CHRONIC PHYSEAL FRACTURES IN MYELODYSPLASIA - MAGNETIC-RESONANCE ANALYSIS, HISTOLOGIC DESCRIPTION, TREATMENT, AND OUTCOME

Thirteen myelodysplastic children with 19 chronic physeal fractures we re treated. All were treated with prolonged immobilization (average, 5 .8 months; range, 3-18 months) in either braces or casts; four of the fractures required operative futation to facilitate healing. All were healed at 4.8-years follow-up but, in four of the fractures, the growt h plate closed prematurely. Three of the children underwent magnetic r esonance imaging (MRI) of the injured physes, and one underwent physea l biopsy as part of her operative epiphysiodesis. Histologic analysis revealed three distinct zones of physeal pathoanatomy: a normal zone o f proliferation; a thickened, disorganized zone of hypertrophy; and a vascularized zone of fibrous tissue adjacent to the metaphysis. On MRT , there was thickening of the physis and irregularity of the zone of p rovisional calcification. The physeal cartilage and the juxtametaphyse al fibrovascular tissue enhanced with gadolinium. These findings corro borate earlier mechanistic proposals for physeal injury in myelodyspla sia: chronic stress or trauma to the poorly sensate limb produces micr omotion at the zone of hypertrophy, yielding a widened, disorganized p hysis, and leading to fracture, displacement, and delayed union.