title: Quantitative and qualitative assessment of closed fracture healing using computed tomography and conventional radiography.
abstract: OBJECTIVE
  Development of new agents to induce fracture healing requires more sensitive methods to detect early changes in fracture repair. The aims of this study were to determine quantitative and qualitative features of fracture healing using volumetric computed tomography (CT) and to compare them with conventional radiography during the weeks following uncomplicated fractures of the appendicular skeleton.
  
  
  METHODS
  39 otherwise healthy men and women with acute, closed fractures of the distal radius, tibial and/or fibular malleoli, or tibial shaft, were enrolled and underwent CT and X-ray imaging at 1, 2, 4, 8, 12, and 16 (tibial shaft only) weeks post fracture. Qualitative assessment included fracture line/margins, fracture gap, external callus appearance, callus-to-cortex ratio, bridging, and radiologic union. Quantitative assessment of CT density changes (Hounsfield units [HU]) in the fracture gap was performed in a subset of 8 fracture patients using MEDx multimodality image analysis software (Sterling,VA). The analysis was performed by drawing free form regions of interest (ROI) covering the fracture gap on baseline (week 1) images and by automated registration of the follow-up images to the baseline co-ordinate system.
  
  
  RESULTS
  The mean time to achieve radiologic union on CT was slightly shorter than on X-rays for radial and tibial shaft fractures (7.3 vs. 8.0 weeks, P = .1). Blurring of the fracture margins and reactive sclerosis were the earliest signs of healing in both modalities. External callus formation was evident in 11 cases and was detected earlier with CT technique. Overall, CT images allowed for more complete and detailed visualization of healing compared with conventional X-rays, which were limited by cast and fixation hardware superimposition, especially in subjects with malleolar and distal radial fractures. Quantitative evaluation showed good intraobserver and interobserver reproducibility and a statistically significant correlation to qualitative changes.
  
  
  CONCLUSIONS
  Our methods of fracture healing assessment are reliable tools that are able to detect early changes in normal bone healing and may serve as useful additions to subjective image analysis in monitoring fracture healing in clinical trials. CT shows some advantages over conventional X-rays in evaluation of early fracture healing.
authors: Osteoporosis and Arthritis Research Group, Department of Radiology, 350 Parnassus Avenue, Suite 150, San Francisco, CA 94117, USA.
authors: Mikayel
authors: M
authors: Grigoryan
authors: John A
authors: JA
authors: Lynch
authors: Anke L
authors: AL
authors: Fierlinger
authors: Ali
authors: A
authors: Guermazi
authors: Bo
authors: B
authors: Fan
authors: David B
authors: DB
authors: MacLean
authors: Ainsley
authors: A
authors: MacLean
authors: Harry K
authors: HK
authors: Genant
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D017102:Fracture Healing / Q000502:physiology*; D005596:Fractures, Closed / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed