Comprehensive morphologic evaluation of the hip in patients with symptomatic labral tear.

A torn acetabular labrum is a well-documented source of hip pain, but the mechanism of injury is debated because the relationship between the bone morphology and labral tears is poorly understood. We compared hips with and without labral abnormalities to determine the relative incidence of morphologic abnormalities. The study group consisted of patients with a labral tear confirmed by arthroscopy or arthrotomy at the time of open débridement or periacetabular osteotomy. We compared the affected hip with the contralateral, unaffected hip to ascertain signs of hip dysplasia and impingement. We observed differences in the center edge angle, acetabular depth to width index, acetabular index of elevation, femoral head extrusion, lateral and superior subluxation, Sharp's angle, peak to edge distance, and acetabular retroversion. Similar differences occurred in the subgroup analyses. Symptomatic labral tears correlated with abnormal hip morphology as reflected by radiographic measurements of dysplasia and impingement. This relationship occurred in patients with hip dysplasia and patients without obvious femoral head uncovering. Our findings suggest abnormal hip morphology may be a risk factor for labral tears.