Craniofacial bone an experimental study on craniofaicial disttaction osteogenesis

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Cranioplasty performed with distraction osteogenesis has gained much attention these days. It, however, still is controversial whether this novel method could supersede conventional method. To substantiate its usefulness and safety, we conducted an experimental study on calvarial distraction osteogenesis in rabbits.(STUDY ON OSTEOGENESIS) After decapitation, soft X-ray photograph was taken and the osteogenesis area was calculated using NIH image. The osteogenesis area was revealed to occupy 38%, 42%, and 62% of the bone defect area, 2weeks, 4weeks, and 8weeks after distraction, respectively. No osteogenesis area was demonstrated just after distraction. Following soft X-ray examination, the specimens were decalcified and serial 4-μm saggital sections were prepared. Histlogical examination using light microscope demonstrated woven bone and osteoblast at the distraction space 4weeks after distraction, suggesting intramembranous ossification. More advanced osteogenesis and the transition from woven bone to lamellar bone were demonstrated 8weeks after distraction. Chondroid was also developed, indicating so-called trans-chondroid bone formation. These findings led us to conclude that cranioplasty with distraction osteogenesis promote osteogenesis and reduce calvarial bone defect formation.(STUDY ON BRAIN DAMAGE) Histological examination using light microscope demonstarated that the dura mater had not been ruptured by distraction and was kept attached to the calvarial bone. There was no abscess formation or blood accumulation at the epidural space. Brain injury was not detected either. These findings suggested that ordinary calvarial distraction do no harm to the brain or the dura mater