title: The prevalence of thrombophilia in idiopathic osteonecrosis of the hip.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  Patients with idiopathic osteonecrosis of the femoral head had a high prevalence of thrombophilia 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.
authors.affiliation: Department of Orthopaedics, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand. tanainit@hotmail.com
authors.forename: Thanainit
authors.initials: T
authors.lastname: Chotanaphuti
authors.forename: Danai
authors.initials: D
authors.lastname: Heebthamai
authors.forename: Montri
authors.initials: M
authors.lastname: Chuwong
authors.forename: Kris
authors.initials: K
authors.lastname: Kanchanaroek
mesh_terms: D000328:Adult; D000368:Aged; D000990:Antithrombin III / Q000032:analysis; D016022:Case-Control Studies; D005165:Factor V; D005169:Factor VIII / Q000032:analysis; D005260:Female; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D020151:Protein C Deficiency / Q000097:blood; D018455:Protein S Deficiency / Q000097:blood; D011859:Radiography; D012307:Risk Factors; D013785:Thailand / Q000453:epidemiology; D019851:Thrombophilia / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D055815:Young Adult
chemical_list: C095381:factor V Leiden; D000990:Antithrombin III; D005165:Factor V; D005169:Factor VIII