Perspectives
Volume 196 - Issue 8

Engineering the surgical imagination

Authors:  John A Cartmill and David Butt

Med J Aust 2012; 196 (8): 497. || doi: 10.5694/mja12.10621
Published online: 7 May 2012
John Cartmill and David Butt discuss how surgery might change with robot-like enhancements to surgeons’ capabilitiesThe advent of the surgical “robot”, exemplified by the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, Calif, USA), brings fresh approaches, possibilities and questions to the field of surgery. Because of their capacity to augment dexterity, strength, coordination and vision, ...
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John Cartmill and David Butt discuss how surgery might change with robot-like enhancements to surgeons’ capabilities

The advent of the surgical “robot”, exemplified by the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, Calif, USA), brings fresh approaches, possibilities and questions to the field of surgery. Because of their capacity to augment dexterity, strength, coordination and vision, machines like da Vinci will take surgeons beyond their current level of shared experience and vocabulary. They force us to reconceptualise operating as surgeons currently appreciate it.

Da Vinci was developed during the 1990s in the United States as a by-product of military research and advances in virtual reality technology. It found a niche with prostate surgery (as laparoscopic surgery did with cholecystectomy) and is now used for 80% of prostatectomies in the US.1 Pelvic, cardiac, trans-axillary thyroid and ophthalmic applications are emerging.2

The momentum of the surgical robotic phenomenon is a complex realisation of marketing, demographics, technology, surgical imagination and broader cultural values. Reviews in the press have suggested that marketing, spin and greed are driving the spread of robotic surgery, but the true picture is much more complex, organic and encouraging.

To call da Vinci a robot is to adopt the language of marketing and advertising. Da Vinci is technically a “servo” (from the Latin word servus, meaning slave) — it is a user-dependent rather than an independently reasoning robot that responds automatically to what it senses. The servo amplifies and enhances; it brings strength and dexterity to the dominant and non-dominant hands alike — and adds a third hand. The suggestion that the robot deskills a surgeon is implausible. The device brings coordination, technique and many other dimensions of surgery to the fore. Poor surgical technique is amplified as dispassionately as excellence.

Surgeons imagine, mentally rehearse and achieve surgery with the equipment they are used to. The advent of minimally invasive and laparoscopic surgery brought advantages but limited dexterity. The seven degrees (or more) of freedom that could be brought to bear from each hand in the “open field” was pared down to just four laparoscopically. But surgeons just got on with doing what they did with the equipment they had, quite unaware that it could be any other way.

The da Vinci device challenges the surgical imagination by returning the full range of movement enjoyed by the human arm and deploys those seven degrees of freedom within a volume of only several cubic centimetres. Da Vinci comprises three “arms”, but the degrees of freedom of each are also enhanced (eg, there are 540 degrees of pronation and supination rather than the 180 degrees we expect from our own forearm), tremor-free, strong and variably scalable (eg, the surgeon moves 3 cm while the robotic instrument tip moves 1 cm). A clutch on the controls allows the surgeon to apply their personal, limited, physiological range to the actuators, in a manner analogous to lifting and cycling a computer mouse to move a pointer across a large screen.

Da Vinci’s manipulative potential is deployed most effectively in small spaces. The challenges of prostatectomy — especially the need to see and preserve nerves while dissecting and the ability to place and tie sutures at challenging angles — have provided an “ecological niche” for da Vinci, and da Vinci’s capabilities have begun to diffuse to adjacent anatomical areas and surgical specialties. The lowest several centimetres of rectal dissection, for example, challenge the limits of conventional laparoscopic technique, yet lend themselves to the da Vinci device. A new surgical anatomy and vocabulary will develop with the development of such devices.

Da Vinci has limitations and its design idiosyncrasies will inevitably predispose to as yet unrecognised patterns of iatrogenic injury, to which surgeons must remain alert. Traditional surgery is an intimate, even sensuous, activity, with the surgeon constantly aware of the tissue sense — the feel of the tissue, its elasticity, its give and its strength. But with da Vinci, tactile, proprioceptive and kinaesthetic feedback is absent — the tissue is “mute”. This is a dangerous shortcoming; an engineering reality (one trusts) rather than a marketing strategy. Instead, a highly detailed three-dimensional high-definition image is controlled and coordinated in concert with the instruments — an assistant doesn’t “hold” the camera as in laparoscopy, the surgeon puts it and keeps it exactly where it is needed and relies on blanching and visible deformation for feedback.

A criticism of the da Vinci approach is that there is no evidence that its use achieves better results. It is true that surgeons do what they already do with the equipment they have — that’s how they came to be doing it. New tools will do what is now done, but may also provide a platform from which surgeons devise a new angle on what has heretofore not been done, or has not been done easily.

Provenance: Commissioned; not externally peer reviewed.

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