The U.S. Food and Drug Administration (FDA) 510(k) pre-market process is designed to be a streamlined regulatory pathway allowing medical devices to gain market clearance through demonstrating substantial equivalence to FDA-cleared predicates. This process includes stepping out onto the regulatory dance floor with confidence, choreography, and a heck of a dance partner. In reality, this can sometimes leave the small businesses feeling like they’re left standing on the wall of the dance with no partner. 

For many Class II medical devices, the regulatory pathway to market is through a 510(k) where the sponsor must demonstrate safety and effectiveness of their device against a currently marketed predicate. According to FDA’s guidance document “The 510(k) Program: Evaluating Substantial Equivalence in Premarket Notifications [510(k)] Guidance for Industry and Food and Drug Administration Staff” a 510(k) submission aims to “demonstrate that the new device to be marketed is ‘substantially equivalent’ to a legally marketed device.” 

Rarely is a new device perfectly identical to a predicate; the more unique the subject device, the more eight-counts are added to the dance routine. To account for this, the FDA’s guidance document includes a more flexible approach to determining substantial equivalence to “accommodate evolving technology while maintaining predictability and consistency to promote confidence among device developers, practitioners, and patients.”

The dance floor can be an intimidating place for small businesses. Established medical device companies seem to glide effortlessly with their years of experience and access to internal predicate devices, while startup and smaller companies are left watching from the sidelines. Even for some of the best dancers, when it comes to predicate devices, having a good dance partner can prove to be a major key to success.

Justifying substantial equivalence for mechanical strength can be challenging in the 510(k) submission process. First, most manufacturers do not make mechanical testing results for their devices publicly available. Second, not all medical device testing standards relate directly to clinical loading; therefore, published literature cannot always be used for acceptance criteria for testing. It’s not necessarily about finding a predicate but about finding the right predicate device to meet the FDA’s expectations.

When it comes to identifying comparative testing data, there are options for the sponsors. These options include side-by-side predicate testing, leveraging an independent test lab’s historical data, or referencing the scientific publications or guidance documents by the FDA staff. The least burdensome of these options for the manufacturer is the publications and guidance documents from FDA.

FDA has recently published performance criteria for safety and performance-based pathway guidance documents, which include acceptance criteria for some limited devices such as: spinal plating systems, fracture fixation plates, non-spinal metallic bone screws, cutaneous electrodes for recording purposes, foley catheters, and dental. Although failure to achieve the minimum testing results in these guidance documents does not necessarily mean an immediate non-substantially equivalent decision, it does mean further testing and/or justification is required. Additionally, these guidance documents are only applicable to a small field of devices with specific technical characteristics.

More recently, FDA staff has published papers with summaries of mechanical testing data collected from 510(k) submissions. To date, FDA has published three of these papers:

• Mechanical performance of cervical intervertebral body fusion devices: A systematic analysis of data submitted to the Food and Drug Administration (2017)
• Mechanical performance of lumbar intervertebral body fusion devices: An analysis of data submitted to the Food and Drug Administration (2018)
• Mechanical performance of thoracolumbosacral pedicle screw systems: An analysis of data submitted to the Food and Drug Administration (2021)

Each of these publications details the test methods specific to the implant along with a table of results broken down into different percentiles. This allows sponsors to compare their own testing results to the published data and confirm substantial equivalence for mechanical strength. 

Of course, there are limitations to the published papers. For example, the intervertebral device papers did not include devices manufactured from materials other than metals and polyetheretherketone (PEEK), expandable features, or cages including coatings. Such limitations leave some devices, such as those additively manufactured, unable to justify substantial equivalence by leveraging these papers.

So where are sponsors left who are seeking clearance for a device outside of those included in FDA’s documents? Frantically looking for a new dance partner before the next song drops. 

They grab an experienced independent testing lab off the wall and spin them onto the dance floor. Involving an independent test lab who has tested devices similar to the subject sounds like a straightforward, cost-effective option, right? Not quite. 

When using an independent testing lab’s historical data, it is not as easy as the lab identifying a device they have tested in the past and comparing results. Some of the devices tested in the lab are never submitted for a 510(k) or have additional rounds of testing conducted that end up being submitted to FDA, such that a single test report identified for a particular predicate device might not represent the data the FDA has in its 510(k) submission. 

Other times, there are modifications to testing setup or deviations from the testing standard that would make a comparison less ideal and impracticable. Confirmation is needed to ensure the device has similar technical characteristics to the subject and is linked to a premarket 510(k) submission number. It is not always a guarantee that the lab can find a predicate, with similar characteristics, tied to a premarket submission that is equivalent to or worse than the subject. 

The next option is usually side-by-side predicate testing. Cost is one downside of this course of action because the sponsor is responsible not only for the inconvenience and cost of obtaining the predicate devices themselves, but also the cost of the mechanical testing for both sets of devices. Many of the medical devices requiring mechanical testing are not available on the shelf at the local store and instead are available by prescription only. 

Acquiring these devices can come down to who is prepared to beg, borrow, and steal. For many small companies, obtaining physical predicate devices is a time and resource intensive process that can undermine bringing new devices to the market. 

The goal of the medical device industry continues to be creating new, innovative technologies to better the lives of patients and medical professionals. Many times, in order to achieve this goal, subject devices include technological characteristics, materials, or mechanisms of operation that do not directly pair back to a large predicate population. When trying to identify a comparison for mechanical testing data, this can become even more burdensome when the subject device is unique in one or more technical characteristics as this causes the scope of acceptable predicates to shrink. Sponsors may become limited to a narrow field of options to test against, causing a more difficult road to show substantial equivalence. Snatching up an experienced dance partner (i.e., regulatory consultant) can lead to additional ways to show substantial equivalence for these more unique devices. Having the right partner is critical.

The FDA continues to do its part in reducing the burden on medical device manufacturers by providing mechanical testing data summaries to be leveraged in 510(k) submissions. For the devices that fall within these boundaries, the dance floor seems inviting. For other devices, the hill to gain substantial equivalence is much more daunting. In a perfect world, the FDA would continue to publish data summaries for more device types, sending manufacturers cheering in the streets. 

However, as changes continue to occur at the FDA, there is much uncertainty surrounding any future publications or guidance documents like those discussed. While the pathway to substantial equivalence is straightforward for some, more and more devices require a bit of a dance to earn that final clearance. Knowing how to dance sometimes isn’t enough—you’ve got to find the right partner.

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Hannah Taggart is a forward-thinking biomedical engineer and regulatory specialist with Empirical Technologies who is helping to navigate clients through the complex regulatory landscape to provide innovative and compliant medical devices for their patients.