Impatient for robots
Robots performing surgery is a reality. Their human counterparts, however, are holding back development.
Picture the scene - you are on the operating table waiting for a routine surgery. The anaesthesiologist, nurses and technicians are all there, but along with the surgeon you see a robot positioned by the table. Sound like science fiction? Well, at least in some areas of medicine it is a reality.
When robot-assisted surgery was first developed in the late 1980s, we might have expected that by now all operating theatres would be 'staffed' by not only humans but also robots. This is far from the case, with robots still performing relatively few, often specialist procedures.
The earliest medical robots were often modifications of industrial robots used in the automotive or manufacturing sectors. Not only were they very large and cumbersome, but generally autonomous with little or no surgeon involvement once the patient had been 'clamped' in position on the operating table. They were best suited to orthopaedic procedures such as knee or hip replacements, where the robot could accurately mill bone according to data gained pre-operatively.
Inevitably, there were questions surrounding patient safety and ethics, and indeed many manufacturers of industrial robots forbid their use in close proximity to humans.
These robots also had definite limitations when it came to soft-tissue surgery, where structures were free to move and real-time adjustments and surgeon input are necessary.
In the early 1900s, surgeons recognised the high risks associated with making large surgical incisions, and the pain and long recovery times it often caused. This led to the development of minimally invasive surgery (MIS) and laparoscopic procedures, still widely used in abdominal surgery.
Here, a series of three to five small incisions are made, surgical instruments and cameras inserted, and the abdomen inflated to increase space and visibility. It is very successful, but there are limitations due to the surgeons' restricted field of vision, poor tactile feedback, and the years of training required to successfully manipulate the instruments.
This has led to the development of specialist surgical robots, probably the most well-known and commercially successful being the da Vinci Surgical System, manufactured by Intuitive Surgical Inc, of Sunnyvale, California, USA.
In this master/slave robot, the human surgeon sits at a master console, while the arms of the robot translate the surgeon's movements to instruments within the patient.
Originally developed for heart surgery, it is gaining much wider recognition in the area of radical prostatectomy (prostate removal), an operation performed tens of thousands of times each year in the UK.
For the patient there are many advantages to having laparoscopic or ultimately robot-assisted surgery, versus the traditional 'open' procedure.
They generally experience less post-operative pain, require smaller incisions with less scarring, have a reduced need for blood transfusions, and ultimately a shorter hospital stay with faster return to daily activities.
There can be also advantages for the surgeon; less anaesthesia, less blood loss, improved field of view, less fatigue, and a smaller risk of infection. Where it is well used, results from robotic surgery are usually comparable with or even exceed the standard 'open' procedures.
High capital cost
So why has robotic surgery not lived up to much of its initial promise? One of the most obvious answers is cost and, with the market-leading da Vinci robot costing around £1m, it is easy to see why.
Add to this annual maintenance costs of £100,000, and a £1,500 per operation cost of disposables: this is definitely not a cheap replacement for a human surgeon.
There are currently only a small number of da Vinci robots in use in the UK, and only one in an NHS hospital. With demand on the modern-day NHS almost forcing them to focus on the number of patients treated rather than results, the use of robots may not be cost effective.
Certainly, immediately following robot implementation, hospitals may experience increased operating times and an undesirable reduction in 'throughput' of patients. This is of less importance in private institutions, where this extra time is easier to justify and the financial budgets significantly larger. Here, the use of robots and the quality they promise can even be seen as a marketing tool to draw patients in.
Ironically, another barrier to adoption may well be the surgeons themselves. It may be a case of simply protecting your job in a profession requiring many years of intensive training.
Unlike MIS using laparoscopic techniques, which often required even greater skill on the part of the surgeon than an 'open' procedure, robotic surgery can level the playing field.
A highly-skilled surgeon with many years of acquired experience could perform an operation to exactly the same standard as a mediocre or newly-trained surgeon.
There might even come a day when routine surgical procedures could be better performed with robot assistants than a human surgeon alone.
It is often the senior surgeons who advise the hospital administrators on purchasing decisions, and these can be the very people with the most resistance to the adoption of new technology.
It is often the technologically-able junior doctors who feel excited by these developments, and yet it will be many years before they carry authority or can influence decision making.
From a legal standpoint, there are still questions surrounding liability in the use of robots in surgery, not only for surgeons and hospitals, but also the robot manufacturers themselves.
Just who is responsible for any complications or sub-standard surgical outcomes if robots have essentially performed a procedure?
