DISTRACTION OSTEOGENESIS - A COMPARISON OF CORTICOTOMY TECHNIQUES

The left hindlimbs of 15 adult mongrel dogs were lengthened using the Ilizarov external fixator. Five dogs were assigned to each of three se parate groups: (I) corticotomy; (II) osteotomy with multiple drill hol es and an osteotome; (III) osteotomy with an oscillating saw. Distract ion began on postoperative day seven and continued at a rate of 0.25 m m every six hours for 26 days. The regenerate segments were evaluated with weekly radiographs and Dual Energy Photon X-ray (DEPX) beginning at day seven. Barium perfusion studies and histologic preparations wer e also performed after the dogs were killed. Periosteal callus formati on was apparent in all groups at two weeks, and endosteal callus appea red in Groups I and II at three to four weeks. Perfusion studies at th e end of the distraction period demonstrated vessels bridging across t he regenerate gap in Groups I and II. Vessels bridging the gap were di minished in the oscillating-saw Group III specimens. During the distra ction period, the appearance and length of the regenerate bone was sim ilar for each group radiographically and by DEPX scanning. No histolog ic differences were seen in Groups I and II. Three of the four tibias cut with the oscillating: saw did not consolidate at ten weeks. A simp le transverse osteotomy yields regenerate bone that is indistinguishab le from the technically more difficult corticotomy. Use of the oscilla ting saw may lead to delayed consolidation.