Minimum 10-year results after anterior cruciate ligament reconstruction: how the loss of normal knee motion compounds other factors related to the development of osteoarthritis after surgery.

BACKGROUND: Few long-term studies exist that evaluate how the loss of normal knee range of motion affects results after anterior cruciate ligament reconstruction.

HYPOTHESIS: Patients with normal knee motion will have higher subjective scores than patients with less than normal motion.

STUDY DESIGN: Cohort study; Level of evidence, 2.

METHODS: Patients were prospectively evaluated at >10 years after anterior cruciate ligament reconstruction according to International Knee Documentation Committee criteria. Normal knee motion was within 2 degrees of extension (including hyperextension) and 5 degrees of flexion compared with the uninvolved knee. Regression analysis was performed to determine what factors affected subjective scores.

RESULTS: Objective follow-up was obtained on 502 patients at a mean of 14.1 years postoperatively. Regression analysis showed that the most statistically significant factor related to lower subjective scores was lack of normal knee extension; loss of normal flexion was also significant. Patients who had meniscectomy or articular cartilage damage had statistically significantly lower subjective scores if they also had less than normal motion. Ninety-eight percent of patients with intact menisci, normal articular cartilage, and normal knee motion had normal radiographs; 29% of patients with normal motion had less than normal radiographs versus 71% of patients who had less than normal motion. The overall International Knee Documentation Committee objective grade was normal in 48%, nearly normal in 42%, abnormal in 9%, and severely abnormal in 0.5%.

CONCLUSION: The loss of 3 degrees to 5 degrees of knee extension, to include loss of hyperextension, adversely affected the subjective and objective results after surgery, especially when coupled with meniscectomy and articular cartilage damage.