Radiographic signs associated with femoroacetabular impingement occur with high prevalence at all ages in a hospital population

Abstract

Femoroacetabular impingement (FAI) is increasingly diagnosed clinically. Controversy exists about the significance of radiographic findings. Our goal is to determine the prevalence of radiographic FAI types and parameters in a hospital population clinically not suspected of having FAI. In addition we assessed whether pain, age and gender are associated with higher prevalences. Three hundred ten patients were included in this retrospective study. After applying the exclusion criteria, 262 patients (522 hips) remained. Two observers scored for radiographic parameters. A generalised estimation equation, Pearson's χ(2) test and logistic regression model were used. Radiographic signs of FAI were absent in only 58 hips (11.1 %). In the 40 hips (7.7 %) with cam impingement, males were more affected (P < 0.001). In the 330 hips (63.2 %) with pincer impingement, females were more often affected (P < 0.001). In the 82 hips (15.7 %) with signs of mixed type impingement, male hips were significantly (P < 0.001) more often affected. Age had some effect on the prevalence of coxa vara, acetabular index and acetabular retroversion. No correlation with pain was found. In this hospital population, signs occurred at a high rate. Radiographic parameters attributed to FAI are non-specific. Especially radiographic signs attributed to pincer type impingement have a high prevalence. • Femoroacetabular impingement is associated with an abnormal configuration of the hip joint. • The prevalence of femoroacetabular impingement parameters was high in our study population. • The diagnosis of femoroacetabular impingement should be made clinically.