Johns Hopkins scientist programs robot to perform 'soft tissue' surgery

Not even the surest surgeon's hand is quite as steady and consistent as a robotic arm built of metal and plastic, programmed to perform the same motions over and over. And limited robotic automation is already used in surgeries involving rigid structures such as bones. But can a robot handle the slips and squirms of soft tissues during a surgery?

Simon Leonard, a Johns Hopkins University computer scientist, is part of a team that has published research showing that a robot surgeon can indeed adjust to the subtle movement and deformation of soft tissue to execute precise and consistent suturing. The research, which was published earlier this week in the journal Science Translational Medicine, promises to improve results for patients and make the best surgical techniques more widely available.

"There's a wide range of skills out there" among surgeons, says Leonard, an assistant research professor in JHU's Whiting School of Engineering. He has worked for four years to program the robotic arm to precisely stitch together pieces of soft tissue and says putting a robot to work in this form of surgery "really levels the playing field."

Soft tissue can move and change shape in complex ways as stitching goes on, requiring a surgeon's skill to respond to these changes to keep suturing as tightly and evenly as possible. According to the researchers, more than 44.5 million soft-tissue surgeries are performed in the United States each year. The published results involve a procedure called anastomosis, which is the suturing of two structures, such as blood vessels. The procedure is performed more than a million times a year in the United States. 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.

To perform the experiment, the researchers developed a robotic surgical system called the Smart Tissue Autonomous Robot, or Smart Tissue Automation Robot (STAR). 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 other robot-assisted surgical systems, it operates under the surgeon's supervision, but without hands-on guidance. A video of STAR in action is available online.

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 robot's time was longer than open and robot assisted surgery, but comparable to the laparoscopic procedure. The robotic procedure lasted 35 to 57 minutes, while the open surgery took eight minutes. By all other measures, the robot's performance was comparable or better than that of the surgeons.

"No significant differences in erroneous needle placement were noted among all surgical techniques," the researchers write, "suggesting that STAR was as dexterous as expert surgeons in needle placement …." Robotic soft tissue surgery "promises substantial benefits through improved safety from reduction of human errors and increased efficiency due to procedure time reduction."

It's not clear when the robotic system will be in use in operating rooms, but the researchers write that the intent is not to replace surgeons, but to "expand human capacity and capability."

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

Leonard worked with five co-authors affiliated with the Children's National Health System in Washington, D.C.: Azad Shademan, Justin D. Opfermann, Peter C.W. Kim, Johns Hopkins alum Axel Krieger, and Ryan S. Decker.