MR-IMAGING OF THE ACETABULAR LABRUM - VARIATIONS IN 200 ASYMPTOMATIC HIPS

OBJECTIVE. The purpose of this study was to describe the MR appearance of the acetabular labrum in asymptomatic subjects and correlate the M R appearance with age and sex. MATERIALS AND METHODS. We evaluated hig h-resolution T1-weighted spin-echo coronal MR images of one hip in eac h of 200 asymptomatic individuals (84 men, 116 women; mean age, 44 yea rs old; range, 15-82 years old). The labral shapes (triangular, round, flat, or absent), the intralabral signal intensity changes, and the p ossible extension of the intralabral signal intensity changes to the l abral surface were assessed on two sections for each subject and corre lated with age and sex. RESULTS. Triangle was the dominant shape seen on MR imaging (66%). However, its frequency decreased significantly wi th age. Absence of labrum was the second most frequent pattern (14%) a nd increased significantly with age. Round and flat labra were found i n 11% and 9% of subjects, respectively, with no significant age correl ation. The frequency of homogeneous labra with low signal intensity de creased with age. Intralabral areas of high signal intensity communica ting with the free surface increased with age. CONCLUSION. The large v ariability of the MR appearance of the labrum in asymptomatic hips mus t be considered when interpreting MR examinations of patients in whom labral lesions are suspected.