Abstract
PURPOSE: This study aimed to investigate ankle kinematic alterations in patients with chronic ankle instability (CAI), with or without a concomitant osteochondral lesion of the talus (OLT), during level walking. Unlike previous studies that did not distinguish between isolated CAI and CAI with an OLT, this study used MRI-confirmed OLT diagnosis combined with six-degrees-of-freedom motion analysis to identify OLT-specific kinematic patterns, which may provide novel biomechanical markers to facilitate clinical screening and early diagnosis. METHODS: A total of 33 patients with CAI (15 with an OLT and 18 without an OLT) and 18 healthy controls were enrolled. Ankle kinematics were assessed using a joint motion analysis system during treadmill gait at a self-selected speed. Statistical parametric mapping (SPM) was used to compare kinematic patterns across groups. RESULTS: Compared to healthy subjects, the patients with OLTs demonstrated reduced plantarflexion during the early stance (1%-5%, 9%-10%), initial (67%-83%), and terminal swing (91%-100%) phases of the gait cycle, and the patients with isolated CAI demonstrated reduced distal translation during the initial swing (65%-69%) phase of the gait cycle. The patients with OLTs exhibited decreased a range of motion (ROM) in plantarflexion (9.6°, P < 0.001), internal rotation (3.0°, P = 0.01), and lateral translation (0.3 mm, P = 0.02); in contrast, the patients with isolated CAI showed reduced inversion rotation (3.1°, P = 0.009) and lateral translation (0.4 mm, P < 0.001) compared with healthy controls. CONCLUSION: The presence of osteochondral lesions further exacerbates kinematic abnormalities in ankles with CAI during gait. These distinct kinematic signatures-particularly reduced plantarflexion ROM in patients with OLTs vs. reduced inversion ROM in patients with isolated CAI-may serve as objective clinical markers to distinguish between these conditions, potentially reducing misdiagnosis rates and enabling clinicians to implement targeted rehabilitation strategies to prevent progression to ankle osteoarthritis.