Bone-marrow transplantation in Hurler's syndrome. Effect on skeletal development.

Between 1980 and 1988, displacement bone-marrow transplantation was performed on 25 children with Hurler's syndrome (type-1 mucopolysaccharidosis). We describe the musculoskeletal development of 11 of the 12 surviving children and the orthopaedic procedures undertaken to treat progressive thoracolumbar kyphosis, hip subluxation and carpal tunnel syndrome. We found abnormal bone modelling, focal failures of ossification and an avascular disorder of the femoral head in every patient and offer an explanation for these phenomena. Increasing valgus deformity of the knees and progressive generalised myopathy caused loss of mobility as the children entered adolescence. The benefit of bone-marrow transplantation as a treatment for the skeletal disorders of Hurler's syndrome is limited by the poor penetration of the musculoskeletal tissues by the enzyme derived from the leucocytes.