An Increased Lateral Femoral Condyle Ratio Is an Important Risk Factor for a Medial Meniscus Ramp Lesion Including Red-Red Zone Tear.

PURPOSE

This study aimed to determine radiological findings associated with ramp lesions in knees with anterior cruciate ligament (ACL) injury.

METHODS

This study included the primary ACL reconstructions from June 2011 to March 2019. The exclusion criteria were combined fractures and multiligament injuries. Patients were categorized based on arthroscopy-confirmed presence of ramp lesions, which was defined as a longitudinal tear around the meniscocapsular junction or red-red zone tear of medial meniscus posterior horn. Binary logistic regression analysis was performed to find the risk factors such as age, sex, body mass index, medial tibial slope, mechanical axis angle, presence of Segond fracture, and lateral femoral condyle (LFC) ratio. Additionally, receiver operating characteristic (ROC) curves and area under the ROC curve (AUC) were evaluated.

RESULTS

Ramp lesions were identified in 89 (27.7%) patients among the total 321 included primary ACL reconstructions. The risk of ramp lesion was associated with increased LFC ratio (odds ratio [OR]: 62.929; 95% confidence interval [CI]: 8.473-467.351; P < .001), varus alignment >3° (OR: 5.858; 95% CI: 3.272-10.486; P < .001), and steeper medial tibial slope (OR: 1.183; 95% CI: 1.05-1.333; P = .006). The cutoff values of the LFC ratio and medial tibial slope for ramp lesions were >71% (AUC: 0.696; sensitivity: 43.82%; specificity: 91.38%; P < .001) and >12.1° (AUC: 0.643; sensitivity: 85.39%; specificity: 38.79%; P < .001), respectively.

CONCLUSION

Deep posterior LFC, varus alignment, and steep medial tibial slope were associated factors for ramp lesions in knees with ACL injury. In patients with ACL injury who show the above-mentioned radiographic findings, careful assessment and suspicion for ramp lesions should be considered.

STUDY DESIGN

Level III, retrospective cross-sectional study.