Isokinetic and isometric testing of knee musculature in young female patients with patellofemoral pain syndrome.

By using a Cybex II+ isokinetic dynamometer, we performed isokinetic and isometric tests of the knee musculature in 29 female patients (aged 17-45 years) with patellofemoral pain syndrome (PFPS) and the same number of age- and weight-matched female controls. The pain was unilateral in 11 patients and bilateral in 18. The isokinetic testing was set at speeds of 60 degrees, 120 degrees and 180 degrees/sec; the isometric testing was set at 30 degrees and 60 degrees of knee flexion. The results showed that the lowest torque values occurred on the affected side of the unilateral group, followed by both sides of the bilateral group, the sound side of the unilateral group, and the control group, sequentially. The highest rate of abnormal torque values for all PFPS patients occurred in the quadriceps at 60 degrees/sec of isokinetic contraction: 33%. In this study, five (17%) patients showed abnormal torque curves and 10 (34%) patients complained of pain or soreness at either the lowest speed of isokinetic testing or during the isometric testing of the quadriceps muscles. The bilateral torque difference was highest in the unilateral group.(ABSTRACT TRUNCATED AT 250 WORDS)