Application of Functional Electrical Stimulation in Anterior Cruciate Ligament Rehabilitation

Rupture of anterior cruciate ligament (ACL) in knee is a common sports injury which may cause knee instability and quadriceps atrophy. In order to prevent anterior translation of the tibia during isokinetic training exercises of the quadriceps, a feedback system incorporating functional electrical stimulation (FES) is implemented to replace conventional anti-shear devices. The feedback system modulates FES parameters according to angle position, angle velocity, and torque signals acquired from the isokinetic dynamometer system to induce moderate contractions of the hamstrings to compensate ACL dysfunction and to avoid anterior translation of the tibia during voluntary exercises of the quadriceps. The restriction of tibial anterior translation induced by the feedback system is confirmed by image processing techniques of captured knee joint images during quadriceps contractions, while better results in terms of range of motion and smoothness of torque curves were measured as compared to the conventional device. This new FES system will accelerate functional recovery of quadriceps in athletes who suffer from rupture of ACL by facilitating more efficient rehabilitation exercises of their quadriceps muscles.