Arteriovenous malformation mimicking femoral osteolysis after total hip arthroplasty

We encountered a case of apparent progressive femoral osteolysis around a w ell-fixed cementless implant in a young patient. At the time of revision ar throplasty, massive hemorrhaging occurred during exposure and attempted fem oral component extraction. Urgent packing of the exposed endosteum with pol ymethyl methacrylate controlled the hone bleeding. Emergent angiography con firmed an arteriovenous malformation with extensive proximal diaphyseal inv olvement directly at the site of osteolysis. This arteriovenous malformatio n was treated successfully with selective arterial embolization and second- stage resection. In retrospect, the index arthroplasty operative note indic ated an excessive amount of blued loss, and prerevision radiographs showed osteolysis with uncharacteristic vascular markings. The presence of an oste olytic lesion in total hip arthroplasty should not bs assumed to be attribu ted to polyethylene granuloma, and any atypical radiographic features shoul d prompt further preoperative investigations.