Prevalence of radiographic markers of femoroacetabular impingement in asymptomatic adults

Abstract

Objective: to determine the prevalence of radiographic signs of femoroacetabular impingement (FAI) in asymptomatic adults and correlate them with data from physical examinations.

Methods: We conducted a cross-sectional study with 82 asymptomatic volunteers, 164 hips, between 40 and 60 years of age, selected by convenience. They were submitted to anamnesis and clinical examination of the hip, anteroposterior (AP) pelvis radiographs with three incidences, Dunn 45° and Lequesne false profile of each hip, to measure the variables. We measured the alpha angle, anterior offset of the femoral neck, cervical diaphyseal angle, CE angle of Wiberg, acetabular index, Sharp angle, and the crossing, ischial spine and posterior wall signs.

Results: our sample consisted of 66% women, mean age of 50.4 years. The average alpha angle was 45.10°, SD=8.6. One quarter of the hips showed alpha angle greater than or equal to 50°; among men the prevalence was 34%, and among women, 11%. We found indicative radiographic signs of femoroacetabular impingement in 42.6% of hips, whether femoral or acetabular, and the increased alpha angle was related to the decrease in hip internal rotation (p<0.001).

Conclusion: the radiographic findings of femoroacetabular impingement in asymptomatic patients were frequent in the studied sample. The increase in alpha angle was associated with decreased internal rotation.