Prevalence of Femoroacetabular Impingement in Younger Patients Undergoing Total Hip Arthroplasty

The pathogenesis of hip arthrosis is complex with many risk factors. Femoroacetabular impingement abnormalities are thought to be a factor. To determine the prevalence of femoroacetabular impingement in younger patients who had undergone hip arthroplasty, the authors reviewed preoperative radiographs to determine radiographic indices of femoroacetabular impingement in 142 patients (92 men and 50 women) younger than 50 years old and who had undergone hip replacement. The average age of the patients was 43.4 years. The center-edge angle (Wiberg), the alpha angle (No¨ tzli), and the sacrococcygeal–symphysis distance were measured. The range of a sacrococcygeal–symphysis distance in both men and women was used to identify retroverted acetabuli in properly centered radiographs. In this population, radiographic signs of cam-type femoroacetabular impingement were prevalent in patients younger than 50 years old who had undergone hip arthroplasty. Ninety-two (65%) patients had an abnormal alpha angle indicating cam impingement: 63 men (68%, alpha angle ½69°) and 29 women (58%, alpha angle ½51°). Sixteen patients (11%) had signs of a retroverted acetabulum, suggesting pincer impingement. Of these, 11 had an abnormal alpha angle. Sixteen patients had hip dysplasia; of these, 10 had an abnormal alpha angle. Patients presenting with hip pain, minimal osteoarthritic changes, and indices of femoroacetabular impingement may be suitable candidates for early operative intervention to decompress the impingement that may potentially retard or arrest the progression of arthrosis in these patients.. (Journal of Surgical Orthopaedic Advances 21(3):122–125, 2012)