Muscle Perfusion after Intramedullary Nailing of the Canine Tibia

BACKGROUND: Intramedullary 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. METHODS: Midshaft 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 hind-limb using laser Doppler flowmetry. RESULTS: Overall 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. 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 effect on increasing the circulation to the surrounding muscles. The increased extraosseous circulation may have implications for fracture healing.