Robotics in surgery

The prospect of robots in surgery fuels all sorts of bizarre images. Iain Mckay-Davies explains what they can do, and exciting prospects for the future

We inform Mr Jones in bed three that we're going to nibble away at his hyperplastic prostate with a transurethral robot. This only serves to conjure up horrific images of perpetually advancing Terminator 2 style cyborgs, who barely flinch at Arnie's pump action shotgun rounds as he smirks: "Hasta la vista, prostate."

Although most people associate the science fiction writer Isaac Asimov with robots, Czech author Karel Capek was actually the first to coin the term "robot" in his 1917 play Opilec. Chemical mixtures, stamped into human shapes for the purpose of serving mankind, rebelled against their subservience and proceeded to annihilate the human race. Since then, the definition of a robot most relevant to surgery is by Davies (see reading list below): "A powered computer controlled manipulator with artificial sensing that can be programmed to move and position tools to carry out a range of surgical tasks." Thus the robot's role is not to replace the surgeon but to enhance the surgeon's innate abilities while under close supervision. This should be reassuring to the public with regard to safety and standard of care, plus the surgeons and other healthcare professionals. Robots can even improve surgical outcomes. For example, robots used for the implantation of prostheses of the hip and knee can lead to a more stable insertion, shorter recovery time, and a proposed longer life for the implanted prosthesis.

Surgical robots can be classified into active or passive. A passive robot would be used to position a fixture appropriately and then be switched off, to be followed by the surgeon inserting his instruments. An example of this would be a robot to help position a device for guiding neurosurgical biopsy needles. By contrast, an active robot would actually move the tools. These include laparoscopic camera holders, telemanipulators, and robots used for burring out tissue, such as the Probot for prostatectomies and Robodoc for hip prostheses.

Beginnings

The first surgical robots were modified industrial ones used in the late 1980s for neurosurgery to hold instruments for stereotactic biopsies (Unimate Puma 560). IBM then produced an industrial robot to ream out the proximal femur of a dog for the femoral component of a prosthetic hip implant (Robodoc) resulting in greater prosthetic surface area in contact with bone. At the same time Imperial College in London devised a robot for transurethral resection of hyperplastic prostates (Probot), which was the first robot to be used on humans. This system, incorporating an ultrasound probe at its tip, permits a three dimensional model of the prostate to be constructed, allowing the surgeon to decide which parts to remove.

Overcoming the limitations of laparoscopic surgery

Current techniques using minimal access surgery, such as laparoscopy, have clear advantages for the patient but are not without problems. Rigid instruments limit the degrees of freedom because the axes of movement are set. A two dimensional viewing system results in the loss of depth perception. A suboptimal arrangement of the equipment can result in a loss of the eye-hand-target axis, and the camera view is not directly under the surgeon's control. Thus the surgeon's sensory input is decreased, as is his dexterity, and his environment is suboptimal.

The Da Vinci robot, however, overcomes the loss of dexterity, visual quality, and control that hampers minimal access surgery. The camera, under the surgeon's direct control, has two video chips arranged to give retinal disparity. The images are presented to the surgeon's console separately, one for each eye, and this restores stereopsis (three dimensional viewing). The surgeon puts velcro rings around his thumb and index finger, and the robot replicates the exact three dimensional movements of the fingers. The surgeon moves his or her fingers as if they were the jaws of the surgical instrument, thus the system is truly intuitive. The Endowrist tips of the instruments mimic the human wrist, restoring dexterity, increasing the degrees of freedom, reducing fatigue, and allowing more complex procedures to be performed. They also decrease the operating time and reduce the learning curve required for its use. Elimination of tremor occurs in real time, as does scaling of movements (the robot can be set to move 2 mm for every 1 cm that the surgeon moves). The ergonomic eye-hand-target axis that is often lost with minimal access surgery is re-established by the console, making the surgery easier to perform. It is like inserting 7 mm hands into a patient and performing complex surgical procedures.

Surgery in space

Not only does the da Vinci robot improve on existing techniques, but surgery can be performed remote from the patient. The da Vinci robot is a master-slave telemanipulator robot, and the Zeus robot is also one of this type. The surgeon sits at a console (the "master") that remotely controls a "slave"--a large machine with three arms, two for holding the 7 mm diameter laparoscopic instruments and the third for moving the endoscope (camera). Although originally conceived by the military, these machines have the potential to be used in situations where there is a hazardous environment--for example, in radiation or even in space--without subjecting healthcare staff to unnecessary risks or hazards.

Between Zeus and da Vinci, thousands of operations have now been performed worldwide. Robotic telesurgery is now a reality, performed with the surgeon in the United States and the patient in France. High speed linkups via telephone or satellite are required to reduce the delay of data transmission to less than 300 milliseconds, and an assistant surgeon still needs to be present with the patient in order to make the incisions and insert the robot arms.

Public fear

The public need to be made aware of the various aspects and applications of these systems. Safety features are built in, for example when the camera is moved by the surgeon, or when the surgeon takes his head away from the console (for example, to have a sip of coffee), the instruments freeze, and the system enters a standby mode. Publicity can come from conventional means such as the cameo role of da Vinci in the next James Bond film, performing surgery on 007's eye, as well as new information sources such as the web (table[t1]).

The future

The advantage of telemanipulation in minimising the trauma of surgery could be extended by the possibility of operating through natural orifices, leading to true non-invasive surgery. An example of this is the Singapore Inch-Worm, a device that autonomously crawls around your colon and inspects it internally, promising the ability to perform operations from within the lumen of the bowel.

Improvements in visual and motor synchronisation of telemanipulators will ensure that surgery can be performed on the beating heart. The robot arms will move relative to the variable beats of the heart, so that the image that is fed to the surgeon is still, consequently eliminating cardiopulmonary bypass. The size of the machinery is a problem, and future plans are to build these telemanipulators into the operating theatre itself. Other advances will occur in imaging, virtual reality integration, haptic sensation feedback, and superior data transfer, allowing "telementoring" to occur. Imagine you were operating and required assistance from your boss. You could ring them up, and they could seize the controls from their home and assist in your operation. This could be done on an international scale and would be a fantastic teaching tool.

Mr Jones can rest assured his prostate is safe with us.

Iain Mckay-Davies, fourth year medical student,

name, Simon Bann, specialist registrar,

Ara Darzi, professor of surgical oncology and technology,
Imperial College London


studentBMJ 2002;10:215-258 July ISSN 0966-6494