Foot Ankle Surg. 44:78– 113, 2005. http://dx.doi.org/10.1053/j.jfas.2004.12.001

9. Panchbhavi, V; Trevino, S: Evaluation of hallux valgus surgery usingcomputer-assisted radiographic measurements and two direct forefootparameters. J Foot Ankle Surg. 10:59– 63, 2004. http://dx.doi.org/10.1016/j.fas.2004.02.001

10. Pfeiffer, M; Kotz, R; Ledl, T; Hauser, G; Sluga, M: Prevalenceof flat foot in preschool-aged children. Pediatrics. 118:634– 639, 2006.http://dx.doi.org/10.1542/peds.2005– 2126

11. Sachithanandam, V; Joseph, B: The influence of footwear on theprevalence of flat foot. A survey of 1846 skeletally mature persons. JBone Joint Surg. 77B:254– 257, 1995.

12. Viladot, A: Metatarsalgia due to biomechanical alterations of theforefoot. Orthop Clin North Am. 4:165– 178, 1973.

13. Younger, A; Sawatzky, B; Dryden, P: Radiographic assessment ofadult flatfoot. Foot Ankle Int. 26:820– 825, 2005.

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