Effect of hyperbaric oxygen treatment on incorporation of an autogenous cancellous bone graft in a nonunion diaphyseal ulnar defect in cats

Objective-To determine whether hyperbaric oxygen treatment (HBOT) would aff ect incorporation of an autogenous cancellous bone graft in diaphyseal ulna r defects in cats, Animals-12 mature cats. Procedure-Bilateral nonunion diaphyseal ulnar defects were created in each cat. An autogenous cancellous bone graft was implanted in 1 ulnar defect in each car, with the contralateral ulnar defect serving as a nongrafted spec imen. Six cats were treated by use of hyperbaric oxygen at 2 atmospheres ab solute for 90 minutes once daily for 14 days, and 6 cars were not treated ( control group). Bone labeling was performed, using fluorochrome markers. Ca ts were euthanatized 5 weeks after implanting, and barium sulfate was infus ed to evaluate vascularization of grafts. Ulnas were evaluated by use of ra diography, microangiography, histologic examination, and histomorphometric examination. Results-Radiographic scares did not differ between treatment groups. Microa ngiographic appearance of grafted defects was similar between groups, with all having adequate vascularization. Differences were not observed between treated and nontreated groups in the overall histologic appearance of decal cified samples of tissue in grafted defects. Mean distance between fluoresc ent labels was significantly greater in cats given HBOT than in nontreated cats. Median percentage of bone formation in grafted defects was significan tly greater in cats given HBOT. Conclusions-Hyperbaric oxygen treatment increased the distance between fluo rescent labels and percentage of bone formation when incorporating autogeno us cancellous bone grafts in induced nonunion diaphyseal ulnar defects in c ats, but HBOT did not affect revascularization, radiographic appearance, or qualitative histologic appearance of the grafts.