Role of Magnetic Resonance Imaging in assessment of osseous and cartilaginous coverage in developmental dysplasia of the hip

MRI assessment of acetabulum in DDH

Abstract

Background: Developmental dysplasia of the hip (DDH) can be diagnosed on X-ray by increased acetabular index, which is an indicator of the osseous acetabular coverage. Magnetic Resonance Imaging (MRI) has the advantage of visualization of the cartilaginous and soft tissue structures of the hip. This study aims to assess the role of MRI in assessment of the osseous and cartilaginous coverage of in dysplastic hips and to emphasize the principle of cartilaginous dysplasia of the hip.   

Methods: Consecutive series of 30 patients with DDH (40 dysplastic hips) were examined with radiographs and MRI. Radiographs with antero-posterior (AP) projection were used to measure the radiographic acetabular index (RAI). MRI was used to assess the osseous and the cartilaginous acetabular indices (OAI and CAI) at the coronal proton-density fat-suppressed sequence (PD-FS)

Results: Significant correlation was found between the radiographic and osseous acetabular indices as well as between the osseous and cartilaginous acetabular indices. No significant difference was found between the radiographic and osseous cartilaginous indices. The osseous acetabular index was significantly larger than the cartilaginous acetabular index.

Conclusion: Cartilaginous acetabulum is an important parameter that should be actively assessed in dysplastic hips. MRI is a valuable imaging modality that can efficiently assess both the bony and cartilaginous coverage of the dysplastic hips, a major advantage over
X-ray.