Foot Function in Patients With Surgically Treated Preaxial Polydactyly of the Foot Compared With Age- and Sex-Matched Healthy Controls

Background: Treatment of preaxial foot polydactyly, a duplication of the first ray, consists of excision of an extra ray, aiming to improve shoe fitting and aesthetic appearance, while maintaining foot function. Currently, the effect of excision on foot function and foot-related patient experiences is unclear. Methods: A cross-sectional comparison between 37 children treated for preaxial foot polydactyly and 37 age- and sex-matched healthy controls was performed. Dynamic foot function was assessed using plantar pressure measurements and static foot characteristics by physical examination. Patient-reported outcomes for foot function and footwear were evaluated, using the Oxford Ankle Foot Questionnaire for Children (score, 0-100). Results: Compared with controls, patients had significantly lower median peak pressures at the hallux (148 kPa [IQR, 98-245] vs 272 kPa [IQR, 205-381], P <.001) and significantly higher peak pressures at the second metatarsal (217 kPa [IQR, 147-338] vs 166 kPa [IQR, 141-235], P =.002) and third to fifth metatarsals (214 kPa [IQR, 147-290] vs 161 kPa [IQR, 135-235], P <.001). Additionally, patients had a more medially deviated hallux, both while seated (15 degrees (IQR, 11-20) vs 12 degrees [IQR, 10-15], P =.001) and standing (20 degrees [IQR, 15-26] vs 18 degrees [IQR, 15-20], P =.001). No significant correlation between peak pressure distribution and hallux deviation was found. Patients reported minimal problems with foot function (87.5 [IQR, 64.6-100]), but distinct problems with footwear use (50.0 [IQR, 25.0-100]). Conclusion: Patients with surgically treated preaxial foot polydactyly had a substantially altered plantar pressure distribution with more lateral foot progression than healthy controls. Although an increased hallux deviation was not related to altered foot function, it seemed to be the reason for the patient-perceived problems with footwear. Level of Evidence: Level III, comparative series.