Does ACL Reconstruction Alter Natural History? A Systematic Literature Review of Long-Term Outcomes

Background: Anterior cruciate ligament (ACL) injury can lead to tibiofemoral instability, decreased functional outcomes, and degenerative joint disease. It is unknown whether ACL reconstruction alters this progression at long-term follow-up. Methods: A systematic literature review of the long-term results (minimum follow-up, more than ten years) after operative intra-articular reconstruction of ACL injuries and after nonoperative management was performed to compare (1) knee stability on physical examination, (2) functional and patient-based outcomes, (3) the need for further surgical intervention, and (4) radiographic outcomes. After application of selection criteria, forty patient cohorts with a mean of 13.9 +/- 3.1 years of postoperative follow-up were identified. Twenty-seven cohorts containing 1585 patients had undergone reconstruction, and thirteen containing 685 patients had been treated nonoperatively. Results: Comparison of operative and nonoperative cohorts revealed no significant differences in age, sex, body mass index, or rate of initial meniscal injury (p > 0.05 for all). Operative cohorts had significantly less need for further surgery (12.4% compared with 24.9% for nonoperative, p = 0.0176), less need for subsequent meniscal surgery (13.9% compared with 29.4%, p = 0.0017), and less decline in the Tegner score (-1.9 compared with -3.1, p = 0.0215). A difference in pivot-shift test results was observed (25.5% pivot-positive compared with 46.6% for nonoperative) but did not reach significance (p = 0.09). No significant differences were seen in outcome scores (Lysholm, International Knee Documentation Committee [IKDC], or final Tegner scores) or the rate of radiographically evident degenerative joint disease (p > 0.05 for all). Conclusions: At a mean of 13.9 +/- 3.1 years after injury, the patients who underwent ACL reconstruction had fewer subsequent meniscal injuries, less need for further surgery, and significantly greater improvement in activity level as measured with the Tegner score. There were no significant differences in the Lysholm score, IKDC score, or development of radiographically evident osteoarthritis.