The effect of definitive continuous distraction employed with the Ilizarov type external fixation system on fracture healing: an experimental rabbit model

OBJECTIVES: The objective of this study was to evaluate the effect of definitive continuous distraction (DCD) employed through an Ilizarov type external fixator on fracture healing in a rabbit tibia model. METHODS: Fifteen mature New Zealand white rabbits weighing 2.8 to 4.0 kg were randomly assigned to three groups following osteotomy of the tibia and fibula. The first group (controls) was treated only with the Ilizarov type external fixator while the second and third groups were subjected to DCD amounting to 10% and 30% of the body weight, respectively, being employed through modulated springs on the Ilizarov external fixation system. All the rabbits were evaluated by radiographs on the 12th, 21st, 28th, and 35th days following surgery and were sacrificed on the 45th day. Radiographic evaluations were made according to the Lane and Sandhu's scoring system, and histologic evaluations according to the scoring system proposed by Heiple et al. The results were analyzed using the Kruskal-Wallis test. RESULTS: The highest radiographic and histologic scores were obtained from the second group, being 8.6 and 11.6, respectively (p<0.05). Radiographic and histologic scores of the third group were lower than those of the control group. CONCLUSION: Application of DCD of 10% of body weight through modulated springs on the Ilizarov external fixator improves fracture healing while a greater amount of instability results in delayed healing.