Timeline for Maximal Subjective Outcome Improvement After Anterior Cruciate Ligament Reconstruction

Abstract

Background: Anterior cruciate ligament (ACL) tears are one of the most common traumatic knee injuries experienced by athletes. Return to sport is considered the pinnacle endpoint among patients receiving ACL reconstruction. However, at the time of return to sport, patients may not be participating at their previous levels of function, as defined by clinical metrics. Purpose: To establish when patients perceive maximal subjective medical improvement according to patient-reported outcome measures (PROMs). Study Design: Systematic review. Methods: A systematic review of the PubMed database was conducted to identify studies that reported sequential PROMs up to a minimum of 2 years after ACL reconstruction. Pooled analysis was conducted for PROMs at follow-up points of 3 months, 6 months, 1 year, and 2 years. Clinically significant improvement was determined between pairs of intervals with the minimal clinically important difference. Results: This review contains 30 studies including 2253 patients who underwent ACL reconstruction. Clinically significant improvement in the KOOS (Knee injury and Osteoarthritis Outcome Score) was seen up to 1 year after ACL reconstruction, but no clinical significance was noted from 1 to 2 years. Clinically significant improvement in the IKDC (International Knee Documentation Committee) and Lysholm questionnaires was seen up to 6 months postoperatively, but no clinical significance was noted beyond that. Conclusion: After ACL reconstruction, maximal subjective medical improvement is established 1 year postoperatively, with no further perceived clinical improvement beyond this time point according to current PROMs. The KOOS may be a more responsive metric to subjective improvements in this patient cohort than other patient-reported outcomes, such as the IKDC and Lysholm. Clinical Relevance: After ACL reconstruction, patients perceive interval subjective improvements until 1 year postoperatively.