Double-contrast CT arthrography of the cartilage of the patellofemoral joint.

For assessment of the value of computed tomography (CT) as a method for evaluating the cartilage of the patellofemoral joint, 100 knees were examined in 91 patients. With the patient in a supine position with the knee flexed at a 30 degree angle, a sufficient quantity of air and positive contrast material was required to obtain an accurate CT picture of the cartilage. Normal cartilage images of 53 knees and abnormal images of 47 knees were obtained by use of CT. The latter group was classified into eight types. When the CT findings of 70 knees were compared with arthroscopy and/or arthrotomy, the results showed that CT diagnosis was accurate in 68 of 70 knees, with a coincidence rate of 97.1%. Cartilage thickness at an arbitrary site and the extent of the ulcer within the deep layers were observed easily by CT. Although examination exclusively with arthroscopy had distinct disadvantages (e.g., the inability to assess either the specific thickness of the cartilage or the extent of the ulcers within deep layers), the combined use of arthroscopy with CT provided a precise three-dimensional image of the cartilage. CT was found to be a valuable noninvasive imaging method for patellofemoral joint cartilage evaluation.