The Effect of Lateral Ankle Ligament Repair in Muscle Reaction Time in Patients with Mechanical Ankle Instability

Abstract

Studies have shown that functional ankle instability can result in prolonged muscle reaction time. However, the deficit in muscle reaction time in patients with mechanical ankle instability (MAI) and the effect of lateral ankle ligament repair on muscle reaction time are unclear. The purpose of this study was to identify the deficit in muscle reaction time, and to evaluate the role of lateral ligament repair in improving muscle reaction time in MAI patients. Sixteen MAI patients diagnosed with lateral ankle ligament tears by ultrasonography and magnetic resonance imaging underwent arthroscopic debridement and open lateral ankle ligament repair with a modified Broström procedure. One day before the operation, reaction times of the tibialis anterior and peroneus longus muscles were recorded following sudden inversion perturbation while walking on a custom walkway, and anterior drawer test (ADT) and American Orthopaedic Foot and Ankle Society (AOFAS) scale score were evaluated. Six months postoperatively, muscle reaction time, ADT and AOFAS scale score were reevaluated, and muscle reaction times in 15 healthy controls were also recorded. Preoperatively, the affected ankles in the MAI group had significantly delayed tibialis anterior and peroneus longus muscles reaction times compared with controls. Six months after the operation, median AOFAS scale scores were significantly greater than preoperatively, and ADT was negative in the MAI group. However, the affected ankles in the MAI group showed no difference in muscle reaction time compared with preoperative values. MAI patients had prolonged muscle reaction time. The modified Broström procedure produced satisfactory clinical outcomes in MAI patients, but did not shorten reaction times of the tibialis anterior and peroneus longus muscles.