The Natural History of Bone Bruises - A Prospective Study of Magnetic Resonance Imaging- Detected Trabecular Microfractures in Patients with Isolated Medial Collateral Ligament Injuries

We conducted a prospective study to evaluate bone bruises, or trabecular microfractures, associated with isolated medial collateral ligament injuries. Magnetic resonance imaging was performed on 65 patients with isolated medial collateral ligament injuries determined by physical examination and imaging studies. Of these 65 patients, 29 (45%) had associated trabecular microfractures. Follow-up images were completed at various intervals on 24 of these 29 patients (83%). Complete resolution of these lesions was observed in all cases. This process appears to occur as a result of gradual diffusion over a period of 2 to 4 months. Bone bruises associated with medial collateral ligament injuries are approximately one-half as common as bone bruises associated with anterior cruciate ligament injuries. However, medial collateral ligament-associated trabecular microfractures may be a better natural history model because these injuries are treated nonoperatively.

Bone bruises are trabecular microfractures that result from traumatic injuries to bone, most commonly about the knee. This clinical entity has been well described in patients with associated ACL injuries.11,17 However, the natural history of bone bruises and the ultimate fate of these lesions remains largely unknown. In a preliminary study, we noted that bone bruises can also occur in conjunction with isolated medial collateral ligament (MCL) injuries.8 The presence of bone bruises associated with these injuries has also been reported by other authors.9, 16,17 However, no one has classified these lesions or provided follow-up magnetic resonance imaging (MRI) data on these patients. Because MCL injuries are treated nonoperatively, unlike
many ACL injuries, a detailed investigation of bone bruises associated with these collateral ligament injuries provides a better natural history model. We therefore undertook a prospective study of bone bruises in patients with isolated MCL injuries to 1) define the prevalence of bone bruises in patients with these injuries, 2) determine the natural history of these bone bruises, and 3) propose a classification scheme for bone bruises associated with MCL injuries.