MAGNETIC-RESONANCE-IMAGING STUDY OF ACETABULAR MORPHOLOGY IN DEVELOPMENTAL DYSPLASIA OF THE HIP

Acetabular morphology in developmental dysplasia of the hip (DDH) can be delineated by magnetic resonance imaging (MRI) more accurately than by previously available imaging methods. We describe the acetabular m orphology observed in 16 girls and one boy aged <3 years with untreate d DDH. The bony pathology was iliac bone widening with lateral drift o f the superior and posterior portions of the acetabular floor (extrusi o acetabulae), loss of sphericity, and diminished aperture of the acet abulum. The cartilage changes were a distortion and overgrowth of the acetabular cartilage, including labrum, and a convex appearance of the posterior portion of the acetabular cartilage.