Indeed, the costs of defending litigation, and the 'down time' for other institutions with the same machines while suits were settled, contributed to the liquidation of a number of the pioneering medical robot companies.
There are also unanswered questions surrounding the safety of robot use in theatres (physical size, weight etc), and failsafe mechanisms in the case of power failure, hardware or software malfunction.
Currently, robots are not performing surgeries which could not be completed by a surgeon if necessary, but what of more elaborate or specialist procedures in the future?
Some ethical and safety questions remain, but it seems likely that the smaller and more 'hands-on' robots in development today should increase the confidence of surgeon and patient alike. Regardless of whether we look at robotic or conventional surgery, there is always the potential for errors or sub-standard outcomes.
However, in the limited studies which have taken place comparing robot to surgeon, the robot is generally able to outperform the surgeon alone.
In procedures such as radical prostatectomy where the use of the robot is already widely accepted, it has shown distinct advantages in terms of improved patient outcome, faster recovery, less pain, and quicker return to daily activities.
Another barrier to robot use is the limited tracking of quality in current surgical procedures. It is difficult to prove that the use of a robot can lead to better post-operative results if outcomes are not being tracked, or the necessary accuracy of the procedure is unknown. A case in point is the replacement of hip and knee joints, routinely performed in many hospitals around the country.
Currently, the failure rate of replacement knee and hip joints is very high, with as many as 10 per cent of operations being re-do surgeries. In the words of a prominent orthopaedic surgeon, “almost every failure is a technical one”. Premature degradation and ultimately failure of the replacement joint can be caused by sub-optimal positioning at the time of the original surgery. This would not be acceptable in industry, so why so when our own bodies are involved?
The number one determinant of outcome is accurate diagnosis. The latest developments in robotic navigation are being facilitated by improvements in medical imaging technology. It is now possible to gain precise and cost-effective spiral 3D computerised tomography (CT) scans in around ten seconds.
Not only does this enable more accurate pre-operative planning than plain X-rays alone, but also allows intra-operative tracking and direct comparison of post operative results. An excellent pre-operative plan, with robotic guidance and navigation during the operation itself, can help a surgeon to position the new joint in a biomechanically optimal alignment, thus reducing future wear and restoring perfect function.
In the UK, some of the most exciting developments in the use of specialised robots for minimally invasive, bone-conserving orthopaedic surgery have come from Brian Davies, professor of medical robotics in the Department of Mechanical Engineering at Imperial College, and Justin Cobb, professor of orthopaedic surgery at Imperial College.
Together, they formed the Acrobot Company Limited in 1999 (Active Constraint ROBOT), a spin-off from their academic work within the Mechatronics Department.
Last year they received £2.6m of funding from a syndicate of investors, and this has enabled them to begin clinical trials and commercialise their products.
According to Graeme Brookes, CEO of the company: “Acrobot Sculptor is being used in clinical evaluations currently and we anticipate that it will be fully commercially available in the UK early next year”.
The ultimate goal of the Acrobot Company is to provide speed, accuracy, and reproducibility to improve surgical outcomes and ultimately patient quality of life.
The company are developing a range of products to provide a complete surgical system. This begins with the Acrobot Modeller, which enables a radiographer to take a pre-operative CT scan and process the data to produce a 3D model of the patients' exact anatomy. The surgeon can import this into the Acrobot Planner software, and define the precise positioning and type of implant to be used.
Uniquely, it also allows the surgeon to visualise the two halves of a joint separately, and thus ensure optimal range of joint motion is preserved. The surgeon also knows precisely what size prosthesis will be needed, reducing the expense and inconvenience of sterilising several choices. Sterilisation costs are also reduced during the procedure itself, as only one disposable 'burr' needs to be used for the majority of procedures, rather than preparing several trays of instruments.
Finally, the operative plan can be loaded into the Acrobot Sculptor System, a hands-on, special-purpose robot designed specifically for procedures such as total and partial knee replacement, total hip replacement and hip resurfacing.
The concept of the active constraint patented technology ensures that the robot is unable to move on its own, but rather works with the surgeon by assisting or resisting his movements within the pre-defined area.
CT-based software is used to produce a pre-operative plan detailing safe, boundary and forbidden areas for bone removal, thus ensuring an extremely accurate fit of the prosthesis. Anatomical registration and navigation is provided by the Acrobot Navigator during the actual surgery.
The Sculptor can sense the surgeon's movement requests, and provides increasing levels of torque as the boundary is approached. The surgeon has continuous feedback on how close he is to the edge of the region, thus ensuring the removal of a precise amount of bone.
