title: Hyperbaric oxygen results in an increase in rabbit calvarial critical sized defects.
abstract: OBJECTIVE
  This study was undertaken to evaluate whether the effects of hyperbaric oxygen (HBO) therapy could alter the critical size for spontaneous healing of a bone defect in the rabbit calvarial model.
  
  
  METHODS
  An animal trial of 12 weeks duration was conducted using 20 New Zealand white rabbits, which were randomly divided into 2 groups of 10 animals each. Calvarial defects were created in the parietal bones of each animal bilaterally. Defects were critical-sized, 15 mm on one side and supra-critical-sized, 18 mm on the contralateral side. Group 1 received a 90-min HBO treatment sessions at 2.4 absolute atmospheric pressure (ATA) per day for 20 consecutive days. Group 2 served as a control without any HBO treatment sessions. Five animals in each group were sacrificed at 6 and 12 weeks. Data analysis included qualitative assessment of the calvarial specimens, post-sacrifice radiographs, as well as histomorphometric analysis to compute the amount of regenerated bone within the defects. ANOVA and paired sample t test were used for statistical analysis.
  
  
  RESULTS
  Both radiographic analysis and histomorphometric analysis demonstrated that HBO-treated animals had significantly more new bone within their defects compared with the control group (P < .001). There was no statistically significant difference between the percentage of new bone forming in the 15-mm and 18-mm HBO-treated defects. There was no difference between the 6-week and the 12-week HBO-treated groups. HBO is effective in enhancing the bony healing of full thickness critical sized as well as supra-critical-sized defects in the rabbit calvarial model.
  
  
  CONCLUSIONS
  Bone regeneration was significantly greater in the HBO-treated animals regardless of the defect size. HBO may have increased the diameter of the rabbit critical-sized calvarial defect to more than 18 mm.
authors.affiliation: University of Toronto, Toronto, Canada.
authors.forename: Ahmed M A
authors.initials: AM
authors.lastname: Jan
authors.forename: George K B
authors.initials: GK
authors.lastname: Sándor
authors.forename: Deborah
authors.initials: D
authors.lastname: Iera
authors.forename: Amir
authors.initials: A
authors.lastname: Mhawi
authors.forename: Sean
authors.initials: S
authors.lastname: Peel
authors.forename: A Wayne
authors.initials: AW
authors.lastname: Evans
authors.forename: Cameron M L
authors.initials: CM
authors.lastname: Clokie
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001861:Bone Regeneration; D006931:Hyperbaric Oxygenation; D008297:Male; D010294:Parietal Bone / Q000473:pathology / Q000601:surgery; D011817:Rabbits; D011897:Random Allocation; D014945:Wound Healing