Comparison of closed and open kinetic chain exercise in the anterior cruciate ligament-deficient knee

Abstract

The purpose of this study was to quantify the amount of anterior tibial displacement occurring in anterior cru ciate ligament-deficient knees during two types of re habilitation exercises: 1) resisted knee extension, an open kinetic chain exercise; and 2) the parallel squat, a closed kinetic chain exercise. An electrogoniometer system was applied to the anterior cruciate ligament- deficient knee of 11 volunteers and to the uninvolved normal knee in 9 of these volunteers. Anterior tibial displacement and the knee flexion angle were meas ured during each exercise using matched quadriceps loads and during the Lachman test. The anterior cru ciate ligament-deficient knee had significantly greater anterior tibial displacement during extension from 64° to 10° in the knee extension exercise as compared to the parallel squat exercise. In addition, the amount of displacement during the Lachman test was significantly less than in the knee extension exercise, but signifi cantly more than in the parallel squat exercise. No significant differences were found between measure ments in the normal knee. We concluded that the stress to the anterior cruciate ligament, as indicated by ante rior tibial displacement, is minimized by using the par allel squat, a closed kinetic chain exercise, when com pared to the relative anterior tibial displacement during knee extension exercise.