The faux profil (oblique view) of the hip in the standing position. Contribution to the evaluation of osteoarthritis of the adult hip

OBJECTIVE: The technique and results of a special oblique radiograph of the hip called the "faux profil" (FP) of the hip are described. The FP was evaluated for the detection of joint space narrowing in incipient osteoarthritis of the hip (OAH) as compared with the anteroposterior (AP) radiograph. METHODS: 58 hips with incipient osteoarthritis (joint space narrowing, 0-25% on the AP view) in 48 patients were identified among 200 consecutive patients fulfilling American College of Rheumatology criteria for OAH. Joint space narrowing was measured on the AP and FP radiographs of these 58 hips. RESULTS: The FP view provides a true lateral projection of the femoral head and neck, and an oblique view of the acetabulum tangential to its superoanteromedial edge. On this view, the width of the anterosuperior and posteroinferior parts of the joint space can be measured and compared. Among the 58 hips with incipient OAH, 36 (62%) showed joint space narrowing on the AP view and 51 (91%) on the FP view. Among the 22 hips without joint space narrowing on the AP radiograph, 16 (72.7%) showed joint space narrowing on the FP view, involving the anterosuperior part of the joint in 11 cases and the posteroinferior part in five cases. CONCLUSION: The FP view in the standing position should be used in incipient OAH as a complement to the AP view in patients with suspected OAH but no joint space narrowing on the AP radiograph. In this situation, nearly three quarters of hips in the study had joint space narrowing on the FP view, usually in the anterosuperior part and less often in the posteroinferior part of the joint.