Design Considerations for Medical Device Navigation


Since minimally invasive surgery (MIS) was pioneered in the 1980s, it has become the standard of care for many procedures today. A study (Bingmer K, 2020. Feb; 34[2]) claims to show a 462% increase in cases using minimally invasive techniques between 2000 and 2018. These procedures not only change the standard of care in intervention, but they also change the patient journey during recovery, allowing patients to recover at home.

As the demand for newer, faster and safer procedures has steadily increased, so have the navigation and optical options to facilitate them. The increase in technology and methods available to help surgeons perform minimally invasive procedures presents an opportunity for surgical device designers to redesign their portfolios to better facilitate perioperative navigation. Here are some commonly encountered design challenges and some tips for solving them.

EM Nav and “renovation” of existing surgical instruments

A surgical device company’s portfolio will already include dozens of instruments that have been tried and tested with key surgical opinion leaders to meet the tightest tolerances in performing their specific tasks. In many cases, existing toolkits form the basis of surgical methods that are themselves the standard of care. Adding additional navigation capabilities presents an opportunity to deliver a dramatic increase in value and functionality in a proven system and method.

One of the easiest ways to evolve an existing surgical instrument portfolio to enable MIS is to add Electromagnetic Surgical Navigation (EM Nav) to it. This not only increases the value of the device, but also extends the life cycle of the instrument by ensuring that it keeps pace with accelerating surgical trends. Incumbents need to assess their current portfolio for opportunities and acquire or contract the right skills to determine the best path forward: either an existing platform or a bespoke system, designed to complement their toolkit . Either way, adding navigation capability will ensure that doctors and patients are better served by their products.

Additive components

EM Nav can offer added value. By adding EM Nav components to an existing OEM device, a company can bring MIS to an existing, proven surgical method, without having to reinvent the instruments themselves or change the primary mode of intervention.

Additionally, in an EM Nav system, multiple devices can be tracked simultaneously, without the need for significant additions to the surgical workflow (such as when fluoroscopy is added to aid visualization).

An EM Nav system consists of a sensor, embedded in an OEM device, which serves as the device’s location point in space; a field generator (usually placed under the patient) that creates the EM field that establishes the measurement volume; a sensor interface unit (SIU) and a system control unit (SCU) for detecting the sensor signal and converting it into position and orientation information; and a display to allow the surgeon to see the position of the instrument in three dimensions without opening the patient.

For existing surgical instruments, the first design challenge is determining how to attach the sensor to the instrument itself. Additional components must:

  • Isolate the tip position as precisely as possible, this often means placing a new component on the device closest to the distal end.
  • Connect to the IUS/SCU, usually located outside the sterile field.
  • Being able to consistently activate in the EM field, regardless of orientation in space.
  • Be biocompatible and not interfere with the procedure itself.

Each of these requirements has its own specific design challenges associated with it; however, they can be summarized as the addition of physical components to an existing platform which at the same time adds new functionality and does not take away from the existing and proven function of the device. As device engineers can attest, even simple, minor design changes can ripple through the device, all the way to manufacturing, causing aggravating headaches, extending lead times, and increasing budgets.

The decision to make or buy

With few exceptions, trends towards MIS will put pressure on the surgical instruments market to ensure that their devices enable these methods of intervention. Companies looking at their instrument portfolio should think about how to integrate MIS into it, and so they will be faced with an overall “do” vs. “buy” decision that is more complex than perhaps typical.

Embarking on a program to add EM Nav to an existing toolkit will require the engineering department to examine its internal talent to determine if it has the availability as well as the appropriate skills to develop such a system. Project managers can also, during the pre-planning phase, consider in-house manufacturing capabilities to determine if a retrofitted device can be manufactured in-house or if the company will need a marketing partner.

Program managers who conduct this analysis and find troubling gaps may be tempted to seek out a partner with an existing platform that they claim is “ready to integrate.” The authors caution decision makers to keep in mind that protecting the integrity of the original device is paramount to adoption by physicians, and that no existing system will be barrier-free to integrating design. Additionally, given the pace of change in the industry, companies would do well to remain as flexible as possible, to minimize the impact of third-party software or hardware upgrades.

It’s often best to bring in experts as early as possible to evaluate the program, educate on available solutions, and help draft the requirements for the specific application. This could be referred to, in the context of a phase gate process, as “Phase 0”. Then program managers and their partners can make a much more informed decision about which process is moving forward and what kind of trade-offs to make and come up with a comprehensive plan for them.

New surgical optical systems

MIS includes all minimally invasive surgeries, including those where direct visualization is paramount to the success of the procedure. Companies wishing to add direct visualization to their portfolio of instruments will need to develop a stand-alone system that is specifically compatible with the tools and methods already established and validated.

Given the trends in the specific intervention that a company offers, doctors can be better served by companies developing their own complete optical system (or an optical system compatible with existing surgical visualization platforms). Although it is often desirable to start a new product development program with a real “blank page”, for companies that discover surgical optics, there are new pains to keep in mind.

What got you here won’t get you there

Unlike the development of an EM navigation system of personalized concept, which often requires the purchase of individual components and the construction of sub-assemblies, engineers have the possibility of building a prototype surgical optical system using of existing commercially available sub-assemblies. Although this may accelerate certain concept proof works at an early stage to demonstrate usefulness and value, these systems are almost never able to evolve during development and will need most if not all their sub systems redesigned to be compatible with application requirements.

Given the way phase gate programs are run, it can create a false sense of progress when phase 1 yields a working prototype that needs to be completely redesigned in phase 2. This can cause managers and sponsors to panic From the program, reaching out to potential partners who are fragmented and forced to work in a confined space so as not to derail the program.

From the perspective of verification, validation and marketing, these subsystems used for prototyping will have individual components often very difficult to find. If you have based your design on something with exceptionally long delivery times, or if a component is locked in an assembly and the teams are looking for basic components, this may also have a significant impact on the deadline for market, cost of goods, and just being able to build enough devices to support testing.

Leave where you are

If direct visualization is the means of bringing the surgical portfolio of your business in the space put, it is best to start at the start. As with EM Nav, the initial work must be focused on correct integration of the system and have in mind all the life cycles of the program and the product from the start, as the program takes shape and is sized ( in terms of time, cost, risk, market value, etc.). The scalability of marketing is essential, and it is very common for companies engaged in these programs to fight downstream to obtain optical components sourced, assembled and aligned in the strict tolerances required by optical systems. It is also difficult to reach the numbers needed for validation.

The opportunity presented by the presence of a tailor -made optical SIG system in the portfolio cannot be overestimated, but neither is complexity and risk. The companies in place are well advised to consider using a design-development partner as soon as possible, if only to ensure that an experienced voice is available to discuss potential traps throughout. As with a new EM NAV system, the addition of a “phase 0” before the program goes to planning protects against the risks downstream of derailing the program late in the chronology.

Surgical guidance is the trend

The tendency towards mini-invasive surgeries does not slow down, and now that payers have discovered that convalescence at home represents a significant cost economy, the desire to return patients to their homes earlier will only create more opportunities for companies to serve this market.

Companies of surgical instruments in place already work to allow validated surgical methods and should therefore be at the forefront of the development of this new generation of devices. Whether it is to modernize existing OEM instruments or add new optical instruments to the portfolio, the risks are clear, but careful prior planning with established experts can help save time, money and headache.


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