Torque-velocity relationships of the knee extensor and flexor muscles in individuals sustaining injuries of the anterior cruciate ligament

Muscle deficits in 58 patients with chronic anterior cruciate ligament (ACL) insufficiency were evaluated after completion of a 6 month rehabilitation program. Quadriceps and hamstring torques were measured on a modified Cybex II isokinetic dynamometer. Twenty- nine of our patients were tested just prior to undergoing ACL reconstruction, and patients who were continuing to tolerate their conditions served as controls. For the surgical group, significant quadriceps deficits (P < 0.01) were found for all speeds and at both the 30 and 60° positions. The nonsurgical group had sig nificant deficits at the 30° position at 180°/sec, and at 60° for the 0°/sec and 30°/sec. However, in comparing the two groups no significant differences were noted. Regarding hamstring deficits in the surgical group, significant deficits were seen only at 30° of flexion at 180°/sec. The nonsurgical group had similar deficits. Of interest was the observation that the ham string:quadriceps (H:Q) ratio was found to be both speed-position dependent. Overall, no correlation was found between the pres ence of strength deficits following a rehabilitation pro gram and the need for surgery.