A new robot helps surgeons suppress tremors during reconstructive microsurgeries and allows more of them to perform those delicate tasks.January 08, 2018
Most surgeons do not have the dexterity to stitch together small blood vessels when doing reconstructive surgery. Even the hands of skilled surgeons tremor when performing the task. A new surgical robot developed by Dutch startup MicroSure seeks to suppress those tremors while increasing the number of surgeons who can perform this delicate task.
During the last few months, the experimental microsurgical robot has been proving itself twice weekly at Maastricht University Medical Center in the Netherlands. There, plastic surgeon Shan Shan Qiu Shao has been using the robot to connect blood and lymphatic vessels whose diameters range in size from 0.3 and 0.8 millimeters, or roughly half the size of the head of a small sewing pin.
The surgeries treat lymphedema, a swelling of the lymphatic system that is often a complication of breast cancer surgery. The lymphatic system contains protein-rich fluids that entrain waste, bacteria, and viruses and filter them through the lymph nodes.
When surgeons remove tumors from the breast, they often cut out lymph nodes as well. When there are not enough lymph nodes to drain the wastes, lymphatic fluids build up in the body and cause swelling. Usually, patients can wear wraps or compression sleeves or elevate their limbs until the problem passes after four to six weeks.
More severe cases require surgery. In the past, that involved removing excess tissue from arms or legs. The surgery Qui Shao performs takes a different route: She surgically reroutes the clogged lymphatic vessels so they drain into blood vessels.
Blood and lymphatic vessels whose diameters average only 0.5 mm are extremely small, even for microsurgeons, Qiu Shao says. Even the most skilled surgeon needs a microscope to work with them. The higher the magnification needed to see the vessel, the more noticeable the tremor in her hands, she says.
She finds the MicroSure device is “more stable and precise than a tremoring hand.”
The MicroSure robot solves that problem by taking a master-slave approach, that is, it duplicates her hand motion but at a much smaller scale.
MicroSure starts with a pair of joystick-like devices designed to hold standard surgical instruments like scalpels, clamps, and tweezers. The joysticks move with six degrees of freedom, plus an additional degree of freedom so surgeons can pinch tweezers or other tools. The surgeon grasps the instrument, which feels and moves in a familiar manner, Qiu Shao says.
The same surgical instruments are inserted into the robotic arms, so they act as its effectors. The surgeon then sits near the patient, looks through the microscope, and manipulates the instruments to conduct the procedure.
As the surgeon manipulates the joystick, the MicroSure robot tracks and measures the movement and sends the information to the robotic arms. The arms smoothly duplicate those motions at a smaller scale. When Qui Shao looks through the microscope, she sees only a pair of instruments moving in ways she’s used to seeing when operating by hand.
The robot suppresses random tremors and unwanted movements that are unavoidable during microsurgery, Qiu Shao says. Using a floor pedal, Qui Shao can also control the extent to which she scales down the ratio of hand/machine motion. This enables her to use larger motions to manipulate the position of a vessel or clamp and smaller movements to tie a suture.
In some ways, MicroSure’s surgical robot resembles the better known da Vinci surgical system. Both are master-slave systems, both suppress tremors, and both use foot pedals to control the scale of robotic movements.
Yet MicroSure differs in important ways, says Raimondo Cau, the company’s chief technology officer. Cau began working on the robot as a Ph.D. student at Eindhoven University of Technology in in Eindhoven, Netherlands. MicroSure is a spinoff of that school and Maastricht University Medical Center, also in the Netherlands.
Da Vinci, Cau explained, was designed for minimally invasive surgery, allowing surgeons to use cameras and a long robotic arm to reach deep within patients’ bodies through a small incision. The system is large and averages about $2 million. MicroSure has yet to establish a final price for their robot, but Cau believes it will sell for between $200,000 and $300,000.
The robot is designed for open body surgery. The robot provides haptic feedback to surgeons, so they can feel the interplay of forces when working with delicate vessels or nerves. The company also works with conventional rather than proprietary surgical instruments.
The key contribution of the microrobot is that it broadens the pool of surgeons who can perform microsurgeries by suppressing tremors, which affect all surgeons operating below 1.5 mm and worsens as surgeons age.
Cau, who began creating the device in 2009 as the project for his doctorate degree, worked with surgeons to give them what they wanted. For example, in response to surgeons’ request, the device works with operating rooms’ existing microscopes and surgical tools. It also enables surgeons to sit, which is far less draining than standing hunched over while performing hours of intricate surgical procedures.
Cau says there are no added clinical risks compared to conventional, manual microsurgery because the device operates as an extension of the surgeon’s hands. The surgical planning, workflow and operation techniques are unchanged, he says. The surgeon makes all clinical decisions and is always controlling the movements made by the device.
MicroSure’s robot is currently undergoing clinical trials with approval from Conformity European (CE,) the European equivalent of the U.S. Food and Drug Administration.
Ultimately, Cau hopes surgeons will use the robot to perform even more difficult operations, such as breast reconstruction using flaps of skin and fat tissue from the patient’s belly. The success of such surgeries depends on the extent to which the surgeon can attach blood vessels and nerves. If the blood flow is poor, the flap will die.
Cau was thrilled that he was able to stand beside the first patient operated on with the device, then follow up by talking with her and seeing how she was doing.
“As a mechanical engineer, I wanted to be able to build the whole machine and see how it was being implemented and used by the customer,” he says. “I wanted to have an impact. The best way was to develop medical technology that can improve people’s lives. As an engineer, that was a really noble cause for me.”
Theresa Sullivan Barger is an independent technical writer.
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