Elsevier

Medical Engineering & Physics

Volume 33, Issue 10, December 2011, Pages 1221-1227
Medical Engineering & Physics

Influence of orthopaedic drilling parameters on temperature and histopathology of bovine tibia: An in vitro study

https://doi.org/10.1016/j.medengphy.2011.05.013Get rights and content

Abstract

Orthopaedic drilling operations without optimum operating parameters by surgeons may cause bone defects such as bone fracture, cracks, osteolysis and tissue loss around the drilling zone. For the sake of optimum drilling parameters, an in vitro study was performed by considering the bone mineral density, bone sex, drill tip angle, drill speed, drill force and feed-rate. The specimens were taken from the drilled sites of fresh male and female calf tibias. The temperature changes at the drill site were investigated throughout the statistical and histopathological analysis. It was observed that the temperature increased with an increasing drill speed and decreased with high feed-rates and applied drill forces. The drilling temperatures of the female bovine tibias were found to be higher than that of the male tibias and the drill speed was found to be a significant parameter on the maximum temperature. Moreover, the maximum temperature increased with an increasing drill tip angle and bone mineral density. Therefore the bone quality around the drill site was found to be worse than the bone samples exposed to low temperatures.

Introduction

The heat generated from the metal–bone interface during bone processing in surgical operations has been a known phenomenon for years. The heat generated during drilling and sawing occurs due to the friction of the cutting tool to the work piece interface and transforming the applied cutting energy into heat energy that causes necrosis and combustion of bone tissue [1]. The common effective parameters include cutting speed, feed-rate, applied drill force, tool type and tool tip geometry. Using incorrect parameters may well cause bone tissue damages [2], [3], [4], [5]. Drilling operation during bone implantation and thermal damages were investigated [6], and it was observed that the drill force caused an increase in temperature. The effect of drill force, for several screw and pin fixations, was examined [7] and conventional orthopaedic drills were compared in respect to heat generation [8]. The thermal effects on bone tissue during orthopaedic sawing operations were also investigated [9], and the maximum temperature was found to be about 55 °C. It was reported that such temperatures will not damage the bone tissue during drilling in long bone joining operations [10]. On the contrary, the temperatures above 47–50 °C were indicated to cause thermal damage to the bone [11].

An osteosynthesis that specially formed cutting flutes screw tip, was developed to enable the insertion of the screw without drilling [12]. Chacon et al. [13] performed a study on the drill tip effect and heat generation when a drill was used several times. As in a similar study [14], the type of drill geometry effects were conducted on drilling performance, by investigating the different type of orthopaedic drill bits. Firoozbakhsh et al. [15] measured the heat generation using different blade thicknesses, with three different speeds. Such studies focused on the drilling and sawing operations and sometimes different types of operations had been performed for this purpose [16], [17]. However, some controversial, more compact studies are still needed in this area.

A new method for orthopaedic drilling, based on microwave energy localized at a hot spot, to penetrate bone tissues was developed [18]. Thermal deformation [19] on bone tissue with X-ray analyses and thermal profile description along the drilling edge were analysed by the finite element method, FEM [20], [21]. The surface temperature was measured by a thermograph method, using an analytical heat model [22]. By examining these studies, it would seem that the researchers generally focused on either one or just a few of the effective parameters, due to complexity of orthogonal heat mechanism [23]. In the above studies, the heat generation was cited for only one or a few of the heat parameters. The examinations evaluated were often with temperature measurements that were not combined with structural or histopathologic evaluations. In brief, there exists no in vitro study considering all the affected parameters in bone drilling operations. Some relevant studies also came up with different conclusions [24], [25].

In this study, a combined and multidisciplinary in vitro study has been executed by considering the effects of bone mineral density, bone sex, drill tip angle, drill speed, drill force and feed-rate on the maximum temperature during drilling of a tibial bone combined with histopathologic evaluation. It was shown from the in vitro experimental and statistical results that the drill tip angle and drill force have a statistically significant (p < 0.05) effect on bone temperature. The temperature of the drill zone has increased with the increasing angle of the drill tip. High temperatures were observed for the female bone samples and the temperature increased with the increasing bone mineral density.

Section snippets

Materials and methods

In surgical operations, to keep the deformation and bone necrosis to a minimum level, the optimum drill parameter in the operational zone is an extremely important matter. The level of thermal damage was determined by histopathologic examinations, in respect to a wide range of operational drilling parameters. In order to show the effect of heat generated during bone drilling, the bone temperature was measured by multi thermocouples which were mounted at the drill site, and the drilled part of

Results and discussion

The results obtained from the experiments were placed into two groups. In Group I, the temperature variation with drill parameters of bone mineral density, drill speed, force, bone sex and feed-rate are presented in box-plots (Fig. 2, Fig. 3, Fig. 4). In Group II the histopathology examination of the drill-operated bone were presented in histograms (Fig. 5, Fig. 6, Fig. 7, Fig. 8). To show the structural changes in the bone tissue, depending upon the temperature changes that occur during

Conclusion

The efficiency of drill parameters on temperature rise in the orthopaedic drilling processes was evaluated and histopathologic investigations have been executed. It was shown from the experimental and statistical analysis that the drill speed, force and bone mineral density were effective parameters on temperature rise, and so determined the bone quality at the drill site. The drilled bone quality was found to be better when the uncoated drills were used for bone drilling, compared to the

Conflict of interest statement

None declared.

Acknowledgement

Authors would like to thank to Prof. Dr. İ.H. Özercan and M. Sezer for the histopathology analysis.

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