Prevalence and development of orthopaedic symptoms in the dutch hurler patient population after haematopoietic stem cell transplantation.

Hurler syndrome (MPS-IH) is a rare autosomal recessive lysosomal storage disease. Besides a variety of other features, Hurler syndrome is characterized by a range of skeletal abnormalities known as dysostosis multiplex. Despite the successful effect of haematopoietic stem cell transplantation on the other features, dysostosis remains a disabling symptom of the disease. This study analyzed the status and development of the orthopaedic manifestations of 14 Dutch Hurler patients after stem cell transplantation.Data were obtained retrospectively by reviewing patients' charts, radiographs and MRIs. Existing methods to measure the deficiencies were modified to optimally address the dysostosis. These measurements were done by two of the authors independently. The odontoïd/body ratio, kyphotic angle, scoliotic angle and parameters for hip dysplasia and genu valgum were measured and plotted against age. The degree of progression was determined. The intraclass correlation coefficient (ICC) was calculated to determine the reliability of the measurements.All patients showed hypoplasia of the odontoïd, which significantly improved during growth. Kyphosis in the thoracolumbar area was present in 13 patients and proved to be progressive. Scoliosis was observed in eight patients. Hip dysplasia was present in all patients and showed no tendency of improvement. In all but one patient, knee valgus remained more than two standard deviations above normal.Dysostosis remains a major problem after haematopoietic stem cell transplantation in Hurler patients. Moreover, except for dens hypoplasia, it appears to be progressive and therefore surgical interventions may be necessary in the majority of these patients.