Predictive factors for acetabular labral lesions in osteoarthritis of the hip with radial magnetic resonance imaging--a cross-sectional study.

Objectives. To document the reliability of Abe's classification and to clarify the predictive factors for acetabular labral lesions in osteoarthritis of the hip with radial magnetic resonance (MR) imaging. Methods. Reliability trial for the classification of acetabular labral lesion was performed by six orthopedic surgeons, grading 20 radial MR images in a blinded fashion at an interval of 4-5 weeks. Radial MR images of 275 hips in 263 patients were prospectively analyzed to determine the relationship between acetabular labral lesions, their distribution, age, and the acetabular coverage. Results. Cohen's quadratic weighted kappa of inter-observer reliability was 0.784 for the grade and 0.812 for the shape category. The weighted kappa of intra-observer reliability was 0.852 for the grade and 0.90 for the shape category. Multiple regression analysis revealed that both the grade and the shape were associated with age, acetabular coverage, and location of the labrum. Conclusions. Abe's classification of labral lesions was reliable for both the grade and shape categories. Aging, acetabular dysplasia, and the anterosuperior portion would be predictive factors for degeneration of the acetabular labrum using radial MR imaging.