Force prediction and analysis in surgical sawing of composite bone involving multi-tooth reciprocating and heterogeneous pore model

Bone sawing is an essential procedure in surgical operations. Understanding and control of cutting force are critical to improve operational quality. This study proposed a new finite element model (FEM) of sawing of bone to predict cutting forces. In this model, a randomly distributed gradient porous material model was newly developed instead of previous widely adopted homogenous bone models. Meanwhile, tooth deviation was first considered in the model to realistically simulate the heterogeneous composite bone feature and multi-tooth sawing process. An in vitro testing for bone sawing was carried out using a robot arm and a medical saw. The experimental results matched well with the predictions of FEM. The results showed the tangential and normal sawing forces were increased with the feeding speed, but reduced with the reciprocating speed because the cutting depth per edge was increased with the feed speed, but reduced with the reciprocating speed. In addition, mathematical models of sawing force and force ratio associated with sawing process parameters and tool ge-ometry properties were first proposed to facilitate evaluating the effects of process parameters on sawing forces. It was found that force ratio did not depend on reciprocating speed or feeding speed, but related to the rake angle and offset angle of saw tooth based on the theorical model. The theoretical models were also in good agreement with the experimental results. This study proposed efficient numerical and theorical methods together with experimental analysis for sawing force-related investigations. These force-processing-tool relations provide practical guidance of process selection and force control for high quality surgical sawing of bone.

Automated summary

Bone sawing is crucial in surgical operations. This study proposed a new finite element model to predict cutting forces, and it was validated by experimental results. The study also proposed mathematical models to evaluate the effects of process parameters on sawing forces. These findings provide practical guidance for high quality surgical sawing of bone.