A robot has for the first time carried out fully autonomous surgery on a live subject: an intestinal anastomosis on a pig, during which two loops of intestine were stitched together. Four surgeries were carried out and all the subjects survived without complications.
Detailed in a paper in Science Translational Medicine, the Smart Tissue Autonomous Robot (STAR) was created by a team of surgeons and scientists at the Sheikh Zayed Institute for Pediatric Surgical Innovation at the USA's Children's National Health System in Washington, DC. As well as live (in vivo) surgery, STAR also carried out surgeries on inanimate (ex vivo) porcine tissue, including both intestinal anastomosis and linear suturing.
When compared to the intestinal anastomosis procedures carried out both manually by experienced surgeons and with existing robot-assisted surgical techniques using the daVinci Surgical System, STAR was found to outperform both in terms of surgical quality. The results of the procedures were assessed on factors such as "consistent suture spacing, which helps to promote healing, and in withstanding higher leak pressures, as leakage can be a significant complication from anastomosis surgery".
However, STAR currently takes longer than a surgeon working manually: 35 minutes, to a human's eight minutes. Its time is comparable to the time it takes humans to carry out laparoscopic intestinal anastomosis – keyhole surgery that relies on tiny cameras to track progress and haptic feedback instruments to do the suturing.
Dr Peter C. Kim said that "the intent of this demonstration is not to replace surgeons, but to expand human capacity and capability through enhanced vision, dexterity and complementary machine intelligence for improved surgical outcomes." STAR is designed to improve the accuracy of always-challenging soft tissue surgery, allowing a human surgeon to invest their expertise by supervising the procedure and interrupting if necessary, while the robot plans and performs the soft tissue sutures.
Technical lead Axel Krieger says that "by using novel tissue tracking and applied force measurement, coupled with suture automation software, our robotic system can detect arbitrary tissue motions in real time and automatically adjust." Until STAR's development, says Krieger, "autonomous robot surgery has been limited to applications with rigid anatomy, such as bone cutting, because they are more predictable."
STAR tracks the position of flexible soft tissues using near infrared florescent (NIRF) markers applied to the areas it needs to suture, monitored by a camera system that's able to see in three dimensions. An intelligent algorithm guides the robot's surgical plan and allows it to autonomously adjust and react in real time as tissue moves. It also has finely calibrated force sensors and actuators and an articulated laparoscopic suturing tool with eight degrees of movement – one more than the human arm, according to Science, which also provides video footage of the robot performing surgery on inanimate tissue.
Dr Kim says that the next step in STAR's development will be to create improved sensors and further miniaturise the tools used by the robot. He says that, if the team can find a suitable partner to develop the technology, we could be seeing it in clinical use in as little as two years.