Abstract
Bone cutting produces heat which macroscopically leads to charring and the formation of bone dust. As part of a project to design a novel bone-cutting device, we studied the extent of histological thermal damage from different cutting blades. Three blades were used: a nineteenth century bone hacksaw, and modern sagittal saw blades manufactured by Ortho Solutions and Stryker. Sheep femurs were harvested from recently euthanised animals and cuts were made with these blades. Specimens were immediately stored in formaldehyde, decalcified, and stained with hematoxylin and eosin. The edge of the specimens was then photographed microscopically, and the images examined with Axiovision software (Carl Zeiss AG, Oberkochen, Germany). Visual examination allowed identification of live and dead osteocytes, and also to measure their depth from the surface. A minimal of 7 images was obtained per blade. The hacksaw specimens had the highest percentage of live osteocytes (n=214, 59.8%), and the shortest average depth where live osteocytes were located (169 μm, SD 78.15). In comparison, the percentage of live osteocytes for the Ortho Solutions (n=156, 17.4%) and Stryker (n=168, 29.5%) blades were much lower. The difference in average depths where live osteocytes were located was statistically significant between the three groups (p<0.001). In conclusion the hacksaw appeared to produce the least thermal damage histologically during cutting. The results reflect a relationship between certain features in cutting blade designs and the extent of thermal damage. Future experiments to monitor heat produced during cutting are planned.
