REFLEX INHIBITION OF THE QUADRICEPS FEMORIS MUSCLE AFTER INJURY OR RECONSTRUCTION OF THE ANTERIOR CRUCIATE LIGAMENT

A burst-superimposition technique was used to assess the strength of t he quadriceps femoris muscle in three groups of patients. Group 1 comp rised twenty patients who had had a torn anterior cruciate ligament of the knee and had a reconstruction of the ligament one to six months a fter the injury. Group 2 comprised twelve patients who had had a torn anterior cruciate ligament for an average of three months (a subacute tear). Group 3 comprised eight patients who had had a torn anterior cr uciate ligament for an average of two years (a chronic tear). The pati ents in Groups 2 and 3 had not had an operation for the torn ligament. The patients in Groups 1 and 3 had no evidence of failure of activati on of the involved quadriceps, but nine of the twelve patients in Grou p 2 had reflex inhibition of contraction of the muscle.