Metaphyseal Bone Collapse Mimicking Slipped Capital Femoral Epiphysis in Severe Renal Osteodystrophy

Abstract

Slipped capital femoral epiphysis is a well-recognized skeletal complication of renal osteodystrophy in adolescence, which is distinct from idiopathic slipped capital femoral epiphysis in its etiology. We report a case of severe mixed-type renal osteodystrophy with metaphyseal bone collapse that mimicked slipped capital femoral epiphyses. Case history, laboratory and radiological evaluation, and bone biopsies are discussed. A 14-yr-old girl presented with left hip pain showing bilateral metaphyseal bone collapse accompanied with posterior-inferior displacement of capital femoral epiphyses after 2.5 yr of GH treatment. Blood chemistry, showing high levels of alkaline phosphatase and PTH, and a transiliac bone biopsy, indicating severe osteomalacia with osteitis fibrosa, along with serial computed tomography images of the hips from the presymptomatic stage, led to accurate diagnosis and successful treatment by administration of high-dose vitamin D. This case emphasizes the importance of controlling hyperparathyroidism well in children with chronic renal insufficiency, particularly at adolescence before initiating GH treatment. When children with renal insufficiency present with displacement of capital femoral epiphysis, it is necessary to evaluate the serum levels of alkaline phosphatase and PTH and metaphyseal bone quality below the physis.