FEMORAL AND TIBIAL PLUGS OF INTERAX TOTAL KNEE SYSTEM by HOWMEDICA CORP.

The Interax® Total Knee System is intended to be used in cemented primary and/or revision total knee arthroplasty procedures in patients who require total knee replacement as a result of non-inflammatory joint disease and all of its variants, inflammatory joint disease, trauma, or failed previous prosthesis. The Interax® system is intended to accommodate the posterior cruciate ligament if it is intact. The collateral ligaments should be intact, or reparable, or there must be adequate capsular support to provide medio-lateral stability. The Interax® Total Knee System is intended to be implanted using bone cement.

Device Description

The Interax® femoral component and tibial baseplate previously cleared in K973121 are made available with a PMMA plug inserted onto their central stems. The purpose of this plug is to occlude the internal threaded portion of the central stem of the femoral component, and the internal taper surface of the tibial component. The PMMA plug can also be removed to allow the optional use of stem extensions. The current femoral and tibial plugs are fabricated from pellitized PMMA (Simplex P). The new femoral and tibial plugs will be made from a acrylic resin which is supplied by Rohm & Haas.

AI/ML Overview

This 510(k) summary (K980713) is a submission for an alternate material for already cleared devices (Interax® Femoral and Tibial Plugs). The acceptance criteria and supporting study in this document focus on demonstrating that the new material is substantially equivalent to the previously approved material, not a groundbreaking new device or AI algorithm. Therefore, many of the typical questions for AI/algorithm-based devices (like MRMC studies, training set details, or number of experts) are not applicable here.

Here's the relevant information based on the provided text, reinterpreting some questions to fit the context of a material change for an existing device.

1. Table of Acceptance Criteria and Reported Device Performance

Acceptance Criteria (Implicit for a Material Change)	Reported Device Performance (Implied Substantial Equivalence)
Material Equivalence: The new acrylic resin (from Rohm & Haas) for the femoral and tibial plugs is equivalent in composition and performance to the previously approved pellitized PMMA (Simplex P) material.	The 510(k) was cleared, indicating the FDA found the new material to be substantially equivalent to the predicate. The document states: "The new femoral and tibial plugs will be made from an acrylic resin which is supplied by Rohm & Haas." The lack of reported performance differences implies equivalence. No specific performance metrics (e.g., strength, durability, biocompatibility) are provided in this summary, but these would have been part of the full 510(k) submission.
No Change in Intended Use: The device (Interax® Total Knee System with the new plugs) maintains its original intended use.	The document explicitly states: "There is no change in the intended use of the femoral and tibial components of the Interax® Total Knee System..." and reiterates the established indications for use of the total knee system.
No Change in Design/Function: The plugs still occlude the internal threaded portion of the central stem/taper surface and can be removed for stem extensions.	The description of the plugs' function and purpose remains identical: "The purpose of this plug is to occlude the internal threaded portion of the central stem of the femoral component, and the internal taper surface of the tibial component. The PMMA plug can also be removed to allow the optional use of stem extensions." The material change does not alter this function.

2. Sample Size Used for the Test Set and Data Provenance

Sample Size: Not explicitly stated in this summary. For a material change, "samples" would refer to physical specimens of the new material and/or the plugs fabricated from it, subjected to various tests (e.g., mechanical, biocompatibility). The summary does not detail the number of test specimens.
Data Provenance: Not specified. It's likely that the testing (e.g., mechanical, chemical, biocompatibility) was performed in a laboratory setting, typically by the manufacturer or a contracted lab. This would be prospective testing of the new material.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

Not applicable in the context of this 510(k) for a material change. "Ground truth" in this scenario would refer to the validated properties of the new material compared to the predicate material, established through laboratory testing and engineering analysis, not expert medical opinion on pathology or images.

4. Adjudication Method for the Test Set

Not applicable. This is not a study involving human interpretation or a need for adjudication among experts regarding a test set.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance

No. This submission is for an alternate material in a medical device, not an AI or imaging diagnostic tool. Therefore, an MRMC study is not relevant.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

No. This is not an algorithm or AI-based device.

