510(k) vs De Novo: Which FDA Pathway Fits a Novel Surgical Robot?

If a legally marketed predicate device exists, a surgical robot generally goes through a 510(k), which must reach FDA at least 90 days before commercial distribution and must show substantial equivalence. If there is no predicate, but general controls (or general and special controls) can still give reasonable assurance of safety and effectiveness, the De Novo classification process applies, and FDA must decide by written order within 120 days of receipt. Everything below comes from the FDA documents indexed in our FDA surgical robotics and SaMD knowledge base; it explains the rules and is not regulatory advice for your specific device.

The deciding question: is there a predicate?

FDA's guidance The 510(k) Program: Evaluating Substantial Equivalence in Premarket Notifications (issued July 28, 2014) states that a manufacturer “must submit a 510(k) to FDA at least 90 days before introducing, or delivering for introduction, a device into interstate commerce for commercial distribution”, unless the device is exempt. FDA's decision rests on whether the new device is substantially equivalent (SE) to a legally marketed predicate.

A predicate, under 21 CFR 807.92(a)(3) as quoted in that guidance, is a device legally marketed before May 28, 1976, a device reclassified from class III to class II or I, or a device found substantially equivalent through the 510(k) process. If nothing fits, the logic of the statute kicks in: a new post-amendments device is automatically in class III under section 513(f)(1) of the FD&C Act, and an NSE (not substantially equivalent) determination also places the device in class III. That is the problem De Novo was created to solve.

The 510(k) route for a surgical robot

The 510(k) review standard is comparative. The guidance contrasts it with the PMA standard, which “relies on an independent demonstration of safety and effectiveness”. It also notes that a new device does not need to be identical to its predicate, and that the evidence needed grows as the differences grow, when those differences significantly affect, or may significantly affect, safety or effectiveness.

For robots specifically, FDA published the draft guidance Robotically-Assisted Surgical Devices: Premarket Submissions on September 25, 2026. It is a draft, distributed for comment and marked “Not for Implementation”, so it is not yet FDA's final position. For 510(k)s, the draft asks you to:

• identify the classification regulation number and product code of your device based on the proposed predicate;
• provide a side-by-side comparison with the predicate, using “identical” or “same” only for features that are demonstrably identical (same manufacturer, design, materials, functions);
• describe every technological difference and explain why it does not affect substantial equivalence, with data showing the device is as safe and effective and raises no different questions;
• consider a supplementary table summarizing new or altered features, their impact and where the supporting test reports sit in the submission;
• list any reference devices used alongside the predicate.

One trap worth knowing: the base indexes 21 CFR 876.1500 (endoscope and accessories), but that regulation's text never uses the words “robotic” or “computer-controlled”. It defines the device generically as one used “to provide access, illumination, and allow observation or manipulation of body cavities, hollow organs, and canals”. Do not infer your robot's classification from the regulation text alone; the draft RASD guidance points to the predicate's regulation and product code, and to the Q-Submission Program if you are unsure.

The De Novo route when no predicate exists

FDA's guidance De Novo Classification Process (Evaluation of Automatic Class III Designation), issued October 5, 2021, describes De Novo as “a pathway to class I or class II classification for medical devices for which general controls or general and special controls provide a reasonable assurance of safety and effectiveness, but for which there is no legally marketed predicate device” (section 513(f)(2) of the FD&C Act).

You can file a Direct De Novo without a prior 510(k) if you determine there is no predicate, or file after an NSE determination. After a 510(k), FDA will consider a De Novo when the NSE was due to (1) lack of an identifiable predicate, (2) a new intended use, or (3) different technological characteristics raising different questions. A device found NSE solely because of inadequate performance data would generally be ineligible.

The De Novo clock, step by step

1. Pre-Submission (optional, strongly recommended): FDA's preliminary view on eligibility, likely controls and the evidence needed. The guidance suggests including your proposed class, your database searches and a rationale for why no existing regulation or product code fits.
2. Acceptance review: FDA notifies you within 15 calendar days whether the request is accepted (21 CFR 860.230). If it misses that window, the request is accepted.
3. Substantive review: FDA checks whether a likely predicate exists or a class III regulation applies. If so, the request is declined.
4. Additional information: an AI letter stops the clock; no complete response within 180 calendar days and the request is considered withdrawn.
5. Decision: a written order within 120 days of receipt. A grant allows immediate marketing, creates a classification regulation and lets the device serve as a predicate. FDA then publishes a final order in the Federal Register within 30 days.

If the request is declined, the device remains in class III and may not be legally marketed. The guidance lists the ways forward: a PMA application, or a new De Novo request with additional information. The De Novo request also needs at least one valid eCopy, or the review clock will not start.

510(k) vs De Novo at a glance

Where PMA fits, and what the base does not tell you

The base covers PMA only indirectly: it contrasts the comparative 510(k) standard with the PMA's independent demonstration, names PMA as the route after a declined De Novo, and mentions that PMA applications must include proposed labeling (in the RASD draft). It contains no PMA guidance, so it cannot answer questions such as the exact PMA review timeline or the fee schedule. Check FDA's PMA resources directly for those.

Two other points matter early in planning. First, the RASD draft says that for new RASDs (never authorized in the U.S.), clinical data are often needed, and that FDA generally considers investigational RASDs to be significant risk devices under the IDE regulation (21 CFR Part 812). Second, if your robot carries AI features you plan to update, a Predetermined Change Control Plan can be established through a 510(k), a De Novo request or a PMA, according to FDA's final PCCP guidance.

A practical checklist before you pick a pathway

• Search FDA's public databases and document your search terms. The De Novo guidance expects this, and it also exposes possible predicates.
• Write your intended use and indications precisely. A different intended use alone can make a device NSE.
• Map every technological difference from the closest candidate predicate (materials, design, energy source, control architecture) and ask whether it raises different questions of safety and effectiveness.
• List each risk to health with its proposed mitigation, separating general from special controls (needed for a De Novo).
• Check whether your robot is even a RASD under the draft definition. Pre-operative planning and stereotaxic systems are not RASDs and are outside its scope.
• Plan a Pre-Submission: strongly recommended for De Novo, and the draft RASD guidance points there whenever you are unsure.

You can test these questions against the source texts. For example, ask the base “Our device has no similar product already cleared by FDA; what's our regulatory path?” and you get an answer citing the De Novo guidance, with the passage it relies on.

Primary sources: The 510(k) Program guidance, De Novo Classification Process guidance and the draft RASD premarket guidance. Confirm the current versions on fda.gov before you file anything.