The Phantom® Hindfoot TTC/TC Nail System is indicated for tibiotalocalcaneal arthrodesis (fusion) and to provide stabilization of the hindfoot and ankle including the transverse tarsal joints coupling the mid-foot to the hindfoot. Examples of specific indications include:

Post-traumatic or degenerative arthritis
Previously infected arthrosis
Revision of failed ankle arthrodesis
Revision of failed total ankle arthroplasty
Talar deficiency conditions such as avascular necrosis of the talus (requiring tibiocalcaneal arthrodesis)
Neuromuscular deformity or other neuromuscular disease with severe deformity or instability of the ankle
Rheumatoid arthritis
Osteoarthritis
Nonunions or pseudarthrosis of hindfoot and distal tibia
Trauma (severe or malunited tibial pilon fracture)
Charcot foot (neuroarthropathy)
Severe end-stage degenerative arthritis
Instability and skeletal defects after tumor resection
Pantalar arthrodesis
Severe foot/ankle deformity

Device Description

Phantom® Hindfoot TTC/TC Nail System is comprised of intramedullary nails, screws and accessory components. The subject Phantom® Hindfoot TTC Trauma Nails are offered in a variety of sizes and lengths to accommodate variations in patient anatomy. The Phantom® TTC/TC screws insert through the intramedullary nail to secure the construct. These are offered in varying lengths to accommodate the anatomical fixation required.

AI/ML Overview

I am sorry, but the provided text is a 510(k) clearance letter for a medical device (Phantom® Hindfoot TTC/TC Nail System) and does not contain the specific information you are requesting about acceptance criteria, study details, expert qualifications, or ground truth establishment for a diagnostic or AI-based device.

This document is a regulatory approval notice that states the device is substantially equivalent to a previously cleared predicate device. It confirms the device's indications for use, its classification, and mentions that "engineering analysis is presented to provide evidence that the original testing and subsequent performance is not adversely affected by the modifications to the subject devices." However, it does not elaborate on:

A specific table of acceptance criteria and reported device performance.
Sample sizes for test sets or data provenance.
Number or qualifications of experts used for ground truth.
Adjudication methods.
MRMC comparative effectiveness study results or effect sizes.
Stand-alone algorithm performance (as this is not an AI/diagnostic device).
Type of ground truth used.
Training set sample size.
How ground truth for the training set was established.

The document discusses "performance testing" and "engineering analysis" to demonstrate substantial equivalence, but it does not detail these tests in the way you've outlined for a diagnostic or AI study. The "device" in question is a surgical implant system, not a diagnostic tool or an AI algorithm that would typically have the kind of performance metrics you are seeking.

Summary

U.S. Food & Drug Administration 510(k) Clearance Letter

Page 1

U.S. Food & Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993
www.fda.gov

Doc ID # 04017.08.00

July 14, 2025

Paragon 28, Inc
Edward Wells-Spicer
Regulatory Affairs Specialist II
14445 Grasslands Drive
Englewood, Colorado 80112

Re: K251850
Trade/Device Name: Phantom® Hindfoot TTC/TC Nail System
Regulation Number: 21 CFR 888.3020
Regulation Name: Intramedullary fixation rod
Regulatory Class: Class II
Product Code: HSB, HWC
Dated: June 16, 2025
Received: June 16, 2025

Dear Edward Wells-Spicer:

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).

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K251850 - Edward Wells-Spicer
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.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

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).

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K251850 - Edward Wells-Spicer
Page 3

Sincerely,

Farzana Sharmin Digitally signed by Farzana Sharmin -S
-S Date: 2025.07.14 18:53:16 -04'00'

Farzana Sharmin, PhD
Assistant Director
DHT6A: Division of Joint Arthroplasty Devices
OHT6: Office of Orthopedic Devices
Office of Product Evaluation and Quality
Center for Devices and Radiological Health

Enclosure

Page 4

Indications for Use

Please type in the marketing application/submission number, if it is known. This textbox will be left blank for original applications/submissions. | K251850

Please provide the device trade name(s).

Phantom® Hindfoot TTC/TC Nail System

Please provide your Indications for Use below.

