Radiologic Analysis of Osteochondritis Dissecans and Related Osteochondral Lesions

摘要

Localized defects in the articular cartilage and underlying subchondral bone are variously referred to as osteochondritis dissecans, osteochondral defects, or osteonecrosis of the articular surface. The radiologic hallmark of these lesions is separation of a bone fragment on the articular surface from the parent bone, usually with a visible lucent space intervening. These lesions are of uncertain etiology. A majority of patients with these lesions present in the second or third decade of life, are otherwise healthy, and are not unusually active athletically.1,2Most cases of talar dome lesions are likely posttraumatic.3–5Chronic, often unrecognized, mechanical stress may account for the majority of femoral condyle lesions.1,6,7Additional causes, including avascular necrosis, fat emboli, and even a familial dysplasia, also have been postulated, although thqv are not widely accepted.2,3It is certainly possible that each of these factors may contribute to the total spectrum of lesions which are lumped together under the term “osleochondritis dissecans.” To avoid confusion, it may be easiest to refer to all of these defects as osteochondral lesions or defects.After a lesion is identfied, the critical information for clinical management is whether or not the lesion is unstable. Unstable lesions often require surgical intervention to resolve the symptoms of pain and limitation of motion. Unstable lesions are those which do not have firm union to the native bone. Imaging of osteochondral lesions usually begins with plain film radiography. The need to determine expeditiously whether conservative or surgical therapy is most appropriate has led to the use of more sophisticated techniques, including nuclear medicine bone scintigraphy, tomography, arthrography, computed tomography (CT), combinations of arthrography with tomography or CT, and, most recently, magnetic resonance imaging (MR). The role of each of these modalities will be reviewed, with illustrative examples. It is hoped that this information will help readers in their own practices in identifying and systematically evaluating these lesions.