Ashby, Elizabeth; Baker, Markus; Eastwood, Deborah M.
Background: The purpose of this study is to describe the natural history of hip morphology in patients with mucopolysaccharidoses (MPS) I and MPS II. Methodology: This is a retrospective radiographic analysis of 88 hips in 44 children with MPS I and II. Radiographs were examined to determine hip migration, femoral head sphericity, and acetabular dysplasia at different ages throughout childhood. In individual hips, change in morphology and rate of change were analyzed. Results: There was a high rate of hip migration and femoral head dysplasia in both MPS I and MPS II. Progressive migration was seen in three-quarters of hips and progressive femoral head deformity in over half of hips. Acetabular dysplasia was variable, ranging from normal to severely dysplastic, but did not change with time. Overall, hips were more dysplastic in MPS I than MPS II. Conclusions: Hip morphology is variable in MPS I and MPS II ranging from almost normal to severely dysplastic. Some hips do not deteriorate with time and thus surgical intervention may not be necessary in all cases. Deterioration is slow allowing time to plan a holistic approach to treatment.