NUI Galway – UL Alliance First Annual ENGINEERING AND - ARAN ...

Experimental Analysis of the Thermal Effects of Surgical Bone Cutting
Dolan E. 1 , Casey C. 2 , McNamara L. 1
1 Department of Mechanical and Biomedical Engineering, NUI Galway, Ireland
2 Stryker Instruments, Carrigtwohill, Cork, Ireland
e.dolan4@nuigalway.ie
Abstract
Surgical procedures depend on cutting tools that can
provide surgeons with access to the organs, without
causing extensive harm to surrounding tissues and cells.
The need for continual innovation with these products is
required to minimise the healing time and thereby
enhance post-surgical patient outcome. We aim to
advance the understanding of thermal effects of surgical
cutting on cell and tissue integrity to optimise postoperative
bone repair. These studies will inform design of
next generation tools and improve patient outcome.
1. Introduction
Brain, orthopaedic implantation and spine surgery, rely on
innovative technology that provides the surgeons with
access to organs while minimising harm to surrounding
tissue and post-surgery healing times. Continual
development of these devices is required to enhance
patient outcome. However there is a lack of knowledge
regarding the effects of thermal elevations in surrounding
tissue and cells during surgical cutting, and how these
might affect the healing process. This thermal effect might
affect patient outcome by causing resorption of thermally
damaged bone leading to implant loosening and delayed
healing. Studies are required to characterize the
temperature generation local to surgical cut surfaces, and
also to develop an understanding of how these changes
effect cell and tissue regeneration.
2. Objectives
Investigate temperature elevation and distribution
during surgical cutting
Understand thermal responses occurring at cellular
and tissue level to elevated temperatures.
We use a combination of in vitro cutting on devitalized
and live bone tissue, and in vitro cell culture experiments
to address these objectives.
3. Methods
Heat Distribution: An infrared camera and
thermocouples were used to build profile of heat generated
during cutting for 0.5, 1, 1.5, 2 mins with sharp and blunt
surgical blade (Figure 1).
Figure 1:(a) Embedded thermocouple, (b)Thermograph
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Explanted bone: Cortical bone was cut from freshly
harvested ovine vertebrae. Samples were cultured for 2
weeks (αMEM, 10% FBS, 1% Penicillin-Streptomycin)
and heat treated at 60°C for 1 hour.
Cell culture: MLO-Y4s were exposed to heat shock for
various time/temperatures (47°C, 60°C for 0.5, 1, 1.5
minutes) and allowed to recover. Thermal
necrosis/apoptosis characteristics and actin filament
disruption was investigated using histological methods [1].
4. Results
Continuous cutting for 1 minute results in elevated
temperatures, Figure 2a, but do not exceed thermal
threshold of 47°C for 1 min [2]. Only 3% of the bone
tissue is exposed to >50°C for 15 seconds, Figure 2b.
Figure 2: (a) Temperature v. time (b) temperature v.
area of continuous cutting for 0.5, 1, 1.5, 2 mins.
Cells heat treated at 60°C for 1 min are less dense
showing characteristics of cell death (condensation of
the cytoskeleton and rounded cell morphology),
Figure 3b, compared to control of 37°C, Figure 3a.
Figure 3: MLO-Y4s at (a) 37°C, (b) 60°C for 1 min
5. Discussion
Continuous cutting remained below the thermal necrosis
threshold [2] for a cutting duration of 1min. Many surgical
cuts are quicker, the main tibial plateau as short as 20
secs. Our results show exposure to elevated temperatures
results in cell death, which is consistent with Li et al.[1]
who observed apoptosis/necrosis for exposure of 48°C for
10 mins and reversible responses for ≤45°C for 10 mins.
Further work is required to differentiate between apoptosis
and necrosis. These results have potential to inform the
design of next generation surgical tools and improve
patient outcome by optimising post-operative bone repair.
6. References
[1]. Li et al. J. Orthop. Res. 1999: 17: 891-899
[2]. Erikkson et al. Int. J. Oral Surg. 1982: 11: 115-121