High-Speed Cutting of Synthetic Trabecular Bone—A Combined Experimental–Computational Investigation

Macdarragh O’Neill,Ted J Vaughan

doi:10.3390/applmech2030037

Abstract

Orthopaedic surgical cutting instruments are required to generate sufficient forces to penetrate bone tissue while minimising the risk of thermal and mechanical damage to the surrounding environment. This study presents a combined experimental–computational approach to determine relationships between key cutting parameters and overall cutting performance of a polyurethane-based synthetic trabecular bone analogue under orthogonal cutting conditions. An experimental model of orthogonal cutting was developed, whereby an adaptable cutting tool fixture driven by a servo-hydraulic uniaxial test machine was used to carry out cutting tests on Sawbone® trabecular bone analogues. A computational model of the orthogonal cutting process was developed using Abaqus/Explicit, whereby an Isotropic Hardening Crushable Foam elastic-plastic model was used to capture the complex post-yield behaviour of the synthetic trabecular bone. It was found that lower tool rake angles resulted in the formation of larger discontinuous chips and higher cutting forces, while higher rake angles tended to lead to more continuous chip formation and lower cutting forces. The computational modelling framework provided captured features of both chip formation and axial cutting forces over a wide range of cutting parameters when compared with experimental observations. This experimentally based computational modelling framework for orthogonal cutting of trabecular bone analogues has the potential to be applied to more complex three-dimensional cutting processes in the future.

Highlights

Bone is a naturally occurring composite material whose constituent phases are hierarchically organised to provide a highly optimised structure that exhibits high stiffness and excellent resistance to fracture while being lightweight for efficient movement
It was found that lower tool rake angles resulted in the formation of larger discontinuous chips and higher cutting forces, while higher rake angles tended to lead to more continuous chip formation and lower cutting forces
The vast majority of these studies have focussed on cutting process in cortical bone, and to date, there is a distinct lack of studies examining the biomechanics of cutting in trabecular bone [11]

Summary

Introduction

Bone is a naturally occurring composite material whose constituent phases are hierarchically organised to provide a highly optimised structure that exhibits high stiffness and excellent resistance to fracture while being lightweight for efficient movement. The complex structural arrangement of bone gives rise to anisotropic, rate-dependent failure behaviour, which varies significantly depending on tissue composition and architecture [1,2,3]. This presents significant challenges in the development of surgical cutting instruments, which are required to generate sufficient forces to penetrate bone tissue while minimising the risk of thermo-mechanical damage to the surrounding tissue. The vast majority of these studies have focussed on cutting process in cortical bone, and to date, there is a distinct lack of studies examining the biomechanics of cutting in trabecular bone [11]

Methods

Results

Discussion

Conclusion