Hinge abduction hip dysplasia in (morquio a syndrome) treated by proximal femoral valgization osteotomy: a rare case report

Morquio A syndrome or mucopolysaccharidosis type IVA (MPS IVA) is an autosomal recessive and is a result of the abnormal metabolism of glycosaminoglycan, which manifests with normal intelligence, a cloudy cornea, dysfunction of endochondral ossification of epiphyseal cartilage, severe hip dysplasia, pain, impaired mobility, severe genuvalgum, thoracic kyphosis, and C1–C2 instability. An important manifestation is hinge abduction hip as an abnormal movement of the hip, which occurs when a deformed femoral head (often with a large uncovered anterolateral segment) impinges on the lateral lip of the acetabulum. Clinically appears as a restriction of movements, pain, and an unpleasant clunking sensation. CASE PRESENTATION: A 10-year-old girl suffering from MPS IVA with many signs of orthopedic manifestations. When concentrating on the hip joint, she had acetabulofemoral dysplasia and hinge abduction hip with the aid of plain radiographs and arthrography with dynamic testing. A valgization osteotomy of the proximal femur in combination with a shelf acetabuloplasty was performed bilaterally. CLINICAL DISCUSSION: There is no documented case of valgus osteotomy of the proximal femur in MPS IVA patients. Furthermore, preoperative arthrographies are not described as a routine diagnostic tool, because the routine surgical procedure was to do varus osteotomy with a high rate of failure. CONCLUSION: In our opinion, understanding of the dynamic function of the hip is essential for the surgical decision-making process. Our successful case with an 8-year follow-up illustrates that the well-known and widely performed valgus osteotomy in cases of hinge abduction in MPS IVA is an alternative, which should be considered preoperatively.