Bone Contusion and Associated Meniscal and Medial Collateral Ligament Injury in Patients with Anterior Cruciate Ligament Rupture

BACKGROUND: The present study examined the prevalence of bone contusions in patients with anterior cruciate ligament (ACL) injury as well as its association with tears of the lateral meniscus, medial meniscus, and medial collateral ligament (MCL). METHODS: Eighty-one patients with an arthroscopy-proven ACL rupture for whom magnetic resonance images (MRI) were acquired within six weeks after the initial trauma were examined. The bone contusions on the lateral femoral condyle, lateral aspect of the tibial plateau, medial femoral condyle, and medial aspect of the tibial plateau were documented. The injury to MCL was also observed with MRI. The tears of the lateral meniscus and medial meniscus were detected during arthroscopy. The prevalence of lateral meniscus, medial meniscus, and MCL injuries was compared with the existence of the bone contusions. RESULTS: Sixty-eight (84%) of the eighty-one knees had bone contusions on magnetic resonance imaging. The prevalence of bone contusions was 68%, 73%, 24%, and 26% in the lateral femoral condyle, lateral aspect of the tibial plateau, medial femoral condyle, and medial aspect of the tibial plateau, respectively. There were two fractures of the posterolateral aspect of the tibial plateau and two fractures of the posteromedial aspect of the tibial plateau. The overall prevalences of injury to the lateral meniscus and medial meniscus were 54% (forty-four of eighty-one) and 51% (forty-one of eighty-one), respectively. The prevalence of MCL injuries was 22% (eighteen of eighty-one). The prevalences of lateral meniscus (p = 0.010), medial meniscus (p = 0.011), and MCL (p = 0.066) injuries increased as the bone contusion progressed from being absent, to involving only the lateral compartment, and finally to involving both lateral and medial compartments. CONCLUSIONS: Bone contusions were prevalent in patients with ACL ruptures, and injuries of the menisci and the MCL tended to increase with the progression of bone contusion. The contrecoup mechanism of bone contusion on the medial compartment resulting from an ACL injury was supported. These results suggest that a higher-energy injury led to a more extensive bone contusion and a greater prevalence of associated injury of other anatomic structures in the knee.