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Robotics and navigation provide surgeons with procedural precision—a benefit that comes from total system design and manufacturing, including instruments.
“Your system accuracy is only as good as the weakest link or least-accurate component. One of the critical elements of the system is the surgical instruments themselves,” said David Simon, Ph.D., Vice President of Robotics R&D, Strategy and Business Development at Medtronic.
Orthopedic device companies expanding their digital tool offerings will need to commercialize instruments that require more advanced accuracy than what is used in handheld surgical procedures. Knowing this, device companies and suppliers are wisely asking what it will take to thrive in instrument manufacturing moving forward.
On the heels of Medtronic’s Mazor X Stealth Edition launch, we asked Dr. Simon his perspective on the role that instruments play in robotic and navigation R&D and manufacturing, as well as his outlook on future instrument innovation.
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How does the use of a robotic arm and navigation affect your approach to instrument design and manufacture?
Dr. Simon: Medtronic has developed navigation systems and instruments in the spine space for over 20 years. The requirements, specifications, designs and standards for navigated instruments are not that different than they are for robotics. Most of these navigation or robotic systems have system-level accuracies in the range of 1 to 2 millimeters. Imagine an instrument that is 30 centimeters long holding tolerance from one end to another significantly below the millimeter level. From a design perspective, understanding specifically the mating or the interfaces between one component and another is the area where particular attention has to be made in order to achieve accuracy requirements.
Design is only one element in order to achieve that accuracy. In addition to design elements, we must also account for manufacturing methods, process qualifications, validated inspection methods that are capable of achieving accuracy goals.
To your preface about manufacturing engineers or manufacturing groups asking what does it take to be successful in this space, we have had some contract manufacturers who thought they would be able to deliver the necessary tolerances, but what they found was that their techniques or their equipment didn’t allow sufficiently high yields; therefore, the cost of those instruments was driven up significantly.
Successfully commercializing navigation and robotic instruments requires an end-to-end systematic approach to design, validation and manufacturing. There is an added component that these are typically reusable instruments that have to go through cleaning and sterilization cycles, and the cleaning and sterilization that occurs can be in some cases even more aggressive, stressing the instrument from a rigidity perspective.
How have you expanded internal or external expertise and capabilities in order to provide instruments that are used with your robotic and navigation technology?
Dr. Simon: Within our business, we have hired mechanical instrument engineers with expertise in precision design and manufacturing. I want to go back to the importance of the interface mechanism. If you look at the interface between an instrument and a robotic device, you have to hold tolerances through that interface. We have a strong group of engineers with the expertise in those areas.
Regarding outside manufacturing groups, we have come to learn over time which ones are capable of precision manufacturing operations and which ones aren’t able to hold tolerances. It may not be a big surprise that some of the manufacturing groups that are capable of building standard instruments have not been able to make that leap to robotic or navigation instrument manufacturing. There is a lot of time spent on the supply chain selection process and vetting suppliers.
Also, we invest a lot in advanced manufacturing engineers within our company to make sure that the designs can be translated to manufacturable processes. There is collaboration between our advanced manufacturing engineers and the manufacturers themselves to be able to bring these products to market.
What are your predictions for the ways that instruments will change as robotics, navigation—and future digital tools—advance in orthopedics and spine?
Dr. Simon: Today’s instruments tend to be long to ensure sufficient reachability; they have to extend from the anatomy of interest to the attachment point on the robot. The longer they are, the more rigid they need to be, which means heavier instruments for structural rigidity. There is a big focus on developing lighter and smaller instruments to improve the ergonomics and workflow. That may include new materials or perhaps new solutions and designs.
We have already integrated multiple technologies within our product portfolio to develop enhanced procedural capabilities. For example, our Midas Rex high speed drills have been coupled with our navigation tracking technology to deliver the ability to very precisely navigate the tip of these high speed drills. We’ve integrated nerve integrity monitoring into powered instruments, which are also navigated. I envision a continuation in this trend of combining and integrating our unique ecosystem of technologies.
We are researching sensing technologies that can be integrated into surgical instruments to help ensure safer surgeries and better outcomes. For example, sensors that have the ability to differentiate soft tissue structures such as nerve roots or the spinal cord from bone can be used to help ensure safer bone cutting, therefore improving the ability to perform critical portions of spine surgery, such as bony decompression.
Lastly, we are looking at new types of surgical instruments and new modalities of delivering an action to the anatomy. Today, people think of mechanical devices when they think about instruments, but there is a lot of opportunity in looking at the electromechanical world, forms of energy delivery that may have value in spinal procedures. Our vision is ultimately to work with our surgeon collaborators to transform spinal surgery, and we believe that these new advanced capabilities, both on the sensing side and on the energy delivery side, have the potential to really do that.
Can you provide examples of what you mean by energy delivery and new materials?
Dr. Simon: An energy delivery example would be that bone cutting has historically used high-speed rotational cutting devices. There are a number of companies that use ultrasonic bone cutting, vibrating a bone cutting device at extremely high speeds and changing the fundamental nature of bone cutting. In that case, the ultrasonic bone cutting capability has some degree of tissue selectivity so that it preferentially cuts bone over soft tissue. I’ve heard it likened to jackhammering a hard piece of rubber—it will bounce off of the rubber. If you take that jackhammer and put it on a piece of concrete, it will cut right through it. Imagine applying that concept to bone vs. soft tissue in spinal bone cutting.
Regarding materials, the example I gave earlier was preserving structural rigidity while reducing weight. You can imagine a number of materials one might use for that purpose—for example, carbon fiber. Most of the spatial tracking that has been done in navigated and robotic spine surgery has historically used optical localization systems; however, we at Medtronic have been selling electromagnetic localization technologies for many years. One of the environmental confounders for electromagnetic technology is ferrous metals or metals that generate eddy currents and then create inaccuracies in electromagnetic measurements. We have learned over the years that there are certain types of metals, certain grades of stainless steel for example, that have less distortion for electromagnetic localization. As we begin to look forward at the ability to track individual vertebral segments using electromagnetic localizers, that material selection will be an important consideration.
Do you have any closing comments?
Dr. Simon: One final thought. Given the system-level thinking, the design and testing that has gone into our products and the critical role that well-designed instruments play, it is imperative that only Medtronic designed and manufactured instruments be used with our robotic and navigation systems in order to maintain patient safety.
Images courtesy of Medtronic