For many years it has been recognised that many patients simply do not need total knee replacement (TKR), as only the medial or lateral articular surfaces of the bone are worn.
Modern imaging techniques allow surgeons to correctly identify varus or valgus (bow legs/knock knees) deformity and replace only the diseased bearing surfaces, a procedure known as unicompartmental knee arthroplasty (UKA).
Advantages of UKA include better preservation of range of motion as fewer ligaments are damaged, a smaller scar, a reduced risk of complications, shorter hospital stay, and faster rehabilitation.
Unfortunately not all patients who would be suitable for this procedure are offered it, as it can be more costly, time consuming and surgically complex. It has been estimated that over 10 per cent of TKR patients would have been suitable candidates for the reduced procedure, but it is not being offered in all hospitals. One of the issues is that it require millimetre perfect placement of the new joint surfaces to ensure optimal tracking and wear characteristics - a job at which a robot should be more consistent than the human eye.
Orthopaedic surgeons have long known that the accuracy with which the replacement joint is aligned directly affects the quality of the outcome, but strangely they do not know exactly how accurate they have to be.
It is not difficult to see that if a person's poor biomechanics or structural alignment contributed to the degeneration of their native joint, it will likely effect its replacement if it is positioned the same. Equally, if the replacement joint is located incorrectly due to surgeon error, this will compromise the result.
In knee replacement surgery, it is thought that 2° of varus/valgus alignment in relation to the hip joint would be an excellent outcome, while over 6° will likely lead to future problems.
Even this is difficult to substantiate however, as the human body is surprisingly adaptable and, even with sub-optimal joint alignment, some patients will remain pain-free.
Striving for perfection
Surgeons are always striving for a good outcome for their patients, and anything which improves their chances of achieving a consistently high quality result will be welcomed.
The results of a study using the Acrobot system in a randomised, double-blind comparative clinical investigation in 2004 was published in the journal Bone Joint Surgery. Thirteen unicondylar knee replacements were carried out using the Acrobot system and 15 were performed conventionally.
This demonstrated that the Acrobot system consistently and accurately enables the positioning of a prosthetic implant according to a surgical plan. All 13 Acrobot cases were implanted within 2° of a desired orientation versus six out of 15 for the conventional cases.
Of course, it remains to be seen if this improvement in quality will effect long-term outcome or reduce the need for re-operation, but results like this can only contribute positively to the acceptance of robots in surgery.
Even outside of the orthopaedic field, a number of exciting medical procedures are either being developed or improved with the use of robot 'assistants'. Work is ongoing to improve force feedback to the surgeon and improve tactile 'feel' to more closely replicate what the surgeon normally experiences.
Incisionless surgery using in-vivo robots designed to function entirely within the patients' body are also being discussed, although to all but the staunchest believers the practicalities are a long way off.
That said, stunning procedures which would once have been considered science fiction are already possible.
Even the most sceptical cannot fail to be inspired by the use of a robot to embed deep brain stimulation electrodes with a millimetre-perfect degree of accuracy into the brain of a Parkinson's patient, thus stopping their tremor and restoring quality of life.
Alternatively, imagine being able to implant radioactive brachytherapy 'seeds' every 3mm in a grid pattern into a cancerous tumour, thus destroying malignant tissue while minimising damage to healthy surrounding cells. The use of robots to facilitate procedures such as these will further endorse their acceptance in such highly specialist surgery, and likely drive research into future applications.
However, in the majority of today's surgical procedures highly-skilled surgeons do not need replacing.
The robots true application may well come in operations which are not currently technologically possible, or where outcome can definitely be improved with their use.
The need to counteract rising healthcare costs, and the demands on today's overstretched health service, is definitely a consideration.
The revolution could also be driven by productivity and, with the government striving for pay-by-results, there will be clear benefits in faster hospital discharge, high accuracy, and day-case opportunities facilitated by robot use.
In the US, where the use of surgical robots has gained wider acceptance, it is the patients themselves who are driving its adoption. Indeed, one of the better known manufacturers now markets its products almost exclusively to the general public, not via surgeons or hospital administrators.
It is patient demand to go to centres where the robot is in use that has driven hospital purchasing decisions.
With improved patient choice in this country, how long will it be before we see people selecting their hospital based on the fact that it has a robot and a trained surgeon?
With the days of the informed and empowered patient, and the availability of information over the Internet on surgical options and hospital surgical success rates, it is only a matter of time.