Progressive acetabular dysplasia in a boy with mucopolysaccharoidosis type IV A (Morquio syndrome): a case report

Morquio syndrome is an autosomal recessive lysosomal storage disorder, a mucopolysaccharidosis (PMS), characterized by abnormal metabolism of glycosaminoglycans. Major treatable concerns in patients with MPS type IV involve C1 to C2 instability, genu valgum, and hip subluxation. All patients demonstrate characteristic acetabular dysplasia and failure of ossification of the superolateral femoral head.

We report on a 6-year-old boy whose prime presentation was a waddling gait associated with pain since early childhood. Radiographic documentation showed progressive acetabulo-femoral dysplasia associated with additional skeletal deformities. Laboratory investigations showed increased urinary keratan sulfate and reduced leukocyte enzymatic activity of N-Acetyl-Galaktosamin-6-sulfate-sulfatase. Mucopolysaccharoidosis type IV A (Morquio syndrome) has been identified.

Patients with Morquio syndrome usually appear normal at birth but exhibit growth failure and spondyloepiphyseal dysplasia as infants. Most children are brought to a physician for investigation of what the parents perceive as an abnormal appearance by 12 to 18 months of age and thoracic kyphosis is supposed to be the first appearing deformity. In our present patient progressive acetabular dysplasia was the prime orthopaedic presentation causing effectively the development of a painful waddling gait.