In vivo kinematics of fixed-bearing total ankle arthroplasty

Background: A good recovery of the physiological mobility of the ankle is an indication of patients’ satisfaction after total ankle arthroplasty, which does not generally match that of other consolidated procedures such as hip and knee replacement. The aim of this study was to investigate the kinematics of the Zimmer Total Metal Total Ankle (ZTMTA) during the different exercises. Methods: Fifteen patients with ZTMTA were enrolled in this study. The patients performed non-weightbearing flexion-extension, stair climbing and descending, and fluoroscopic images were taken to capture the ankle movements. A combined images/three-dimensional models method was used to perform a kinematic analysis. Results: Plantar-dorsiflexion resulted the main plane of movement, with the largest range of motion (ROM) of 23.3 ± 9.0° during flexion-extension. Inversion–eversion and adduction–abduction resulted lower than 10° in any trials. Conclusions: In the investigated population, the ZTMTA allowed a good recovery of the mobility, with ROMs comparable to the healthy subjects.