Thermo-mechanical stresses distribution on bone drilling: Numerical and experimental procedures

Abstract

In bone drilling, the temperature and the level of stresses at the bone tissue are function of the drilling parameters. If certain thresholds are exceeded, irreversible damages may occur on the bone tissue. One of the main challenges in the drilling process is to control the associated parameters and even more important, to avoid the surrounding tissue damage. In this study, a dynamic numerical model is developed to determine the thermo-mechanical stresses generated during the bone drilling, using the finite element method. The numerical model incorporates the geometric and dynamic characteristics involved in the drilling processes, as well the developed temperature inside the material. The numerical analysis has been validated by experimental tests using polyurethane foam materials with similar mechanical properties to the human bone. Results suggest that a drill bit with lower drill speed and higher feed rate can reduce the strains and stresses in bone during the drilling process. The proposed numerical model reflected adequately the experimental results and could be useful in determination of optimal drilling conditions that minimise the bone injuries.

Dynamic Numerical Simulation of Different Drill Bit Diameter on the Polyurethane Foams Drilling

“…During the tests, the solid rigid polyurethane foam material was at room temperature and remains equal at the distance where the strain gauges were installed (Fernandes, Fonseca, & Natal, 2017). An order 2 polynomial trendline illustrate the relationship between the drill bit diameter and the maximum stress obtained in the polyurethane foam material.…”

“…To define the material model of the solid rigid polyurethane foam should be taken in consideration the strain-rate with dependency of the material plastic curve. Strain rate is accounted for using the Cowper-Symonds model which scales the yield stress by the strain rate dependent factor as shown in equation 1, , (Fernandes, Fonseca, & Natal, 2017). This material model is an elastic-plastic with strain rate dependency and failure, which includes isotropic and kinematic hardening plasticity.…”

“…The mechanical properties used in all numerical models are summarized in table 3.1, , (Fernandes, Fonseca, & Natal, 2017). Cowper-Symonds parameter P 7…”

“…Conventional machining in drilling process of different materials use a controlled drilling parameters. In case of human bone surgeries, the surgeon controls manually the drilling parameters, such as the feed-rate due the imposed load control by hand (Fernandes, Fonseca, & Natal, 2017), . The orthopaedic surgery, neurosurgery, bone implant and repair operations are a few examples that involve these procedures, (Li, Abdel-Wahab, Demirci & Silberschmidt, 2014).…”

THERMAL ANALYSIS IN DRILLING OF EX VIVO BOVINE BONES

“…Based on temperature measurements, several studies have been carried out to assess various parameters that influence surgical drilling into bone. 1,12,13,[32][33][34][35][36][37][38][39] However, the complexity of the process and the extensive number of variables involved complicates the statement of concluding remarks. Experimental models coupled to other methodologies, such as computational models, has been a common practice in this type of analysis.…”