Predictors of Hallux Valgus: a study of heritability

Hallux valgus is a complex progressive foot deformity of uncertan aetiology. The disorder is characterised by a lateral deviation of the hallux at the first metatarsophalangeal joint; an angle 150 is considered as clinical hallux valgus. A niodel that predicts first metatarsophalangeal joint angle and thus, hallux valgus is potentially very useful; enabling the clinician to idcntify individuals at risk of developing the disorder and to predict prognosis. The aim of this study is to develop such a model. The literature relating to hallux valgus identifies eight potential aetiological factors of hallux valgus. The scientific evidence presented in support of these suspected aetiological factors, and the theories of pathology of hallux valgus in association with these factors were critically evaluated by a review of the literature. Methods to evaluate the significance of these factors in hallux valgus were identified and appraised. These methods were applied to a large sample of genetically related individuals. The genetic and environmental influences affecting first metatarsophalangeal joint angle. pes planus. metatarsal formula, digital formula and first ray neutral position were explored through the statistical analysis of the data obtained from the sample. ‘The results of analyses suggest that all of these variables are gender influenced, multifactorial traits. Further analysis of a subset of data generated a statistical model that relates the degree of hallux deviation at the first inetatarsophalangeal joint (and thus, the degree of hallux valgus) to clinically measurable predictor variables. A further subset of data was applied to test the model. The model was found to accurately predict first metatarsophalangeal joint angle in 92% of cases. Application of the model allows the clinician to evaluate an individual’s risk of developing hallux valgus enabling accurate prognosis. Recommendations for achieving improved prognosis and the implications for future research are proposed