Surgical Robotics Benefits From Emerging Shape Sensing Technology
Surgical Robotics has seen rapid growth since Intuitive Surgical’s introduction of the Da Vinci platform in the early 2000s.
This trend comes as no surprise; robotics brings an unprecedented level of control, flexibility, repeatability, and safety to an increasing number of minimally invasive procedures. It is enabling surgeons to make easy work of even some of the most complex cases. With the likes of Johnson and Johnson, Stryker, Medtronic, Siemens Healthineers, and many more jumping into the fray, it is clear that robotic solutions are going to play a central role in the future of medical technology.
Whether it is navigating the tortuous anatomy of the pulmonary and cardiovascular systems or maintaining stability during knee replacements and spine screw installation, positional awareness and control is a key element of any surgical robotics procedure. While coarse placement and movement is straightforward using precision motors and rigid robotic arms, difficulties arise when it comes to the instrumentation that is normally placed at the end of these actuators.
Drill guides, needles, bone removal devices, and especially endoscopes and catheters are anything but rigid, and knowing and controlling their position is a challenging but essential factor in a robotic solution’s value. This has resulted in a growing need for integration of accurate and reliable localization sensor technology. Position and orientation information from such sensors are being fused with a surgeon’s inputs and advanced algorithms to create cutting-edge navigation and control solutions. These implementations are a driving force behind the efficacy of surgical robotics platforms and can make or break the adoption of a product.
Historically there have been two solutions for obtaining the position and orientation of surgical robotics instrumentation: infrared optical measurements and electromagnetic tracking. Each of these has their own set of advantages, limitations, and ideal areas of application. Infrared optical technologies, for example, are highly accurate but require line of sight to make a measurement.
The infrared emitter and receiver must be carefully placed to be in constant view of the tracked device, so these solutions are commonly found in knee replacement, spinal, and other orthopedic procedures where the instrumentation remains mostly external to the patient. Electromagnetic tracking devices have the benefit of being able to be placed inside the anatomy, however, they must remain within a specified volume and any electromagnetic interference (EMI) must be minimized for these solutions to produce reliable measurements.
While requirements such as line of sight and EMI reduction are being implemented with success, such limitations can place many undesired constraints on clinical workflows and engineering designs. In addition, these methods provide the position and orientation of a single or limited number of locations, such as the handle of an orthopedic tool or the distal end of an endoscope. While this information is certainly useful, it would be hugely beneficial to understand the location, orientation, and movement of the entire device, particularly when it comes to highly flexible tools such as endoscopes and catheters.
This is where fiber optic 3D shape sensing can bring significant value to robotically driven instrumentation. The Shape Sensing Company (TSSC) technology provides up to eight thousand, six degree of freedom measurements along the length of a 1.25 meter long optical fiber. When integrated into the length of a medical device, it provides not only the location and orientation of its distal end, but it clearly informs surgeons and control algorithms of what the entire device is doing anywhere along its length.
This capability can trigger some massive leaps forward in robotic navigation and control. Engineers will have spatially continuous measurements available for closed loop control of the entire length of catheters, endoscopes, and a variety of other flexible instrumentation. This enables schemes such as follow-the-leader, position hold, motion compensation, looping prevention, and many others. Fiber optic 3D shape sensing also provides surgeons and staff with an unrestricted, rotatable, real-time, three-dimensional view of the entire device.
When registered to and overlaid images of the anatomy, this serves as a crystal clear and intuitive a visual aid in navigating complex and tortuous anatomy and mitigates the need for fluoroscopy. The technology also provides continuous distributions of bending radius and twist. Surgical robotics platforms can utilize these measurements to constantly assess the tortuosity of a navigated path, its effect on maneuverability, and avoid strain energy buildup and whipping upon its release. These unique visualization, navigation, and control capabilities, coupled with its immunity to environmental interference and unrestricted working volume, make fiber optic 3D shape sensing a powerful tool in the world of surgical robotics.
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