Magnetic resonance imaging in osteoarthrosis of the dysplastic hip.

We performed magnetic resonance imaging (MRI) in osteoarthrosis (OA) of 35 dysplastic hips in 28 patients using a 1.5-Tesla superconductive magnet. MR images were compared with conventional radiographs and arthrograms. MRI demonstrated cartilage irregularity and joint space narrowing in 17 hips earlier than did radiographs. Acetabular labrum tears were observed in 24 hips by MRI and in 23 hips by arthrography, suggesting that the former may be as useful as the latter. Osteophytes, joint effusion and synovial proliferation can be identified better by MRI than by conventional radiography. An MR grading system was established according to the thickness of the cartilage and sclerosis of the acetabulum or femoral head. This system can be a powerful tool to recognize the early stage of OA. MRI can demonstrate directly the severity of OA, including early degeneration of articular cartilage and acetabular labrum tear.