Is Magnetic Resonance Imaging Necessary for Normal Plain Radiography Evaluation of Contralateral Non-Traumatic Asymptomatic Femoral Head in High Osteonecrosis Risk Patient
Kriangsak Piyakunmala MD*, Thananit Sangkomkamhang MD*, Keerati Chareonchonvanitch MD**
Affiliation : * Department of Orthopaedics, Khon Kaen Hospital, Khon Kaen, Thailand ** Department of Orthopaedics, Siriraj Hospital, Mahidol University, Bangkok, Thailand
Objective : To examine the incidence rate and extension of non-traumatic asymptomatic osteonecrosis of the
contralateral femoral head (ONFH) in high-risk patient groups.
Material and Method: 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.
Conclusion : 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.
Keywords : Osteonecrosis of the femoral head, ONFH, Normal plain radiography of osteonecrosis of the femoral head, magnetic resonance imaging in osteonecrosis of the femoral head
