A robot for ‘soft tissue’ surgery outperforms surgeons

Let's say you're having intestinal surgery. Which do you choose: human or robot surgeon?
May 4, 2016

The STAR robot suturing intestinal tissue (credit: Azad Shademan et al./Science Translational Medicine)

Can a robot handle the slippery stuff of soft tissues that can move and change shape in complex ways as stitching goes on, normally requiring a surgeon’s skill to respond to these changes to keep suturing as tightly and evenly as possible?

A Johns Hopkins University and Children’s National Health System research team decided to find out by using their  “Smart Tissue Autonomous Robot” (STAR) to perform in a procedure called anastomosis* (joining two tubular structures such as blood vessels together), using pig intestinal tissue.

The researchers published the results today in an open-access paper in the journal Science Translational Medicine. The robot surgeon took longer (up to 57 minutes vs. 8 minutes for human surgeons) but “the machine does it better,” according to Peter Kim, M.D., Professor of Surgery at the Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System in Washington D.C. Kim said the procedure was about  60 percent fully autonomous and 40 percent supervised (“we made some minor adjustments”), but that it can be made fully autonomous.

“The equivalent of a fancy sewing machine”

Automating soft tissue surgery. Left: The STAR system integrates near-infrared fluorescent (NIRF) imaging of markers (added by the surgeon to allow STAR to track surgical motions through blood and tissue occlusions), 3D plenoptic vision (captures the intensity and direction of the light rays emanating from the markers), force sensing, submillimeter positioning, and actuated surgical tools. Right: surgical site detail during linear suturing task showing a longitudinally cut porcine intestine suspended by five stay sutures. (credit: Azad Shademan et al./Science Translational Medicine)

STAR was developed by Azad Shademan and associates at the Sheikh Zayed Institute. It features a 3D imaging system and a near-infrared sensor to spot fluorescent markers along the edges of the tissue to keep the robotic suture needle on track. Unlike most other robot-assisted surgical systems, such as the Da Vinci Si, it operates without human hands-on guidance (but under the surgeon’s supervision).

In the research, the STAR robotic sutures were compared with the work of five surgeons completing the same procedure using three methods: open surgery, laparoscopic, and robot assisted surgery. Researchers compared consistency of suture spacing, pressure at which the seam leaked, mistakes that required removing the needle from the tissue or restarting the robot, and completion time.

The system promises to improve results for patients and make the best surgical techniques more widely available, according to the researchers. Putting a robot to work in this form of surgery “really levels the playing field,” said Simon Leonard, a computer scientist an assistant research professor in the Johns Hopkins Whiting School of Engineering, who worked for four years to program the robotic arm to precisely stitch together pieces of soft tissue.

As Leonard put it, they’re designing an advanced surgical tool, “the equivalent of a fancy sewing machine.”

* Anastomosis is performed more than a million times a year in the U.S.; more than 44.5 million such soft-tissue surgeries are performed in the U.S. each year. According to the researchers, complications such as leakage along the seams occur nearly 20 percent of the time in colorectal surgery and 25 to 30 percent of the time in abdominal surgery.

Carla Schaffer/AAAS | Robotic Surgery Just Got More Autonomous

Abstract of Supervised autonomous robotic soft tissue surgery

The current paradigm of robot-assisted surgeries (RASs) depends entirely on an individual surgeon’s manual capability. Autonomous robotic surgery—removing the surgeon’s hands—promises enhanced efficacy, safety, and improved access to optimized surgical techniques. Surgeries involving soft tissue have not been performed autonomously because of technological limitations, including lack of vision systems that can distinguish and track the target tissues in dynamic surgical environments and lack of intelligent algorithms that can execute complex surgical tasks. We demonstrate in vivo supervised autonomous soft tissue surgery in an open surgical setting, enabled by a plenoptic three-dimensional and near-infrared fluorescent (NIRF) imaging system and an autonomous suturing algorithm. Inspired by the best human surgical practices, a computer program generates a plan to complete complex surgical tasks on deformable soft tissue, such as suturing and intestinal anastomosis. We compared metrics of anastomosis—including the consistency of suturing informed by the average suture spacing, the pressure at which the anastomosis leaked, the number of mistakes that required removing the needle from the tissue, completion time, and lumen reduction in intestinal anastomoses—between our supervised autonomous system, manual laparoscopic surgery, and clinically used RAS approaches. Despite dynamic scene changes and tissue movement during surgery, we demonstrate that the outcome of supervised autonomous procedures is superior to surgery performed by expert surgeons and RAS techniques in ex vivo porcine tissues and in living pigs. These results demonstrate the potential for autonomous robots to improve the efficacy, consistency, functional outcome, and accessibility of surgical techniques.