Research Proposal: Investigation into the Use of Laser Tools in Orthopaedic Surgery

The desire for tighter manufacture tolerances have seen substantial progress in laser ablation
precision, most recently through shifts to femtosecond ultrashort pulse lasers. The reduction in
localised heating from such equipment has enabled greater precision and reduced microstructure
damage, by dispersing energy throughout the material in both thermal and electron diffusion (He et
al., 2015). Sub-micrometre precision has been observed in the ablation of metals, semiconductors,
crystals, glasses and ceramics, inspiring potential for their use in bone ablation (Wang et al., 2015).
The greatest risk from such surgical application is that of fracture through high thermal-induced
stresses in the brittle material; it is therefore imperative that this localised heating reduction carries
over to use in live bone tissue. The opportunities offered by orthopaedic laser surgery are common
with other operations; laser ablation enables precision, operative ease and cauterisation of damaged
vessels, consequently promising increased surgical capabilities and improved patient recovery.
This proposal describes numerous opportunities for studying this process and the potential
implementation of femtosecond laser ablation in orthopaedic surgery. The first gauge of suitability
would come through the modelling of heat generation at the bone surface, resultant from various
pulse durations: nano-, pico- and femtosecond. This primary investigation would offer clarity to the
effect of localised and overall heating on deformation and mechanical failure, from which a
relationship between pulse duration, power and mechanical integrity could be established.
Presuming a satisfactory simulation outcome, further investigations would provide correlation
between beam intensity and bone density, indicating the suitability of the method in a variety of
locations and patient conditions.
With heating analysed, the next computation would investigate appropriate cutting surfaces. Laser
surgery can be either direct, where the laser radiation directly processes the tissue; or indirect,
where radiation modified the tissue through heating a coated tip attached to the end of the optical
fibre, a heated scalpel (Bredikhin et al., 2016). Appropriate cutting surfaces would be compared,
through modelling, before laboratory investigations are conducted.
With modelling phases complete, laboratory testing would follow; primary investigations would test
the laser on biological tissues. With small tissue samples tested, investigations into larger dead
tissue would be conducted. For reliable testing, primary bone ablation would be assisted with saline
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flow throughout the material, replicating the thermal transport afforded by blood flow in living
tissue. With procedures iteratively modified and remodelled, as the test subject becomes closer to
living tissue, a final non-clinical test, with donations from the recently deceased, would be
conducted. If all testing phases are successful and ethical approval is acquired, there may be an
opportunity for the procedural testing to be finalised through clinical trial.