MUSCLE PERFUSION AFTER INTRAMEDULLARY NAILING EF THE CANINE TIBIA

Background: Intramedullary nailing with and without reaming leads to a reduction in cortical bone blood flow, The repair of the devasculariz ed bone is mediated principally by the surrounding soft-tissue envelop e. The objective of this study was to determine the effect on muscle b lood flow of reamed and unreamed intramedullary nailing techniques. Me thods: Midshaft tibial osteotomies to create a 2.5-cm segment of devas cularized tibial cortex were performed in 19 adult canines, The tibia was stabilized with a locked intramedullary nail without reaming in 9 animals and with intramedullary reaming in 10 animals. In the unreamed group, the tibia was stabilized with a loosely fitting (n = 4) or a t ightly fitting (n = 5) locked nail. In the reamed group, limited reami ng (n = 5) or standard reaming (n = 5) was performed. Muscle perfusion was measured in the anterior compartment musculature of the hindlimb using laser Doppler flowmetry. Results: Overall muscle perfusion was g reater in the reamed group than in the unreamed group at the conclusio n of the nailing procedure (p = 0.0001) and at 5 weeks (p = 0.0008) an d 11 weeks after nailing (p = 0.001). The degree of canal fit of the i ntramedullary nails and the extent of reaming before nail insertion di d not further influence muscle circulation. Conclusion: The results of this study demonstrate that in the presence of an intact soft-tissue envelope, intramedullary reaming of the canine tibia has a major effec t on increasing the circulation to the surrounding muscles. The increa sed extraosseous circulation may have implications for fracture healin g.