Intermittent radiographic changes of rickets without defective trabecular bone mineralization in a case of spondylometaphyseal dysplasia.

Although a variety of metaphyseal and spondylometaphyseal dysplasias have been identified, the natural course of the skeletal defects in these disorders has not been well characterized. We describe an 8-year-old girl with spondylometaphyseal dysplasia, most closely resembling the Kozlowski type, in whom rachitic metaphyseal involvement underwent dramatic radiographic healing when she wore leg braces; discontinuation of the braces was followed by recurrence of the growth plate abnormalities. A generalized disturbance in mineral metabolism or skeletal remodeling to explain these radiographic changes was excluded by extensive biochemical studies and histologic examination of an undecalcified iliac crest specimen. Our observations suggest that the defect in endochondral bone formation in the spondylometaphyseal dysplasias may be responsive to mechanical factors and that interventions that alter stress and strain on the skeleton, such as immobilization or use of orthopedic braces, may considerably modify the radiographic appearance of the growth plate disturbance.