Acute thrombotic thrombocytopenic purpura following orthopedic surgery.

Release of unusually large von Willibrand factor (UL vWF) multimers and a deficiency of vWF metalloprotease may result in thrombotic thrombocytopenic purpura (TTP), a life threatening disease. Surgery has been associated with TTP, probably by releasing massive amounts of UL vWF. An association between TTP and orthopedic surgery has never been reported in the literature. We report a case of TTP following a total knee replacement surgery in which prior use of ticlopidine might have played a role.