Remote surgery techniques

Supplier: Maxon Motor - Medical & Surgery
19 May, 2010

Remote surgery techniques promote minimally invasive surgery.

Not so far in the future, a patient will be lying in a small local hospital and a world-renowned surgeon will be operating on him or her from America via the Internet.

Such operations will be carried out by robotic arms, driven by what seems like ghost hands. These arms will be set up by the attending medic and guided remotely by the surgeon.

Proponents of telesurgery envision early applications of this technology even further afield – in outer space. They argue that the technology needed is already available: precise servomechanics, force-feedback sensors for tactile feel, motion scaling software, communication links and the algorithms necessary for motion control.

These are the features of the computer-enhanced, minimally invasive surgery systems (MIS) introduced by Intuitive Surgical Inc. (Mountain View, CA) which is already used in dozens of ways.

A new technology that was specifically developed for applications involving telesurgery combines the surgeon's natural hand movements with the traumatic approach of MIS. Initially the clinical focus of the Intuitive system was on heart surgery, but since then, it can be used in a whole array of surgical disciplines such as urology, gynaecology and thorascoscopy.

Seven degrees of freedom
An operation usually proceeds as follows: the surgeon makes tiny incisions less than 1 cm wide and inserts special tubes called cannulas. These tubes create ports into the body and protect surrounding tissue. Three robotic arms are then manoeuvred into position. Each arm acts as a carriage, on one hand for the endoscope and on the other for the pencil-thin tools to be inserted through the incisions.

A sliding coupling holds the tool to the arm. Three motors control the arm movements. Two drive the arm forwards and backwards, left and right; the other moves the coupling up and down. Together they replicate the three degrees of freedom of the surgeon’s shoulder and elbow motion.

EndoWrist technology at the end of each tool provides four additional degrees of freedom: inner pitch and yaw, roll and grip. Inner pitch is the movement the human wrist makes when one knocks on a door. Inner yaw is the side-to-side movement associated with waving or wiping a table.

Four 25 mm motors housed at the base of each robotic arm drive the EndoWrist via piano strings, while four digital signal processors (DSPs) comprise the Intuitive system was on heart surgery, but since then, it can be used in a whole array of surgical disciplines such as urology, gynaecology and thorascoscopy.

Remote interface
The surgeon, while viewing the 3D video feed, controls the tools through familiar hand movements. Rather than bending over the patient, he or she operates from a seated position with the arms in a natural and relaxed orientation.

Motion scaling software embedded in the motor controller translates the surgeon’s large natural movements into extremely precise micro-movements. This software also translates every movement the surgeon makes to an identical, though scaled-down movement, at the surgical site.

With Intuitive's minimally invasive surgical system, surgeons manoeuvre tools via remote hand movements. Motion controllers and force feedback data reproduce these movements in the surgical field. Without such software, other MIS systems are counter-intuitive, reversing the surgeon’s natural motion. This is because the surgical tools pivot against the point at which they enter the body. Motion scaling software, combined with the EndoWrist technology, enables the surgeon to reach delicate body structures as if he or she were performing the operation directly.

"Such innovations", claims Frederic Moll, MD and co-founder of Intuitive Surgical Inc., "will not only promote the use of minimally invasive surgical interventions, but the associated benefits: faster recovery times, fewer complications, and better healing." As Moll points out, "MIS technology has only begun to make its impact felt, comprising just 15% of all surgeries today."

And telesurgery? "Technically, we have the tools to do it," says Marketing Director Daniel Hawkins, "but the present focus is still in the operating theatre."

The company
maxon motor ag in Sachseln, Switzerland is an innovative and dynamic company. It has been developing, producing and distributing precise DC micromotors with the worldwide patented ironless rotor, System maxon, since 1970.

Together with subsidiaries in 11 countries and other exclusive dealerships, the company has become one of the world’s leading suppliers of drive systems.

The workforce of 1,600 staff generated consolidated sales in 2007 of CHF 300 million, more than double that of 2002. Its overseas sales account for 80%.

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