Femoroacetabular impingement: correlation between imaging parameters, sport activity, and chondral damage

BACKGROUND: Femoroacetabular impingement is characterised by an abnormal contact between the acetabulum and the femoral head-neck junction. Femoroacetabular impingement shows three main clinical frameworks: Pincer-FAI, Cam-FAI and Cam-Pincer mixed form. The aim of the study was to investigate the correlation between femoroacetabular impingement, imaging, activity and chondral damages.METHODS: Forty-one patients, undergoing arthroscopic chondroartroplasty for Cam and Cam-Pincer mixed form were considered. All patients underwent an X-ray hip evaluation (G1 group), while 15 patients also underwent a pelvis MRI evaluation (G2 subgroup). For G1 patients, the superior-inferior offset ratio and alpha angle were calculated from the X-ray examinations. For G2 patients, the antero-posterior offset ratio was also calculated from pelvis MRI. Chondral damage was classified according to the Outerbridge classification.RESULTS: The superior-inferior offset ratio and the antero-posterior offset ratio were respectively 0.50 ± 0.23 and 0.33 ± 0.19. The alpha angle predictive for a chondral damage of IV degree was 81.5°.The chondral damage of the patients suffering from Cam-FAI and Cam-Pincer mixed form were respectively 3.53±0.80 and 3.00±1.41.CONCLUSIONS: From the results was possible to: - Elaborate two tables providing a reliable indirect calculation of the alpha angle. - Establish an alpha angle cut-off value indicative for a IV degree chondral damage. - Show that Pincer-FAI does not represent an aggravating factor for chondral damage - Show that the level of sports activity was related to the severity of chondral damage. - Show that a physically demanding occupation was not an aggravating factor for chondral damage.