Acetabular labrum: abnormal findings at MR imaging in asymptomatic hips

PURPOSE: To determine the prevalence of abnormalities of the acetabular labrum in asymptomatic hips by means of magnetic resonance (MR) imaging and to correlate such abnormalities with age and the portion of the labrum. MATERIALS AND METHODS: MR imaging was performed in 71 asymptomatic hips that were radially sectioned perpendicular to the acetabular labrum at 30 degrees intervals. RESULTS: The shape of the labrum was triangular in 80% (304 of 382) of the labral segments, round in 13% (49 of 382), irregular in 7% (27 of 382), and not identified in 1% (two of 382). A homogeneous low signal intensity was observed in 56% (212 of 382). The frequencies of labral irregularity or its absence and of high signal intensity increased both with subject age and with a more anterior anatomic labral location. CONCLUSION: In asymptomatic hips, abnormal findings regarding the shape and signal intensity of the acetabular labrum can be detected by means of MR imaging. The fact that the findings vary according to age and labral portion should be considered in interpreting MR images in patients suspected of having a labral lesion.