Effect of hyperbaric oxygenation treatment on lengthened callus

We examined the effect of hyperbaric oxygenation (HBO2) treatment on lengthened callus. The left tibias of 18 immature rabbits were progressively lengthened 14 mm by external fixator. They were divided into three groups of six each. The early HBO2 treatment group was exposed to HBO2 (3 atm abs, 2 h x day(-1)) once a day for the waiting period and the elongation period (17 days), the late HBO2 treatment group was exposed to HBO2 (same condition) for 17 days after the elongation period, and the control group received no HBO2 treatment. The radiographic examinations showed a tendency toward rapid callus formation in the early HBO2 treatment group. The percentage of bone mineral density evaluated using dual-energy x-ray absorptiometry in the early HBO2 group was significantly higher than that in the control group for 4 wk after the elongation period. These results suggest that HBO2 in the waiting and elongation periods enhances lengthened callus formation.