Premature fusion of the proximal humeral epiphyses in thalassemia.

Premature fusion of the proximal humeral epiphyses with varus deformity is a common and characteristic radiologic finding in thalassemia anemia. A review of 17 cases with bilateral and one case with unilateral involvement, coupled with known anatomic and mechanical factors, suggested an explanation for this phenomenon. Hypertrophied marrow will thin the trabeculae and cortex, perforate the cortex through normal fenestrations, and proliferate subperiosteally. Normal force vectors result in medial humeral compression and ultimately premature fusion.