title: Bone scintigraphy as a prognostic indicator for bone collapse in the early phases of femoral head osteonecrosis.
abstract: OBJECTIVE
  Destructive and reconstructive processes at the reactive interface in femoral head osteonecrosis (FHO) are not well defined or predictable. The objectives of our study were to analyze scintigraphic characteristics of the reactive interface in the early stages of FHO and to assess the prognostic value of the reactive interface on scintigraphy (SC).
  
  
  METHODS
  Thirty-six hips in 27 patients (21 men, 6 women; mean age 41 years, range 20 64 years) with a final diagnosis of radiographic stage 1 (4 hips) or stage 2 FHO (32 hips) were evaluated by planar and pinhole SC. Tracer uptake at the reactive interface on pinhole SC was assessed visually. Three categories were formed: normal, moderately increased, and highly increased activities. The time to head collapse was observed.
  
  
  RESULTS
  Tracer uptake at the reactive interface was more frequently increased in hips with stage 2 of the disease than in those with stage 1. In hips with the same stage of the disease, different activities were detected [stage 1 FHO: moderately increased in 1 of 4 (25%) and highly increased in 1 of 4 (25%0) hips; stage 2 FHO: moderately increased in 8 of 32 hips (25%) and highly increased in 20 of 32 (631%/) hips]. Femoral heads with highly increased activity at the reactive interface collapsed more frequently and earlier: 13/15 conservatively treated hips in stage 2 collapsed in 1-6 months, whereas no hips with normal uptake at the reactive interface collapsed in 12 months follow-up and only one of six hips with moderately increased activity collapsed after 11.5 months (P < 0.05).
  
  
  CONCLUSIONS
  Our results indicate that the tracer uptake at the reactive interface can be different in the same stage of FHO. High tracer uptake at the reactive interface in the early phases of FHO seems to be a bad prognostic sign for femoral head collapse.
authors.affiliation: Department of Radiology, General Hospital Murska Sobota, U1. dr. Vrbnjaka 6, 9000 Murska Sobota, Slovenia. irena.sedonja@siol.net
authors.forename: Irena
authors.initials: I
authors.lastname: Sedonja
authors.forename: Vladimir
authors.initials: V
authors.lastname: Jevtic
authors.forename: Metka
authors.initials: M
authors.lastname: Milcinski
mesh_terms: D000328:Adult; D004164:Diphosphonates; D005260:Female; D005265:Femoral Neck Fractures / Q000000981:diagnostic imaging* / Q000209:etiology*; D005271:Femur Head Necrosis / Q000150:complications* / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D011379:Prognosis; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D004164:Diphosphonates; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C033905:technetium Tc 99m 1,1-diphosphonopropane-2,3-dicarboxylic acid