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.