J. Leonard Goldner Award 2006: Total Ankle Replacement in Ankle Osteoarthritis: An Analysis of Muscle Rehabilitation

Abstract

The aim of this prospective study was to determine muscle rehabilitation in total ankle replacement (TAR) for unilateral severe ankle osteoarthritis. Fifteen patients were assessed before and after TAR in 3-month intervals up to 1 year. Clinically, the pain score, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle score, ankle range of motion for dorsiflexion and plantarflexion (ROM DF/PF) and the calf circumference difference between the affected and contralateral healthy leg were measured. Radiographic assessment consisted of osteoarthritis grading abd evaluation of TAR loosening or migration. Biochemically, isometric maximal voluntary torque for ankle dorsiflexion and plantarflexion was measured simultaneously with surface electromyography (EMG; mean frequency and intensity) of the anterior tibial, medial gastrocnemius, soleus, and peroneus longus muscles. Data were compared to a group of 15 age-matched and gender-matched normal subjects. From preoperative to 12 months after TAR, improvement was noted in pain scores (from 6.8 to 0.8 points), AOFAS ankle scores (33.7 to 93.3 points), and ROM DF/PF significantly (16.0 to 31.0 degrees). The difference in mean calf circumference between legs decreased not significantly from 2.1 cm to 1.7 cm. The mean DF torque (16.4 to 23.1 Nm) and PF torque (15.8 to 21.6 Nm) of the affected ankle increased significantly. Compared to the contralateral healthy side, the mean EMG intensity recovered. TAR surgery improved muscle function (torque, EMG intensity) in osteoarthritic ankles. However, after 1 year, patients did not reach the level of the contralateral healthy leg, and the EMG frequency remained unchanged.