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 separate groups: (I) corticotomy; (II) osteotomy with multiple drill holes and an osteotome; (III) osteotomy with an oscillating saw. Distraction began on postoperative day seven and continued at a rate of 0.25 mm 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 were also performed after the dogs were killed. Periosteal callus formation was apparent in all groups at two weeks, and endosteal callus appeared in Groups I and II at three to four weeks. Perfusion studies at the end of the distraction period demonstrated vessels bridging across the regenerate gap in Groups I and II. Vessels bridging the gap were diminished in the oscillating-saw Group III specimens. During the distraction period, the appearance and length of the regenerate bone was similar for each group radiographically and by DEPX scanning. No histologic 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 simple transverse osteotomy yields regenerate bone that is indistinguishable from the technically more difficult corticotomy. Use of the oscillating saw may lead to delayed consolidation.