Ankle arthritis has reached a level of significant epidemiological and health-care importance. It is assumed that ankle arthritis will increase in the next decades due to an increase of its post-traumatic etiology group. The main purposes of this investigation were (a) to provide clinical information about ankle arthritis and total ankle replacement (TAR), (b) to provide in vivo biomechanical data in order to quantify the lower leg muscle atrophy in ankle OA, (c) to quantify the muscle rehabilitation after TAR (d) and to quantify gait characteristics of subjects with ankle OA before and after TAR.
Post-traumatic ankle OA featured preferentially a varus ankle alignment. TAR improved the clinical, daily and sports function of ankle OA patients. In normal subjects, a lower leg muscle asymmetry was found for EMG and torque measurements. Ankle OA was associated with atrophy of the lower leg muscles, characterized by a torque decrease and a reduction of EMG intensity and frequency. Further, ankle OA patients showed a pathological gait pattern that was different from normal healthy subjects. Three months after TAR surgery, torque, EMG and gait results reached the highest difference to the results of normal healthy subjects. One year after surgery, TAR patients showed joint torques and EMG intensities for the affected leg that were closer to the results of normal healthy subjects. However, the preoperatively lowered EMG frequency did not change during rehabilitation. The gait characteristics of TAR patients were one year after surgery closer to normal than preoperatively.