Increased lateral meniscal slope is associated with greater incidence of lateral bone contusions in noncontact ACL injury.

Purpose: (1) To investigate whether an increased lateral meniscal slope measured on magnetic resonance image (MRI) would be associated with greater risk of bone contusions in noncontact anterior cruciate ligament injury, and (2) to measure the relationship between the occurrence of bone contusions and associated findings observed in ACL deficient knees such as cartilage damage, anterolateral complex injury and concomitant meniscal tears.

Method: Patients who underwent ACL reconstruction surgery between 2013 and 2018 were retrospectively reviewed. Sixty-three patients were included in the study group (ACL + bone contusions group), 56 participants were in the control group (isolated ACL group). The presence and severity of bone contusions were determined from preoperative MRIs. The lateral meniscal slope and lateral posterior tibial slope were measured on the MRIs in a blinded fashion. The predictors of lateral bone contusions including age, sex, body mass index, lateral meniscal slope and lateral posterior tibial slope were examined by multivariable logistic regression. Associated findings including concomitant meniscal lesions, intra-articular cartilage damage and anterolateral complex injury, which were also calculated by multivariable logistic regression.

Results: The mean lateral meniscal slope in the study group was 6.5° ± 3.5°, which was significantly larger than that in the control group (3.8° ± 2.7°; P < 0.01). In addition, increased lateral meniscal slope was significantly associated with lateral bone contusions in noncontact ACL injury (Lateral femoral condyle (LFC): AOR 16.5; 95% CI 5.40-50.20; P < 0.01; Lateral tibial plateau (LTP): AOR 31.8; 95% CI 8.68-116.7; P < 0.01). However, lateral posterior tibial slope was not significantly associated with bone contusions. Moreover, the presence of lateral bone contusions was associated with concomitant lateral meniscal tears (OR 12.4; 95% CI 3.30-46.30) and cartilage damage (OR 2.9; 95% CI 1.04-8.18).

Conclusion: An increased lateral meniscal slope was associated with increased risk of lateral bone contusions in noncontact ACL injury. In addition, the presence of lateral bone contusions was associated with intra-articular cartilage damage, anterolateral complex injury and concomitant meniscal tears. Hence, additional information was provided for counseling patients who have increased LMS on the greater risk of knee rotational instability and identify patients undergoing ACL reconstruction who may benefit from extra-articular tenodesis.

Level Of Evidence: IV.