The effect of intramedullary reaming on a diaphyseal bone defect of the tibia.

BACKGROUND The effect of intramedullary reaming on diaphyseal tibial defects has not been examined in the literature. The present aim was to relate the extent of reaming to angiogenesis and bone formation occurring around a critical-sized defect in the tibia for two scenarios, namely, when the bone defect is left empty and when the bone defect is treated with autograft. METHODS Eleven canines were allocated into two groups, namely, empty (n=5) or iliac crest autograft (n=6). All tibiae were reamed to 7.0 mm and fixed with a 6.5-mm statically locked intramedullary nail after creation of an 8.0-mm diaphyseal defect. The extent of reaming of the canal was dependent on the cross-sectional area of the tibia, because all tibiae were reamed to 7.0 mm. Fluorescent markers were administered at different times: calcein green (6 weeks), xylenol orange (9 weeks), and tetracycline (11 weeks and 14 weeks). Animals were sacrificed at 15 weeks and perfused with a barium compound. Analysis consisted of radiography, micro-computed tomography scan, and histology. RESULTS Linear regression analysis of percent bone volume and canal area provided a Pearson correlation coefficient of r=0.925 (p=0.025) for empty samples and r=0.244 (p=0.641) for autograft samples. Linear regression analysis of percent vasculature volume and canal area provided a Pearson correlation coefficient of r=0.784 (p=0.117) for empty samples and r=-0.146 (p=0.783) for autograft samples. Bone formation rates were reported as the distance between the fluorescent labels and were less within the endosteum, cortex, and periosteum, with extensive reaming in empty samples. CONCLUSIONS The results suggest that limited reaming may be beneficial to the acute management of tibial shaft fractures with a bone defect.