Background: Early operative treatment of combined anterior cruciate and medial collateral ligament injuries has frequently led to motion complications and slow quadriceps muscle power gains. The purpose of the present study was to evaluate the effect of early repair or nonoperative treatment of a concomitant medial collateral ligament injury on range of motion of the knee and quadriceps muscle strength in patients with combined injuries.

Methods: Forty-seven consecutive patients with combined anterior cruciate and grade-III medial collateral ligament injuries were randomized into two groups. The medial collateral ligament was repaired in Group I (n = 23) and was treated nonoperatively in Group II (n = 24). In both groups, the torn anterior cruciate ligament was treated with early reconstruction. The patients were evaluated on the basis of sequential range-of-motion measurements, the one-leg-hop test, and isokinetic muscle power measurements at the time of follow-up, and the findings were compared between the two treatment groups.

Results: All patients achieved full knee extension. At all follow-up intervals the flexion deficit was greater in the group that had been managed with surgical repair of both ligaments, but the difference was significant only at six weeks (100° compared with 112°; p = 0.009), twelve weeks (119° compared with 128°; p = 0.043), and thirty-six weeks (130° compared with 136°; p = 0.011) after the operation. The difference between the groups was not significant at fifty-two weeks (132° compared with 137°) or 104 weeks (134° compared with 137°). The quadriceps muscle power deficit at fifty-two weeks was 30.7% in the group that had been managed with combined repair and 20.5% in the group that had been managed with anterior cruciate ligament reconstruction only (p = 0.015). At 104 weeks, the deficits were 14.4% and 9.7%, respectively (p = 0.2).

Conclusions: Early operative treatment of combined anterior cruciate and medial collateral ligament injuries is possible without increased long-term mobilization complications. The rehabilitation period is long, and aggressive physiotherapy is recommended. However, nonoperative treatment of the torn medial collateral ligament allows faster restoration of flexion and quadriceps muscle power. Our results favor nonoperative treatment of the torn medial collateral ligament in patients with combined injuries.

Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.