Long-term direct oral anticoagulation in primary osteonecrosis with elevated plasminogen activation inhibitor

Osteonecrosis is a pathological condition that could lead to a debilitating physical disease and impede daily activities. It is generally categorised into aetiology - primary (idiopathic) or secondary. When direct damage to the bone vasculature or direct injury of the bone marrow is related to an identifiable cause such as traumatic injuries, steroid or bisphosphonate use, increased alcohol intake, sickle cell disease, autoimmune diseases, chemotherapy or malignancy, it is categorised as secondary osteonecrosis. On the other hand, osteonecrosis wherein the mechanisms of development are not fully understood is categorised as primary or idiopathic osteonecrosis. This category includes inherited thrombophilia and hypofibrinolysis as potential causes. There are no clear guidelines or general agreements about anticoagulation treatment and duration in primary osteonecrosis due to thrombophilia or hypofibrinolysis. We report a case of primary osteonecrosis associated with hypofibrinolysis and successful control with lifelong direct oral anticoagulation therapy.