The effect of weight-bearing conditions on toe joint angles in healthy volunteers using weight-bearing CT

Abstract Purpose: To determine the effect of weight-bearing (WB) conditions on toe joint angles in healthy volunteers using WB and non-WB (nWB) CT images and to evaluate left and right foot differences. Methods: In twenty healthy volunteers WB and nWB CT images of both feet were acquired. Bones of the forefoot were segmented and the respective bone models were used to calculate angles for the metatarsophalangeal and interphalangeal joints. Results: Metatarsophalangeal joint (MTPJ) angles ranged between 6˚ and 40˚, proximal interphalangeal joint (PIPJ) angles between 0.5˚ and 54˚and distal interphalangeal joint (DIPJ) angles between 1˚ and 46˚.MTPJ angles were significantly smaller in WB compared to nWB conditions in the first four digits. The interphalangeal joint angles of the first digit was in WB conditions significantly larger. No left-right foot differences were found for toe joint angles. Conclusion: Toe joint angles show a wide variety between healthy volunteers although the bilateral symmetry is high. MTPJ angles of the first to fourth toe are smaller under WB conditions, but do not change PIPJ and DIPJ angles compared to nWB conditions.