Filling long bone defect-pseudoarthroses under combined osteosynthesis conditions (an experimental study)

Purpose. To reveal osteogenesis features for canine leg defect filling under combined (the Ilizarov fixator and an intramedullary locked pin) osteosynthesis. Materials and Methods. Five adult mongrel dogs used in the experiments. These dogs underwent modeling tibial defect-pseudoarthrosis. After that, intramedullary osteosynthesis performed with the pin locking in the proximal part, and the Ilizarov fixator applied with further osteotomy in the lower third. Results. The support function of the limb occurred by the middle of distraction and became more active after the fixator removal in all the experiments. By the middle of distraction, the regenerated bone acquired zonal structure by X-rays, and its osseous parts looked like homogenous shadows of mainly periosteal structures. The median zone of radiolucency accounted for 35-40 % of the regenerated bone area. By the moment of the fixator removal, the osseous parts of the regenerated bone presented as periosteal and endosteal structures, “growth plate” had well-defined boundaries and accounted for 15-20 % of the regenerated bone area. By 30 days after lengthening the regenerated bone lost zoning in most experiments, and formation of mechanically strong regenerated bone observed. Pseudoarthrosis consolidation noted by the same period as well. Conclusion. The combined use of osteosynthesis various technologies allowed us to reduce the duration of device fixation stage with the kept volume of filling bone tissue deficit under the conditions of disordered intraosseous blood supply and endosteal osteogenesis.