Traumatic trabecular lesions observed on MR imaging of the knee

Examinations carried out on 302 consecutive patients with MR of the knee between January 1988 and March 1989 were reviewed for detection of trabecular lesion. Twenty-seven patients found presenting trabecular lesion were further reviewed with specific reference to their activity level and need for specific therapy to determine the clinical significance of the trabecular lesion. Twenty-one of the trabecular lesions were in the femur, 5 were in the tibia, and one was in the fibula. Three of them were associated with a direct trauma, 12 with a valgus type injury, 3 with pure rotation mechanism, and 5 with a combination of valgus and rotation. In 17 cases trabecular lesion was a single finding, in 10 cases it was associated with some ligamentous tear. At the follow-up visit, 26 of the 27 patients with trabecular lesion had no symptoms, and the patient with moderate knee symptoms had had similar knee symptoms prior to the accident due to an osteochondral defect. We conclude that a trabecular lesion in an MR image is a benign bone change associated with knee trauma which heals without sequelae.