Laparoscopy places great demands on surgeons, however. They have to wield very long, thin instruments, working through small pivot points cut into the patient’s body. This requires instruments to be held in awkward positions for long periods, potentially causing fatigue, repetitive strain injuries, neck and back problems. It can also limit the number of hours during which older surgeons can operate.
Robotic devices have been introduced in recent years that hold these instruments in place, freeing up staff from the physically demanding task of holding them completely still for the duration of the operation. However, the few robotic systemsthat are currently available are relatively bulky and expensive.
CMR Surgical – previously Cambridge Medical Robotics, was set up in 2014 with the aim of solving these problems.
Luke Hares, CMR Surgical’s technology director outlines that “Fundamentally, we’re trying to solve a big problem: the restricted availability of laparoscopic surgery because surgeons don’t have a good enough tool.”
To this end CMR has developed Versius, a system that includes a set of ‘wrists’ that allow the robotic arms to mimic the way human surgeons hold them. Additionally, all the motors involved in moving the robotic arms are contained within them rather than in a control box under the operating table. This makes Versius much more compact and allows it to be disassembled easily in order to be moved to where it is needed rather than remain static in one operating room. Hares highlights the system’s ease of use, saying that rather than taking 30 hours for a surgeon to learn to tie a knot using manual laparoscopic tools, he could teach anyone how to do it with Versius in 30 minutes.
“Everything in the Versius design is about driving up utilisation,” he explains. The critical design element that enables that, he explains, is the robot arm wrist joint.
“If you look at a conventional industrial robot,” he says. “What you’ll see is that the wrist joint is made up of three joints: a roll joint in the forearm; a pitch joint; and then a roll joint at the end. That’s enough to rotate a payload in any particular direction.”
This is fine if you want to hold instruments at a 90º angle, Hares says, but to hold them straight out like a surgeon would mean the roll joints would be parallel, instantly losing one degree of freedom. This would mean it is possible to move the instrument up and down, but the whole robot would need to rotate 90º to allow left and right movement, which is unacceptable in surgery as you need free range of movement.
“Our wrist design, rather than having three wrists, has four,” Hares continues. “The two middle joints form a coaxial pitch/yaw. Essentially, it’s a driven universal joint. That gives us the flexibility and the ability to do the surgery, but with a robot arm that’s small enough to fit round the patient.”
Versius uses conventional electric motors controlled by power and control electronics developed using electronic manufacturing technology from the mobile phone industry, all of which is contained within the arms of the robot. CMR’s electronics design engineers and mechanical engineers had to work extremely closely to provide a fully-integrated system that is both lightweight, strong and stiff.
Every joint on the system has a torque sensor that monitors how much force it is exerting and can respond accordingly. This sopistication in the sensing is matched by the robotics and software to provide what is claimed to be a straightforward interface for the user.
Although the system provides haptic feedback to the surgeon to warn when they are close to exceeding range limits on the arms, haptic feedback is not currently a feature of the Versius. This is because surgeons have never had very good ‘feel’ through manual tools. However, haptics are being considered for future iterations of the system.
Another area of advance offered by medical robots is the ability to use a stereo endoscope, which is twice as heavy as a standard endoscope and combats the loss in depth perception encountered by surgeons.
“We can then feed that [extra data] to a 3D medical monitor that the surgeon views wearing glasses that use the same basic technology as 3D cinema,” says Hares. “It’s just like it’s laid out in front of you, expect it’s magnified and better lit.”
CMR expects the Versius to gain regulatory approval by the end of 2018, whereupon the ‘significant number of units’ it wants to place into hospitals will be ready to start working.
Hares likens Versius to modern mobile phones, which have, he says, “enabled huge swathes of the world to jump easily from traditional telephone technology to the latest way of doing it”.
“Ultimately, we anticipate this being a global product,” he concludes. “There are six million people a year getting open surgery who should get keyhole surgery. To solve that problem will require many thousands of systems out in the world.”