ACL Graft Type Effects on Outcomes Were Not Significantly Modified by Medial Collateral Ligament Status in Combined ACL-MCL Injuries: A Multicenter Registry Study From the French Arthroscopic Society.

BACKGROUND: Combined anterior cruciate ligament (ACL) and medial collateral ligament (MCL) injuries are common in pivoting sport athletes and may affect postoperative stability and recovery. Although hamstring autografts are widely used, concerns persist that harvesting the semitendinosus-gracilis complex could impair medial dynamic stabilization in knees with concomitant MCL injury. HYPOTHESIS/PURPOSE: The purpose was to determine whether MCL status modifies the association between ACL graft type and postoperative patient-reported outcomes. It was hypothesized that MCL status would not significantly modify this relationship. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This prospective multicenter registry study included patients undergoing primary ACL reconstruction between January 2020 and June 2022 in French Arthroscopy Society centers. Patients were categorized by medial injury status (isolated ACL, combined ACL-MCL treated nonoperatively, or operatively) and graft type (hamstring vs nonhamstring). The primary outcome was the International Knee Documentation Committee (IKDC) subjective score. Secondary outcomes included Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI), Subjective Knee Value (SKV), and Tegner activity level. Inverse probability weighting based on propensity scores was used to reduce allocation bias. Weighted multivariable regression models included graft type, MCL status, and a Graft × MCL interaction term. RESULTS: Of 722 eligible patients, 489 (67.7%) had complete outcome and covariate data and were included in the primary analysis. Nonhamstring grafts were associated with higher IKDC scores (β = 7.89; 95% CI, 3.45-12.33; P < .001). Isolated ACL injuries showed higher IKDC scores than combined ACL-MCL injuries treated nonoperatively (β = 10.41; 95% CI, 6.48-14.34; P < .001). The Graft × MCL interaction was not statistically significant (operative MCL: β = -7.02; 95% CI, -15.26 to 1.22; P = .095), providing no statistically significant evidence that MCL status modified the association between graft type and IKDC score. Nonhamstring grafts were also associated with higher ACL-RSI (β = 6.15; 95% CI, 0.02-12.28; P = .049) and SKV (β = 8.87; 95% CI, 4.53-13.21; P < .001), whereas no association was observed for Tegner activity level. CONCLUSION: Nonhamstring grafts were associated with higher patient-reported outcome scores overall; however, no statistically significant evidence was found that MCL status modified the association between graft type and outcomes after ACL reconstruction.