Anterior Cruciate Ligament Injury and Radiologic Progression of Knee Osteoarthritis

Background: Knee osteoarthritis after anterior cruciate ligament (ACL) injury has previously been reported. However, there has been no meta-analysis reporting the development and progression of osteoarthritis. Purpose: We present the first meta-analysis reporting on the development and progression of osteoarthritis after ACL injury at a minimum mean follow-up of 10 years, using a single and widely accepted radiologic classification, the Kellgren & Lawrence classification. Study Design: Meta-analysis. Method: Articles were included for systematic review if they reported radiologic findings of ACL-injured knees and controls using the Kellgren & Lawrence classification at a minimum mean follow-up period of 10 years. Appropriate studies were then included for meta-analysis. Results: Nine studies were included for systematic review, of which 6 studies were further included for meta-analysis. One hundred twenty-one of 596 (20.3%) ACL-injured knees had moderate or severe radiologic changes (Kellgren & Lawrence grade III or IV) compared with 23 of 465 (4.9%) uninjured ACL-intact contralateral knees. After ACL injury, irrespective of whether the patients were treated operatively or nonoperatively, the relative risk (RR) of developing even minimal osteoarthritis was 3.89 ( P < .00001), while the RR of developing moderate to severe osteoarthritis (grade III and IV) was 3.84 ( P < .0004). Nonoperatively treated ACL-injured knees had significantly higher RR (RR, 4.98; P < .00001) of developing any grade of osteoarthritis compared with those treated with reconstructive surgery (RR, 3.62; P < .00001). Investigation of progression to moderate or severe osteoarthritis (grade III or IV only) after 10 years showed that ACL-reconstructed knees had a significantly higher RR (RR, 4.71; P < .00001) compared with nonoperative management (RR, 2.41; P = .54). It was not possible to stratify for return to sports among the patients undergoing ACL reconstruction. Conclusion: Results support the proposition that ACL injury predisposes knees to osteoarthritis, while ACL reconstruction surgery has a role in reducing the risk of developing degenerative changes at 10 years. However, returning to sports activities after ligament reconstruction may exacerbate the development of arthritis.