The EARP Nerve Cuff Electrode is used to perform localized stimulation of neural tissue and to locate, identify, and monitor spinal nerve roots during surgery.
Device Story
The EARP Nerve Cuff Electrode is a single-use, sterile, bipolar nerve cuff electrode used during surgery for intraoperative neuromonitoring. It acts as a passive conduit for electrical signals between external, commercially available neuromonitoring equipment and target spinal nerve roots. The device features a C-shaped silicone cuff that engages the nerve directly; platinum electrode contacts; and stainless steel lead wires. It does not generate or record signals independently. Surgeons use the device to facilitate nerve identification and monitoring; the output is displayed on the connected neuromonitoring system to assist in clinical decision-making during spinal procedures. The device is removed after the surgical procedure.
Clinical Evidence
No clinical data. Substantial equivalence is supported by non-clinical analysis of design modifications.
Indicated for patients undergoing surgery requiring localization, identification, and monitoring of spinal nerve roots via localized neural tissue stimulation.
Regulatory Classification
Identification
A surgical nerve stimulator/locator is a device that is intended to provide electrical stimulation to the body to locate and identify nerves and to test their excitability.
{0}
FDA U.S. FOOD & DRUG ADMINISTRATION
July 31, 2024
Retropsoas Technologies, LLC
% Jeffrey Brittan
Vice President of Product Realization
Watershed Idea Foundry, Inc. (dba SpiTrex 3D)
1815 Aston Avenue, Suite 106
Carlsbad, California 92008
Re: K241917
Trade/Device Name: EARP Nerve Cuff Electrode
Regulation Number: 21 CFR 874.1820
Regulation Name: Surgical Nerve Stimulator/Locator
Regulatory Class: Class II
Product Code: ETN
Dated: June 28, 2024
Received: July 1, 2024
Dear Jeffrey Brittan:
We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).
U.S. Food & Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993
www.fda.gov
{1}
K241917 - Jeffrey Brittan
Page 2
Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90, Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review, the QS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).
Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting (reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reporting-combination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.
Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-devices/medical-device-safety/medical-device-reporting-mdr-how-report-medical-device-problems.
For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).
Sincerely,
Jay R. Gupta -S
Jay Gupta
Assistant Director
DHT5A: Division of Neurosurgical, Neurointerventional and Neurodiagnostic Devices
OHT5: Office of Neurological and Physical Medicine Devices
Office of Product Evaluation and Quality
Center for Devices and Radiological Health
{2}
K241917 - Jeffrey Brittan
Page 3
Enclosure
{3}
FORM FDA 3881 (8/23)
Page 1 of 1
PSC Publishing Services (301) 443-6740
EF
| DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration Indications for Use | Form Approved: OMB No. 0910-0120 Expiration Date: 07/31/2026 See PRA Statement below. |
| --- | --- |
| 510(k) Number (if known) K241917 | |
| Device Name EARP Nerve Cuff Electrode | |
| Indications for Use (Describe) The EARP Nerve Cuff Electrode is used to perform localized stimulation of neural tissue and to locate, identify, and monitor spinal nerve roots during surgery. | |
| Type of Use (Select one or both, as applicable) ☑ Prescription Use (Part 21 CFR 801 Subpart D) ☐ Over-The-Counter Use (21 CFR 801 Subpart C) | |
| CONTINUE ON A SEPARATE PAGE IF NEEDED. | |
| This section applies only to requirements of the Paperwork Reduction Act of 1995. *DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.* | |
| The burden time for this collection of information is estimated to average 79 hours per response, including the time to review instructions, search existing data sources, gather and maintain the data needed and complete and review the collection of information. Send comments regarding this burden estimate or any other aspect of this information collection, including suggestions for reducing this burden, to: Department of Health and Human Services Food and Drug Administration Office of Chief Information Officer Paperwork Reduction Act (PRA) Staff PRAStaff@fda.hhs.gov | |
| "An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB number." | |
{4}
EARP Nerve Cuff Electrode
Page 1 of 3
# 510(k) Summary
## DATE PREPARED
June 27, 2024
## CONTACT DETAILS
| Applicant | Retropsoas Technologies, LLC
34 Countryside Lane
Frontenac, MO 63131 USA
Telephone: 618-402-0035
Contact: Dr. Nicholas Poulos, CEO
Email: npoulos@retropsoas.com |
| --- | --- |
| Correspondent | Jeffrey Brittan
Vice President of Product Realization
SpiTrex 3D (Watershed Idea Foundry, Inc. dba SpiTrex 3D)
Telephone: 714-287-6780
Email: jeffbrittan@spitrexorthopedics.com |
## DEVICE NAME
| Device Trade Name | EARP Nerve Cuff Electrode |
| --- | --- |
| Common Name | Surgical nerve stimulator/locator |
| Classification Name | Stimulator, Nerve |
| Regulation Number | 21 CFR 874.1820 |
| Product Code | ETN |
## LEGALLY MARKETED PREDICATE DEVICES
| Predicate # | K230853 |
| --- | --- |
| Predicate Trade Name | EARP Nerve Cuff Electrode |
| Product Code | ETN |
## DEVICE DESCRIPTION SUMMARY
The EARP Nerve Cuff Electrode conducts electrical signal as a component of intraoperative neuromonitoring. The EARP Nerve Cuff Electrode is used with commercially available neuromonitoring systems and does not stimulate or record signal itself. The standard connectors at the proximal end of the EARP Nerve Cuff Electrode interface with the neuromonitoring equipment and the distal cuff contacts the target tissue. The EARP Nerve Cuff Electrode is provided sterile packaged and is for single use only.
