Effect of fracture fixation on cortical bone blood flow.

Because internal and external fixation devices alter blood flow, and thus the transport of nutrients to the cortical bone of a healing fracture, we studied the effects of a fluted intramedullary rod (IMR), a half-frame external fixator (EF), and a compression plate (PL) on the cortical bone directly adjacent to the fracture site at 4 and 48 h and 14 and 90 days after fixation. Three specific areas of cortical bone were studied: endosteal cortex, periosteal cortex, and subplate cortex (cortical bone under the compression plate). The fractures fixed with IMR had the lowest blood flow at all time periods studied. At 4 h, the difference between IMR and PL or EF was statistically significant in the endosteal cortex (p less than 0.01 or p less than 0.05, respectively); also, the difference between the IMR and EF in the subplate cortical bone region was significant (p less than 0.05). At 14 days, the blood flow to the endosteal cortex was still significantly lower with IMR than with EF (p less than 0.025). At 90 days, the blood flow to the subplate region of cortical bone was significantly (p less than 0.02) higher with PL than with IMR but there was no significant difference in bone remodeling with the different fixation devices.