Maintenance of hamstring strength following knee surgery.

Following a variety of surgical procedures on the knee, routine clinical Cybex testing demonstrated that the hamstring muscle group loses less strength than the quadriceps group, regardless of whether the hamstrings were exercised during the rehabilitation. Two groups of postsurgical patients were randomly selected to evaluate the effects of surgery on the muscle strength of the quadriceps and hamstrings. Group I (N = 15) underwent arthrotomy and medial meniscectomy. Group II (N = 20) underwent an extraarticular substitution of the anterior cruciate ligament. All subjects were tested on a Cybex II at 60 degrees/s: Group I at 5-10 wk (mean, 7.0), and Group II at 15-22 wk (mean, 18.6). Peak torque for the quadriceps and hamstrings was measured at 30, 60, and 90 degrees. The percent deficits of the quadriceps and hamstrings were analyzed by a three-way ANOVA. The hamstring deficit was significantly less (P = 0.041) than the quadriceps deficit. A significant difference (P less than 0.001) was found between the two surgery groups. No significant difference in percent strength deficit was found at the various joint angles (30, 60, and 90 degrees). Lastly, the factors examined in the ANOVA did not contribute to a significant first or second order interaction. The authors conclude that specific hamstring strengthening postsurgically is not always indicated.