Anticoagulant therapy for osteonecrosis associated with heritable hypofibrinolysis and thrombophilia.

Osteonecrosis develops as the end-result of reduced blood flow to the femoral head. We postulate that venous thrombosis leads to increased intraosseus venous pressure, reduced arterial flow and hypoxic bone death. Hypofibrinolysis (reduced ability to lyse thrombi) and thrombophilia (increased tendency to form thrombi) appear to play an important role in osteonecrosis. If coagulation disorders cause osteonecrosis, then anticoagulation might ameliorate osteonecrosis. In subjects with coagulation disorders and osteonecrosis of the hip, provided that anticoagulant therapy is started before irreversible segmental collapse of the head of the femur, osteonecrosis may be arrested or, speculatively, sometimes reversed. This has the potential of preventing femoral head collapse which usually leads to total hip replacement.