Prevalence of Radiographic Signs of Femoroacetabular Impingement in Asymptomatic Patients and Non-Athletes

OBJECTIVE: Femoroacetabular impingement has been described as an anatomical variation of the proximal femur and/or acetabular rim, impinging the hip joint. A portion of the population asymptomatic in the hip may present radiographic changes from femoroacetabular impingement. The aim of the present study was to evaluate the prevalence of these signs in asymptomatic and sedentary males. METHODS: This was a clinical, observational, primary, cross-sectional, controlled study. A total of 32 male volunteers aged between 18 and 40 years, asymptomatic in the hip and sedentary, were selected from a university hospital orthopedic emergency room. All patients underwent standard anteroposterior pelvic radiographs. The measurements of the alpha angle, the retroversion index, the ischial spine signal, and the posterior wall sign were analyzed. RESULTS: The mean age was 29 years (18-40 years old). The prevalence of radiographic signs of femoroacetabular impingement using an alpha angle of 67 (o) was of 53.1%; with an alpha angle of 82 (o) , it was of 31.2%. The mean alpha angle was 67 (o) (52.4-88.2 (o) ), with 35.9% of the hips classified as borderline and 6.3% as pathological. The mean alpha angle for the right side was 67.5 (o) (52.5-88.2 (o) ), and, for the left, it was 66.6 (o) (53.1-86.9 (o) ). The mean retroversion index was 0.048 (right side: 0.044; left side: 0.052). The spine signal was positive in 15.6%, and the posterior wall sign, in 20.3% of the cases. CONCLUSION: This study showed that the prevalence of radiographic signs in a population of asymptomatic and sedentary adult men was high (31.2%). New studies are required to explian the actual clinical significance of this finding.