Histomorphometric comparison between continuous and discontinuous distraction osteogenesis

Introduction: Experimental research on optimising the distraction protocol has been performed extensively in the past. However, relatively little research has been done on the rhythm of distraction. Findings in the orthopaedic literature showed that the outcome of distraction osteogenesis (DO) is positively influenced by increasing the rhythm of distraction. The aim of this study is to quantitatively compare continuous with discontinuous rhythms of distraction in rabbits. Materials and methods: Tissue blocks of regenerated bone were harvested from thirty-eight young adult female New-Zealand White rabbits. After a latency period of three days, rabbits were subjected for eleven days to either single daily activation of the distractor at a rate of 0.9 mm/d, or triple daily activation at a rate of 0.9 mm/d, or continuous activation at a rate of 0.9 mm/d. After three weeks of consolidation, bone regenerates were analysed using histomorphometry. Results: The continuous DO group showed significantly (p < .01) more regenerate bone volume in the central part of the regenerate than the discontinuous DO groups. Higher osteoblastic activity was seen, as well as more blood vessels (p < .05). Bone volume and the number of blood vessels correlated significantly in the central part of the regenerate (p < .05). Also, the early mineral apposition rate (MAR) was higher than the late MAR (p < .05). Conclusions: Continuous DO significantly accelerates bone formation when compared with discontinuous DO.

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