Patellar pain and quadriceps rehabilitation. An EMG study.

Eighteen patients (26 knees) giving a history of patellar dislocation and/or subluxation and continued patellar symptoms underwent evaluation to determine the efficacy of their rehabilitation programs. Four-channel cine-electromyography was utilized to assess the relative muscular effort of the vastus medialis, vastus lateralis, vastus medialis obliquus, and rectus femoris in a series of exercises. Ten degrees of flexion of the knee reduced effective muscle effort in the vasti group to an average of 1/4 of the muscle effort demonstrated in full extension of the knee. No consistent pattern was noted by altering the rotation of the hip from neutral to external or internal rotation. The addition of weight (5 lb) to the ankle did not enhance the muscle effort with the knee in full extension. Quadsets and straight leg-raising exercises in full knee extension offer the best quadriceps rehabilitation program in the patient with a patellar malalignment syndrome and persistent symptoms.