Loss of normal knee motion after anterior cruciate ligament reconstruction is associated with radiographic arthritic changes after surgery.

BACKGROUND: Meniscectomy and articular cartilage damage have been found to increase the prevalence of osteoarthritis after anterior cruciate ligament reconstruction, but the effect of knee range of motion has not been extensively studied.

HYPOTHESIS: The prevalence of osteoarthritis as observed on radiographs would be higher in patients who had abnormal knee range of motion compared with patients with normal knee motion, even when grouped for like meniscal or articular cartilage lesions.

STUDY DESIGN: Cohort study; Level of evidence, 3.

METHODS: We prospectively followed patients at a minimum of 5 years after surgery. The constant goal of rehabilitation was to obtain full knee range of motion as quickly as possible after surgery and maintain it in the long term. Range of motion and radiographs were evaluated at the time of initial return to full activities (early follow-up) and final follow-up according to International Knee Documentation Committee (IKDC) objective criteria. A patient was considered to have normal range of motion if extension was within 2° of the opposite knee including hyperextension and knee flexion was within 5°. Radiograph findings were rated as abnormal if any signs of joint space narrowing, sclerosis, or osteophytes were present.

RESULTS: Follow-up was obtained for 780 patients at a mean of 10.5 ± 4.2 years after surgery. Of these, 539 had either normal or abnormal motion at both early and final follow-up. In 479 patients who had normal extension and flexion at both early and final follow-up, 188 (39%) had radiographic evidence of osteoarthritis versus 32 of 60 (53%) patients who had less than normal extension or flexion at early and final follow-up (P = .036). In subgroups of patients with like meniscal status, the prevalence of normal radiograph findings was significantly higher in patients with normal motion at final follow-up versus patients with motion deficits. Multivariate logistic regression analysis of categorical variables showed that abnormal knee flexion at early follow-up, abnormal knee extension at final follow-up, abnormal knee flexion at final follow-up, partial medial meniscectomy, and articular cartilage damage were significant factors related to the presence of osteoarthritis on radiographs. Abnormal knee extension at early follow-up showed a trend toward statistical significance (P = .0544). Logistic regression showed the odds of having osteoarthritis were 2 times more for patients with abnormal range of motion at final follow-up; these odds were similar for those with partial medial meniscectomy and articular cartilage damage.

CONCLUSION: The prevalence of osteoarthritis on radiographs in the long term after anterior cruciate ligament reconstruction is lower in patients who achieve and maintain normal knee motion, regardless of the status of the meniscus.