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Cutting Edge Technology

24/07/2012


Research projects by Dr Peter Culmer and colleagues in the surgical technologies group at the University of Leeds include polymers for reversible adhesion to tissue and new laparoscopic tools to minimise tissue damage.

Surgery and technological innovation go hand in hand, a partnership that stems from the very foundations of surgical practice. This enduring partnership can be traced as far back as the Stone Age, when sharpened flint tools were used to perform craniotomies. The introduction of metal casting in the Bronze and Iron Ages enabled more reliable production of tools, perhaps providing some relief to the patients.

It is clear that the evolution of clinical need drives advances in technology used in the manufacture of surgical devices as well as in surgical systems themselves. In turn, developments in technology can enable new techniques and procedures that were previously unfeasible. The disposable endostapler1 was developed to enable procedures for laparoscopic bowel surgery (minimally invasive surgery conducted using long instruments within the abdominal cavity). Laparoscopy is increasingly popular and provides many benefits over open surgery, including reduced trauma and faster recovery times. The challenge of limited access significantly reduces the surgeon’s operative dexterity and can prevent critical tasks such as dividing and sealing the bowel when removing diseased tissue. The endostapler provides a single tool that overcomes this barrier safely and reliably, thus providing a step-change in surgical practice.

The harmonic scalpel2 is an example of technology offering a more incremental improvement to practice; the system uses ultrasonic vibration to simultaneously cut tissue and coagulate blood vessels. Combining these functions into a single device has helped to reduce blood loss and operative times in laparoscopic surgery. 

In this context of clinical drivers and technological advances, it is crucial that research into developing new and improved surgical technologies follows a multidisciplinary approach, where engineers and scientists work alongside clinicians to identify clinical need and ensure that new technology is appropriate for modern day surgery.

For example, the da Vinci surgical robot was initially targeted at routine procedures such as cholecystectomies and as a result struggled to justify its high price tag and technical complexity. However, surgeons recognised the potential benefits of the da Vinci system and its application has shifted towards the more complex procedures inherent in fields such as urology. Here, the advantages of the system are better exploited, providing the surgeon with more precise and dextrous operation than could be achieved with manually operated instruments. As a consequence, the cost–benefit ratio of the system is far more favourable. Therefore, in addition to adopting a multidisciplinary approach, it is important that academic researchers engage with the healthcare device industry, sharing expertise so that clinical need, utility and cost–benefit analyses are built into research and development practice.

The surgical technologies group at the University of Leeds is guided by these principles in the pursuit of engineering innovations to improve surgical practice. The group was formed by Professor Anne Neville (Mechanical Engineering) and Professor David Jayne (Surgical Sciences). Both areas are recognised as world-class research centres. Strengths in engineering include tribology (the study of friction, lubrication and wear) and bio-inspiration, and surgical sciences have pioneered influential multi-centre trials, for example, investigating the efficacy of robot assisted surgery for rectal cancer (the ROLARR study).

The group particularly focuses on modes of minimally invasive surgery that have become an increasingly preferred option to open surgery in many surgical specialities. But this transition is only part way along what many see as a spectrum moving from open surgery towards a concept known as Natural Orifice Transluminal Endoscopic Surgery (NOTES) in which access to the operating region is achieved without any external incisions by using natural orifices. The motivations for NOTES are reduced trauma and improved cosmesis, but the accompanying challenges (in terms of both technology and operating procedure) are huge. Consequently, intermediate approaches have been developed, principally Single Incision Laparoscopic Surgery (SILS), which aims to improve on conventional laparoscopic surgery by moving to a single access port for instrument access. In general, this move towards reduced trauma surgery has been clinically led, but the associated technology has not kept pace with this demand. Thus, there is a clear need for innovative multidisciplinary research into technologies that can enable and enhance these new, emerging modes of surgical practice, an area of priority for our group here at Leeds.

Polymers for reversible adhesion
A good illustration of this approach is the research the group is undertaking using biomimetic inspiration to develop polymers for reversible adhesion to tissue with a broad range of clinical applications. This work is inspired by the microstructed pads found on the feet of tree frogs. These consist of a hexagonal array of flat-topped epithelial cells approximately 10 µm in diameter, each having a finer sub-micron peg-like structure. The initial focus of this work is on the tissue of the peritoneum (the underside of the abdominal cavity). This has a mucous layer intended to prevent adhesion, which makes the task a considerable challenge. However, taking inspiration from the tree frog, adhesive forces are generated by capillary forces acting along discrete liquid bridges that form between the mucous and micro-scale pillars on the polymer surface (Figure 1). The outcome is promising, with the compound adhesive forces sufficient to support several grams per cm.3


Figure 1: A micro-scaled polymer surface designed to provide atraumatic adhesion to the peritoneum. Liquid bridges form between the pillars and the mucosal layer of the peritoneum generating adhesive forces

Ongoing research is using data from experimental studies to help develop adhesion models that can be used to optimise and adapt this approach for different tissue surfaces. This basic science research underpins translational work being undertaken within the group, including an intra-abdominal robot being developed to enhance imaging in laparoscopic surgery. The polymers provide the necessary adhesive forces to enable the device to walk on the underside of the insufflated peritoneum and at the same time avoid tissue damage. The long-term goal is a robot carrying a camera that can provide the surgeon with variable, controllable viewpoints during surgery without obstructing the operative region.

