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° of extension (including hyperextension) and 5° 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° to 5° 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.