The Prevalence of Thrombophilia in Idiopathic Osteonecrosis of The Hip
Thanainit Chotanaphuti MD*, Danai Heebthamai MD*, Montri Chuwong MD*, Kris Kanchanaroek MD*
Affiliation : * Department of Orthopaedics, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand
Background : Thrombophilia is the propensity to develop thrombosis (blood clots) within the vein or artery
due to an abnormality in the system of coagulation. It is one of the pathophysiological causes of osteonecrosis
of femoral head (ONFH). Previous studies showed that the prevalence of thrombophilia was 1-15% in normal
population. There are two types of osteonecrosis of the femoral head, primary osteonecrosis (idiopathic
osteonecrosis) and secondary osteonecrosis from other known conditions. There is no previous report of the
prevalence of thrombophilia in idiopathic osteonecrosis of the femoral head in Thailand.
Objective : To study the prevalence of thrombophilia in Thai patients with idiopathic osteonecrosis of the
femoral head.
Material and Method: Fifty-five patients with osteonecrosis of femoral head were enrolled in this study. Forty
patients had idiopathic osteonecrosis and 15 patients had secondary osteonecrosis. The blood examination
of Factor V Leiden mutant, Factor VIII, Protein C, Protein S and Antithrombin III were completed in all
subjects.
Results : All patients with idiopathic ONFH had bilateral hip involvement. The prevalence of thrombophilia in
idiopathic ONFH was 32.5% (13/40). The protein C, protein S deficiencies, and increased factor VIII were the
common types of abnormal coagulation in idiopathic ONFH.
Conclusion : Patients with idiopathic osteonecrosis of the femoral head had a high prevalence of thrombo-
philia at about 32.5% in contrast to 1-15% in the normal population. The present study suggested that
thrombophilia maybe a risk factor of idiopathic osteonecrosis of the femoral head.
Keywords : Thrombophilia, Osteonecrosis of femoral head, Idiopathic osteonecrosis
