Effect of limited and standard reaming on cortical bone blood flow and early strength of union following segmental fracture.

Abstract

To quantitatively determine the extent to which limited and standard intramedullary reaming disrupts cortical circulation and to evaluate the effect on the biomechanical properties of the united fracture. Midshaft tibial osteotomies to create a 2.5-centimeter segment of diaphyseal bone were performed in ten adult dogs. Before insertion of a locked intramedullary nail, the tibia was reamed to either 7.0 millimeters (n = 5) or 9.0 millimeters (n = 5). Blood flow was measured using laser Doppler flowmetry during the nailing procedure and at eleven weeks postnailing. Bending stiffness and load to failure were determined for each healed tibia. Tibial blood flow was reduced for the limited and the standard ream groups by 63 percent (p = 0.002) and 83 percent (p = 0.0008), respectively. After canal reaming, perfusion was reduced to a greater extent in the standard ream group (p = 0.009). At eleven weeks postnailing, tibial perfusion increased to the same levels in both groups (p = 0.43) and returned to base-line values. Bending stiffness and load to failure were reduced after limited reaming (p = 0.002, p = 0.003) and standard reaming (p = 0.01, p = 0.002) were performed. Stiffness and load to failure were reduced to the same extent in both groups (p = 0.12, p = 0.25). Both limited reaming and standard reaming negatively affect diaphyseal cortical circulation. Limited reaming spares cortical perfusion compared with standard reaming at the time of nail insertion. No long-term advantage for limited reaming was demonstrated. Limited reaming may be advantageous acutely for the stabilization of tibial fractures in which the circulation is already compromised.