Comparison of Metatarsophalangeal and Interphalangeal Joint Angles of the Hallux between Normal and Pes Planus Feet during Toe Curl

Background Foot intrinsic muscles play an essential role in maintaining medial longitudinal arch (MLA) stability and overall foot function. Altered muscle recruitment patterns in individuals with pes planus may influence hallux joint kinematics during functional tasks. Purpose To compare hallux metatarsophalangeal (MTP) and interphalangeal (IP) joint angles, as well as MLA angles, during toe curl between individuals with normal feet and those with pes planus. Study design Cross-sectional comparative study Methods Thirty participants were included (15 with normal feet and 15 with pes planus), classified using the navicular drop test. Hallux MTP and IP joint angles and MLA angles were measured using video-based kinematic analysis during toe-curl performed in a standardized supine position. Independent t-tests were conducted to compare variables between groups, with statistical significance set at p<0.05. Results No significant differences were observed between groups in MTP or IP joint angles during toe-curl (p=0.294 and p=0.083, respectively). The MLA angle was significantly greater in the pes planus group compared with the normal foot group at both rest (p<0.001) and the final position (p=0.001). However, no between-group difference was found in the change in MLA angle (p=0.979). Conclusions Kinematic analysis during toe-curl in a non–weight-bearing position may have limited sensitivity for detecting differences in intrinsic foot muscle function. Further studies are warranted to evaluate these outcomes under more functionally demanding conditions.