{5}
EARP Nerve Cuff Electrode
Page 2 of 3
# INTENDED USE / INDICATIONS FOR USE
The EARP Nerve Cuff Electrode is used to perform localized stimulation of neural tissue and to locate, identify, and monitor spinal nerve roots during surgery.
# INDICATIONS FOR USE COMPARISON
There are no changes to indications for use for the subject device in comparison to the predicate device (i.e., indications for use are the same).
# TECHNOLOGICAL COMPARISON
The subject device has been updated with "slimline" versions that maintain equivalent design characteristics, materials, chemical composition, and principle of operation as the predicate device, while offering nerve cuff options with smaller sizing. The smaller cuff inside diameter and width sizing options provide additional flexibility for physicians who may have patients with smaller anatomy or who prefer to use a smaller device without changing device function or performance. In addition, a manufacturability enhancement to use a single thickness for the nitinol spring component is included.
| | Subject Device | Predicate Device | Equiv. |
| --- | --- | --- | --- |
| | EARP Nerve Cuff Electrode (Subject Device) | EARP Nerve Cuff Electrode (K230853) | |
| Indications for Use | The EARP Nerve Cuff Electrode is used to perform localized stimulation of neural tissue and to locate, identify, and monitor spinal nerve roots during surgery. | The EARP Nerve Cuff Electrode is used to perform localized stimulation of neural tissue and to locate, identify, and monitor spinal nerve roots during surgery. | Yes |
| Principle of Operation | Conducts signal between neuromonitoring equipment and nerve (interfaces w/ commercially available neuromonitoring systems) | Conducts signal between neuromonitoring equipment and nerve (interfaces w/ commercially available neuromonitoring systems) | Yes |
| Product Codes /Reg# | ETN (21 CFR 874.1820) Stimulator, Nerve | ETN (21 CFR 874.1820) Stimulator, Nerve | Yes |
| Duration of Use | Intraoperative (Single use) | Intraoperative (Single use) | Yes |
| Implanted | No (Removed after use) | No (Removed after use) | Yes |
| Tissue Engagement | Direct nerve contact (C-shaped cuff) | Direct nerve contact (C-shaped cuff) | Yes |
| Tip Contact Exposure | 2mm (Strip) | 2mm (Strip) | Yes |
| Bipolar or Monopolar? | Bipolar | Bipolar | Yes |
| Electrode Contact Material | Conductive metal (Platinum) | Conductive metal (Platinum) | Yes |
| Electrode Insulation | Polymer (Polyimide) | Polymer (Polyimide) | Yes |
| Cuff Material | Polymer (Silicone) | Polymer (Silicone) | Yes |
| Lead Length | 1.8m | 1.8m | Yes |
| Lead Wire Material | Conductive metal (Stainless steel) | Conductive metal (Stainless steel) | Yes |
| Lead Wire Insulation | Polymer (FEP) | Polymer (FEP) | Yes |
| Connector Style | 1.5mm safety socket | 1.5mm safety socket | Yes |
| Cuff Sizing | Inside diameters: 3, 4, 5, 6mm Width: 3mm Inside diameter encircling: 90% | Inside diameters: 4, 6, 8, 10mm Width: 5mm Inside diameter encircling: 85% | Yes |
| Nitinol Spring Thickness | Circular segment: 0.19mm Horn segment: 0.19mm | Circular segment: 0.19mm Horn segment: 0.25mm | Yes |
| Provided Sterile | Yes | Yes | Yes |
{6}
EARP Nerve Cuff Electrode
Page 3 of 3
# NON-CLINICAL TESTS SUMMARY & CONCLUSIONS
Analysis of the subject device modifications verified that they would not impact function or performance. Results of this analysis demonstrated that the additional sizing options for the silicone cuff, as well as the single spring thickness manufacturability enhancement, would not affect the ability of the device to mate with the applicator tool, be applied to and maintain contact with the nerve and, or conduct neuromonitoring signal. Accordingly, the analysis supported the conclusion that the subject EARP Nerve Cuff Electrode is substantially equivalent to the predicate EARP Nerve Cuff Electrode.
Predicate graph will load when search results are available.
Embedding visualization will load when search results are available.
PDF viewer will load when search results are available.
Loading panels...
Select an item from Submissions
Click any panel, subpart, regulation, product code, or device to see details here.
Section Matches
Results will appear here.
Product Code Matches
Results will appear here.
Special Control Matches
Results will appear here.
Loading collections...
Loading
My Alerts
You will receive email notifications based on the filters and frequency you set for each alert.
Sort by:
Create Alert
Search Filters
Agent Token
Create a read-only bearer token for Claude, ChatGPT, or other agents that can call HTTP APIs.
Copy this now. It will not be shown again.
Connected apps
Apps you authorized through browser sign-in. Disconnecting revokes their access immediately.
Learn the FDA Browser
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.