Magnetic resonance arthrography of labral disorders in hips with dysplasia and impingement.

Despite the fact that classic studies on osteoarthritis of the hip have shown the periphery of the hip to be prone to degeneration, it was not until recently that an abnormal acetabular labrum has been associated with osteoarthritis. This study was designed to determine whether magnetic resonance arthrography can show differences in disorders of the labrum (tears, size, ganglion formation) expected in symptomatic patients with developmental dysplasia of the hip and anterior femoroacetabular impingement. Fourteen patients in each group were evaluated preoperatively not only clinically but also with conventional radiographs and magnetic resonance arthrographs. In both conditions, disorders of the labrum localized identically with a predilection to the anterosuperior quadrant of the acetabulum. Labral tears were observed in nine hips of each group. The labrum was enlarged in 12 hips with dysplasia but in none of the hips with impingement. Ganglion formation in the periacetabular area was seen in 10 hips with dysplasia and three hips with impingement. These findings provide evidence that the anterosuperior acetabulum represents the initial fatiguing site of the hip under both conditions. Based on these data, the size of the labrum and the presence of soft tissue ganglia seem to be good predictors for the presence of developmental dysplasia, whereas the presence of tears did not differentiate between conditions. The capability of magnetic resonance arthrography to show these differences in labral disorders suggests this method is a helpful diagnostic tool that can aid in defining the most appropriate treatment strategy.