title: Is magnetic resonance imaging necessary for normal plain radiography evaluation of contralateral non-traumatic asymptomatic femoral head in high osteonecrosis risk patient.
abstract: OBJECTIVE
  To examine the incidence rate and extension of non-traumatic asymptomatic osteonecrosis of the contralateral femoral head (ONFH) in high-risk patient groups.
  
  
  METHODS
  A cross-sectional design was used. We studied patients who visited at Orthopedics department, Khon Kaen hospital between January 2007 and December 2008. Only high-risk patients diagnosed with non-traumatic osteonecrosis in index side by plain radiography and asymptomatic contralateral sides with normal plain radiography evaluated for non-traumatic femoral head osteonecrosis were included in the analysis. We evaluated both hips of individual patient by MRI to determine the incidence, staging, and extension area of osteonecrosis.
  
  
  RESULTS
  Thirty-two patients with index femoral head osteonecrosis and non-traumatic asymptomatic contralateral femoral head were studied. Average age of these patients was 46.38 years. The most common risk factors were alcohol (78.12%) and corticosteroid use (18.75%). Osteonecrosis of the contralateral femoral head (ONFH) was found in 22 patients (68.75%). These hips were in stage VI (87.5%) with 99.05% extension area of osteonecrosis, large extension, C- location, and mix intensity of MRI on index side. We found stage I in all patients (100%), 80.62% extension area of osteonecrosis, large extension, C-location and mix intensity of MRI on ONFH at contralateral side with normal plain radiographic.
  
  
  CONCLUSIONS
  We found the high incidence rate and high extension area of asymptomatic osteonecrosis of the contralateral femoral head of the hip in high-risk patient. This result supported that silent aggressive disease can rapidly progress to advanced stage in a short time. Early detection of osteonecrosis in contralateral hip by MRI is considered a clinically necessary procedure in high-risk patients with unilateral hip osteonecrosis.
authors.affiliation: Department of Orthopaedics, Khon Kaen Hospital, Khon Kaen 40000, Thailand. piyakunmala@yahoo.com
authors.forename: Kriangsak
authors.initials: K
authors.lastname: Piyakunmala
authors.forename: Thananit
authors.initials: T
authors.lastname: Sangkomkamhang
authors.forename: Keerati
authors.initials: K
authors.lastname: Chareonchonvanitch
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D005270:Femur Head / Q000473:pathology*; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000601:surgery; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000379:methods