BackgroundIntramedullary nailing with and without reaming leads to a reduction in cortical bone blood flow. The repair of the devascularized bone is mediated principally by the surrounding soft-tissue envelope. The objective of this study was to determine the effect on muscle blood flow of reamed and unreamed intramedullary nailing techniques.MethodsMidshaft tibial osteotomies to create a 2.5-cm segment of devascularized 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 tightly fitting (n = 5) locked nail. In the reamed group, limited reaming (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.ResultsOverall muscle perfusion was greater in the reamed group than in the unreamed group at the conclusion of the nailing procedure (p = 0.0001) and at 5 weeks (p = 0.0008) and 11 weeks after nailing (p = 0.001). The degree of canal fit of the intramedullary nails and the extent of reaming before nail insertion did not further influence muscle circulation.ConclusionThe results of this study demonstrate that in the presence of an intact soft-tissue envelope, intramedullary reaming of the canine tibia has a major effect on increasing the circulation to the surrounding muscles. The increased extraosseous circulation may have implications for fracture healing.