“Bone bruise” Detected with MR Imaging Associated with Anterior Cruciate Ligament Injury

Abstract

Magnetic resonance imaging (MRI) was performed on 38 patients with anterior cruciate ligament (ACL) injuries. According to the period from the last injury to evaluation with MRI, knees were divided into three groups. “Bone bruise” was detected in fourteen out of twenty-two (64%) knees in Group I (within three months) and one out of four (25%) knees in Group II (from three to six months). There was no bone bruise detected in twelve knees in Group III (over six months). A total of thirty-one lesions in the fifteen knees were detected as bone bruises. These lesions were most likely to be located in the middle third of the lateral femoral condyle and the posterior third of the lateral tibial plateau. Five out of fifteen knees with bone bruises were reevaluated with subsequent MRI. Reduction of the size and intensity of the lesions were documented in two knees reevaluated within three months from injury, and resoluation of the lesions was documented in knees reevaluated after four months. These findings suggest that bone bruises are associated with ACL injury and resolve within six months, but a precise pethoanatomic understanding of this MRI abnormal signal is not clear.