Objective The purpose of the present paper is to compare the equivalence of the measurement of the alpha angle using the Ducroquet and cross-table lateral views. Methods We have recruited 90 patients, resulting in 95 hips. We have standardized the realization of the radiographic views. The incidence of the lateral cross-table views were taken with 15° of internal rotation with the patient in the supine position, and the incidence of the Ducroquet views was standardized with the patient in the supine position, with 90° of flexion and 45° of abduction of the hip. The alpha angle was measured in both lateral views, by two musculoskeletal radiologists. The measurements were performed in 2 different times: an initial evaluation and another 4 weeks afterwards. The t Student test was used and calculated the intraclass correlation coefficient (ICC). Results We have found a good intraobserver correlation for both views in different times; there was no statistically significant difference between the measurements performed by the two views. However, the interobserver correlation was low. Conclusion In conclusion, the Ducroquet profile view is a good choice for the α angle measurement and can be used instead of the cross-table view.
Keywords: femoracetabular impingement; hip/abnormalities; hip/diagnostic imaging; radiography.