Robot ‘wrist’ developed at Vanderbilt University

Tiny mechanical wrist could give needlescopic surgery a new degree of dexterity

A research team headed by Robert Webster, associate professor of mechanical engineering at Vanderbilt University, Nashville, Tenessee has developed a surgical robot with steerable needles equipped with wrists that are less than 1/16th of an inch (2 mm) thick.

Needlescopic surgery, which uses surgical instruments shrunk to the diameter of a sewing needle, is the ultimate form of minimally invasive surgery.

The needle-sized incisions it requires are so small that they can be sealed with surgical tape and usually heal without leaving a scar.

The new device is designed to provide needlescopic tools with a degree of dexterity that they have previously lacked.

The design uses a nitinol tube with a series of slots cut down one side.

The slots cause the rigidity of the tube to decrease and by pulling on a small wire that runs inside the tube, make it bend by 90 degrees.

The wrist springs back to a straight position when tension on the wire is released.

This could allow surgeon-operators to perform a number of procedures such as precise resections and suturing that haven’t been possible before and could also allow the use of needles in places that have been beyond their reach, such as the nose, throat, ears and brain.

S Duke Herrell, professor of urological surgery, who is consulting on the project, said: “The smaller you can make surgical instruments the better . . .as long as you can maintain an adequate degree of dexterity.

This ‘wrist’ would allow us to do surgeries that at present require much larger incisions and may even enable us to perform operations that are not feasible at present.”

Team members would like to test the system by using it for ‘transnasal’ surgery: operations to remove tumours in the pituitary gland and at the skull base that traditionally involve cutting large openings in a patient’s skull and/or face.

Studies have shown that using an endoscope to go through the nasal cavity is less traumatic, but the procedure is so difficult that only a handful of surgeons have mastered it.

“It should be useful for a number of other operations as well,” said Webster. “We think once we give this tool to surgeons they will find all kinds of applications we haven’t thought of.”

By the end of the summer, the team hope to have completed the control software and the interface that allows the surgeons to operate the device.

The team at Vanderbilt University are actively looking for a commercial partner who will take the new instrument through the FDA approval process including initial clinical trials.

Webster said: “Our best case scenario is that the system could be available to surgeons in four to five years.”