Laparoscopic tools to reduce tissue damage
There are numerous opportunities to improve current surgical instrumentation that have the potential to be rapidly translated into current practice. For example, the group is currently conducting research to study how human tissue is damaged when manipulated by surgical instruments, and crucially how this can be minimised. In laparoscopic surgery, organs and tissues are grasped with plier-like tools mounted on long shafts that pass through the abdominal wall. The mechanical arrangement, together with factors such as friction, make it extremely difficult for surgeons to perceive and regulate the forces that they apply to the tissue. This can result in tissue damage and cell death through excessive force being applied. The implications of this are significant with the possibility of slow recovery and increased complications through secondary infection.

To address this the group is conducting detailed investigations to understand how the magnitude, direction and duration of the applied force correlate with tissue damage. We have developed computer controlled laboratory apparatus that can grasp tissue specimens with repeatable and precisely controlled forces. We then measure and analyse the resultant macroscopic deformation using 3-D scanning technology and relate this to clinical measures of tissue damage using semi-quantitative histological analysis (Figure 2).



Figure 2: Characterisation of tissue damage caused by laparoscopic grasper tools. The macroscopic deformation is quantified using 3D scanning techniques (left) and correlated with histological analysis (right)

In the histological analysis, a high powered microscope was used to inspect thin slices of the tissue, stained using haematoxylin and eosin dyes, to reveal the architecture of the cells and those parts that have been deformed or destroyed. Those data are providing us with a detailed, quantitative understanding of tissue damage and how it can be reduced or prevented. We are exploiting this basic science research in partnership with Surgical Innovations (www.surginno.com) a manufacturer of laparoscopic instrumentation, to develop new laparoscopic tools that are optimised to minimise tissue damage. Several techniques are being employed, including the development of optimised tool surfaces and integrating mechatronic systems to automatically regulate applied force within appropriate limits. Collaborating with industry in this way helps to ensure that research, even at its most fundamental level, can be translated into commercial products and have real-world benefits.

Oncological engineering
To maintain a sustainable research base and to build on existing work, it is crucial to identify relevant new challenges and opportunities for innovation in surgery. It is therefore essential to cultivate environments and events that promote multidisciplinary interaction and facilitate the development of new ideas.

One important research challenge is finding new approaches to tackle cancer. Surgery remains the only curative intervention available with many forms of cancer. To address the challenges of improving surgical technologies in this field the University held a series of workshops, supported by the Engineering and Physical Sciences Research Council (www.epsrc.ac.uk), to bring together engineers, clinicians, scientists and industry representatives to develop the concept of "Oncological Engineering.” Initial research around this concept demonstrated that there is significant potential for advances in cancer surgery to mirror those already developed in radiotherapy and pharmacology.The preliminary workshops showed that there is great enthusiasm for this approach. To this end we established the Leeds Oncological Engineering conference to develop and explore this area, facilitate multidisciplinary collaboration and act as a catalyst for future research. The outcome surpassed our expectations. The conference included contributions from leading figures in academia and industry and forms a strong foundation for the follow-up event on 16–17 September 2012.

The growing area of applying technological innovations to help advance surgery has huge significance for healthcare providers, the patients that they treat and the medical device industry that manufactures and develops them. It is crucial to involve academia industry and healthcare providers to ensure that new technologies are clinically relevant and economically sound for commercialisation. The research being conducted by the University of Leeds’ surgical technologies group spans both fundamental science and applied engineering examples. This creative environment for surgical technologies research is symbolised by the Leeds Oncological Engineering conference, with its mix of scientists, clinicians, engineers and industrialists working together to find new surgical solutions to tackle cancer.

References
1. Early development of this device was pioneered by United States Surgical Corporation, now Covidien; it has also been developed by Ethicon Endo-Surgery.

2. This technology was introduced at similar times by Ethicon Endo-Surgery and Covidien.

3. R. Roshan et al., "Effect of Tribological Factors on Wet Adhesion of a Microstructured Surface to Peritoneal Tissue,” ActaBiomater, 7, 4007–4017 (2011).


Dr Peter Culmer is Senior Translational Research Fellow in Surgical Technologies, School of Mechanical Engineering, University of Leeds, Woodhouse Lane, 

Leeds 
LS2 9JT, UK  
Tel. +44 (0)113 343 214
e-mail: p.r.culmer@leeds.ac.uk
www.engineering.leeds.ac.uk/surgical-technologies



Dr Rob Hewson is Lecturer in the School of Mechanical Engineering, University of Leeds




Professor David Jayne is NIHR Research Professor, Academic Surgical Unit,
St James’s University Hospital, Leeds


 


Professor Anne Neville is RAEng Chair in Emerging Technologies, School of Mechanical Engineering, University of Leeds





   

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