Post-traumatic or degenerative arthritis
Previously infected arthrosis
Revision of failed ankle arthrodesis
Revision of failed total ankle arthroplasty
Talar deficiency conditions such as avascular necrosis of the talus (requiring tibiocalcaneal arthrodesis)
Neuromuscular deformity or other neuromuscular disease with severe deformity or instability of the ankle
Rheumatoid arthritis
Osteoarthritis
Nonunions or pseudarthrosis of hindfoot and distal tibia
Trauma (severe or malunited tibial pilon fracture)
Charcot foot (neuroarthropathy)
Severe end-stage degenerative arthritis
Instability and skeletal defects after tumor resection
Pantalar arthrodesis
Severe foot/ankle deformity

Please select the types of uses (select one or both, as applicable).
☑ Prescription Use (Part 21 CFR 801 Subpart D)
☐ Over-The-Counter Use (21 CFR 801 Subpart C)

Phantom® Hindfoot TTC/TC Nail System
Page 8 of 25

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K251850 - Page 1 of 3

510(K) SUMMARY

Manufacturer: Paragon 28, Inc.
14445 Grasslands Dr.
Englewood, CO 80112

Contact: Edward Wells-Spicer
Regulatory Affairs Specialist II
Paragon 28, Inc.
14445 Grasslands Dr.
Englewood, CO 80112
Phone: 720-994-5481
Edward.WellsSpicer@zimmerbiomet.com

Date Prepared: July 14, 2025

Device Trade Names: Phantom® Hindfoot TTC/TC Nail System

Device Class: Class II

Primary Predicate(s): Phantom® Hindfoot TTC/TC Nail System (K201227)

Device Description: Phantom® Hindfoot TTC/TC Nail System is comprised of intramedullary nails, screws and accessory components. The subject Phantom® Hindfoot TTC Trauma Nails are offered in a variety of sizes and lengths to accommodate variations in patient anatomy. The Phantom® TTC/TC screws insert through the intramedullary nail to secure the construct. These are offered in varying lengths to accommodate the anatomical fixation required.

Classification and Product Codes:

21 CFR 888.3020; Rod, Fixation, Intramedullary And Accessories - HSB
21 CFR 888.3040; Screw, Fixation, Bone - HWC

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K251850 - Page 2 of 3

Indications for Use: The Phantom® Hindfoot TTC/TC Nail System is indicated for tibiotalocalcaneal arthrodesis (fusion) and to provide stabilization of the hindfoot and ankle including the transverse tarsal joints coupling the mid-foot to the hindfoot. Examples of specific indications include:

Post-traumatic or degenerative arthritis
Previously infected arthrosis
Revision of failed ankle arthrodesis
Revision of failed total ankle arthroplasty
Talar deficiency conditions such as avascular necrosis of the talus (requiring tibiocalcaneal arthrodesis)
Neuromuscular deformity or other neuromuscular disease with severe deformity or instability of the ankle
Rheumatoid arthritis
Osteoarthritis
Nonunions or pseudarthrosis of hindfoot and distal tibia
Trauma (severe or malunited tibial pilon fracture)
Charcot foot (neuroarthropathy)
Severe end-stage degenerative arthritis
Instability and skeletal defects after tumor resection
Pantalar arthrodesis
Severe foot/ankle deformity

Substantial Equivalence: The subject Phantom® Hindfoot TTC/TC Nail System and the predicate system are intended to be used for stabilization of the hindfoot and ankle. The indications for the subject device are identical to the indications of the predicate device.

The subject Phantom® Hindfoot TTC/TC Nail System components possess similar technological characteristics as the predicate device. These include:

basic design,
material, manufacturing and
sizes (dimensions are comparable to those offered by the predicate systems).

Differences in the technology of the Phantom® Hindfoot TTC Trauma Nails include longer nails and the incorporation of a clothes pin–style tip. Differences between the Phantom® Hindfoot TTC/TC Nail System implants and the predicate devices were shown not to raise new questions of safety and effectiveness. Therefore, the fundamental scientific technology of the subject Phantom® Hindfoot TTC/TC Nail System components is similar to previously cleared device.

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K251850 - Page 3 of 3

Performance Testing: Engineering analysis is presented to provide evidence that the original testing and subsequent performance is not adversely affected by the modifications to the subject devices.

The results of the analysis demonstrated the modified designs are substantially equivalent to the predicate devices.

Conclusions: The subject device Phantom® Hindfoot TTC/TC Nail System is substantially equivalent to the previously cleared predicate device Phantom® Hindfoot TTC/TC Nail System (K191782).

The subject devices possess identical indications for use, materials, design, and principles of operation as the predicates. The proposed device modifications do not raise new issues of safety or effectiveness. The subject devices are substantially equivalent to the legally marketed, predicate Phantom® Hindfoot TTC/TC Nail System.

Regulation Number and Section

§ 888.3020 Intramedullary fixation rod.

(a)
Identification. An intramedullary fixation rod is a device intended to be implanted that consists of a rod made of alloys such as cobalt-chromium-molybdenum and stainless steel. It is inserted into the medullary (bone marrow) canal of long bones for the fixation of fractures.(b)
Classification. Class II.