title: An MRI-based semiautomated volumetric quantification of hip osteonecrosis.
abstract: OBJECTIVE
  To objectively and precisely define the spatial distribution of osteonecrosis and to investigate the influence of various factors including etiology.
  
  
  METHODS
  A volumetric method is presented to describe the size and spatial distribution of necrotic lesions of the femoral head, using MRI scans. The technique is based on the definition of an equivalent sphere model for the femoral head.
  
  
  METHODS
  The gender, age, number of hips involved, disease duration, pain intensity, limping disability and etiology were correlated with the distribution of the pathologic bone. Seventy-nine patients with 122 hips affected by osteonecrosis were evaluated.
  
  
  RESULTS
  The lesion size ranged from 7% to 73% of the sphere equivalent. The lateral octants presented considerable variability, ranging from wide lateral lesions extending beyond the lip of the acetabulum, to narrow medial lesions, leaving a lateral supporting pillar of intact bone. Patients with sickle cell disease and steroid administration presented the largest lesions. The extent of the posterior superior medial octant involvement correlated with the symptom intensity, a younger age and male gender.
  
  
  CONCLUSIONS
  The methodology presented here has proven a reliable and straightforward imaging tool for precise assessment of necrotic lesions. It also enables us to target accurately the drilling and grafting procedures.
authors.affiliation: Department of Orthopaedics, School of Health Sciences, University of Thessalia, 22 Papakiriazi str., 41222 Larissa, Greece. kmalizos@otenet.gr
authors.forename: K N
authors.initials: KN
authors.lastname: Malizos
authors.forename: M S
authors.initials: MS
authors.lastname: Siafakas
authors.forename: D I
authors.initials: DI
authors.lastname: Fotiadis
authors.forename: T S
authors.initials: TS
authors.lastname: Karachalios
authors.forename: P N
authors.initials: PN
authors.lastname: Soucacos
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D005260:Female; D005271:Femur Head Necrosis / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D012737:Sex Factors; D013997:Time Factors