Effect of Delayed Primary Anterior Cruciate Ligament Reconstruction on Medial Compartment Cartilage and Meniscal Health

BACKGROUND: The time required to develop a secondary cartilage or meniscal injury in the medial compartment after anterior cruciate ligament (ACL) injury is not well understood. PURPOSE: To determine the association between time delay until ACL reconstruction and the presence of medial compartment Outerbridge grade 3 or 4 chondral injury or medial meniscal tear requiring treatment. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 609 patients underwent primary ACL reconstruction at a single institution at a median 46 days between injury and surgery (61.4% male; mean age, 26.5 years SD, 11.1). Chondral status was graded according to Outerbridge criteria at the time of surgery. Multivariate regression analysis was used to assess the relationship between time delay until surgery and medial compartment chondral injury or meniscal injury requiring treatment. Adjustment was performed as needed for patient demographics, sporting activity, and prior knee injuries. Time until surgery had a nonlinear association with medial compartment health and was more effectively described in discrete intervals rather than as a continuous variable. The optimal time intervals to predict medial compartment health were determined by comparison of Bayes information criterion values between fully adjusted regression models. RESULTS: = .001). CONCLUSION: From the time of ACL injury, risk of an irreparable medial meniscal tear found at the time of ACL reconstruction is significantly increased by 8 weeks, and risk of high-grade medial chondral damage is increased by 5 months.