The Prevalence of Dysplasia in Femoroacetabular Impingement

It is unknown how often femoro-acetabular impingement (FAI) and hip dysplasia co-exist and which is more important in the development of intra-articular lesions such as labral tears. This study identified the prevalence of dysplasia on standard radiographs in a group of 76 consecutive patients with symptomatic FAI. The centre-edge (CE) angle of Wiberg, the acetabular angle (AA) of Sharp, FAI type, offset ratio and posterior wall sign were identified. 63 patients, predominantly young adult males (mean age: 34.6 years; 10:4 male-to-female ratio), met our inclusion criteria. Most females (13:18) showed signs of dysplasia based on the AA. No association of dysplasia with FAI group, offset ratio or posterior wall sign was found. 47% of our patients with FAI also had radiographic evidence of dysplasia (3-15% definite and 9-30% borderline, depending on the angle utilised). Surgery for FAI should therefore take into account the presence of co-existing dysplasia. Conversely, surgery for dysplasia should take into consideration the co-existence of FAI. The prime cause of labral pathology in the presence of dysplasia may be co-existent FAI and the latter problem may demand priority, not the former.