A Case-Control Study Comparing Bone Bruising and Intra-articular Injuries in Patients Undergoing Anterior Cruciate Ligament Reconstruction With and Without Medial Collateral Ligament Tears

BACKGROUND: Concomitant injuries can occur in patients with combined anterior cruciate ligament (ACL) and medial collateral ligament (MCL) tears; however, no studies have compared these injuries in patients undergoing ACL reconstruction with an MCL tear to those with an intact MCL. PURPOSE: To compare bone bruising, meniscus tears, and chondral lesions in patients undergoing ACL reconstruction with an MCL tear (cases) to those with an intact MCL (controls). STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Thirty-two cases and 352 controls were identified from a prospective registry. Bone bruising was confirmed on magnetic resonance imaging, and meniscus tears and chondral lesions were confirmed arthroscopically. Demographics and concomitant injuries were compared between cases and controls using exact chi-square tests. Multivariate logistic regression was used to calculate odds ratios (ORs) and 95% CIs adjusted for age, sex, body mass index, and mechanism and type of injury. RESULTS: Cases had significantly more contact injuries than controls (58.1% vs 21.3%, P < .0001). The prevalence and odds of bone bruising of the lateral tibial plateau (89.7% vs 84.6%; P = .59; OR, 3.53; 95% CI, 0.45-27.71), lateral femoral condyle (82.8% vs 72.8%; P = .28; OR, 1.94; 95% CI, 0.64-5.88), medial tibial plateau (20.7% vs 31.7%; P = 0.29; OR, 0.53; 95% CI, 0.19-1.53), and medial femoral condyle (6.9% vs 8.3%; P ≥ .999; OR, 1.07; 95% CI, 0.21-5.40) did not differ significantly between cases and controls. The prevalence and odds of lateral meniscus tears (53.3% vs 43%; P = .34; OR, 1.85; 95% CI, 0.76-4.52), medial meniscus tears (31.3% vs 33.5%; P = .85; OR, 0.90; 95% CI, 0.37-2.21), and chondral lesions (16% vs 10.8%; P = .50; OR, 0.70; 95% CI, 0.15-3.21) also did not significantly differ between cases and controls. CONCLUSION: ACL-MCL injuries were most often due to a contact mechanism, whereas ACL tears without associated MCL injury were more frequently due to a noncontact mechanism. However, there were no significant differences in concomitant injuries in ACL-MCL knees versus ACL knees.