7. The Type of Ground Truth Used

Engineering/Material Comparison: The "ground truth" implicitly used for this type of submission is the established physical, chemical, and biological properties (e.g., biocompatibility) of the predicate material (pellitized PMMA Simplex P). The study would have aimed to demonstrate that the new acrylic resin from Rohm & Haas possesses equivalent characteristics, typically through:
- Material Characterization: Chemical composition, molecular weight, purity.
- Mechanical Testing: Strength, fatigue, wear resistance (if applicable to the plug's function).
- Biocompatibility Testing: According to ISO 10993 standards.
- Performance data on the finished product (the plugs) to ensure they function as intended (e.g., fit, retention).

8. The Sample Size for the Training Set

Not applicable. There is no AI algorithm involved, and thus no training set.

9. How the Ground Truth for the Training Set Was Established

Not applicable. There is no training set for an AI algorithm.

Summary

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K980713

510(k) Summary

Device: Interax® Femoral and Tibial Plugs - Alternate Material

There is no change in the intended use of the femoral and tibial components of the Interax® Total Knee System - The Interax® Total Knee System is intended to be used in cemented primary and/or revision total knee arthroplasty procedures in patients who require total knee replacement as a result of non-inflammatory joint disease and all of its variants, inflammatory joint disease, trauma, or failed previous prosthesis ... The Interax® system is intended to accommodate the posterior cruciate ligament if it is intact. The collateral ligaments should be intact, or reparable, or there must be adequate capsular support to provide medio-lateral stability. The Interax® Total Knee System is intended to be implanted using bone cement.

For information contact:

Margaret F. Crowe Manager, Regulatory Affairs Howmedica Inc. 359 Veterans Boulevard Rutherford. NJ 07070 (201) 507-7431

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Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850

MAY 22 1998

Ms. Margaret F. Crowe Group Regulatory Affairs Manager Howmedica Inc. Pfizer Hospital Products Group 359 Veterans Boulevard Rutherford, New Jersey 07070-2584

K980713 Re: Femoral and Tibial Plugs of Interax® Total Knee System Regulatory Class: II Product Code: JWH February 23, 1998 Dated: February 24, 1998 Received:

Dear Ms. Crowe:

We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to 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 (Act). You may, therefore, market the device, subject to the general controls provisions The general controls provisions of the Act of the Act. include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Requlations, Title 21, Parts 800 to 895. ਜੋ substantially equivalent determination assumes compliance with the current Good Manufacturing Practice requirement, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic (QS) inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP requlation may result in regulatory In addition, FDA may publish further announcements action. concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or requlations.

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Page 2 - Ms. Margaret F. Crowe

This letter will allow you to begin marketing your device as described in your 510 (k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4659. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to
premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsmamain.html".

Sincerely yours,

Celia M. Witten, Ph.D., M.D.

Director Division of General and Restorative Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known):

Device Name: Interax® Femoral and Tibial Plugs - Alternate material

Indications for Use:

The Interax® femoral component and tibial baseplate previously cleared in K 973121 are made available with a PMMA plug inserted onto their central stems. The purpose of this plug is to occlude the internal threaded portion of the central stem of the femoral component and the internal taper surface of the tibial component. The PMMA plug can also be removed to allow the optional use of stem extensions. The current femoral and tibial plugs are fabricated from pellitized PMMA (Simplex P). The new femoral and tibial plugs will be made from a acrylic resin which is supplied by Rohm & Haas.

There is no change in the intended use of the femoral and tibial components of the Interax® Total Knee System - The Interax® Total Knee System is intended to be used in cemented primary and/or revision total knee arthroplasty procedures in patients who require total knee replacement as a result of non-inflammatory joint disease and all of its variants, inflammatory joint disease, trauma, or failed previous prosthesis. The Interax® system is intended to accommodate the posterior cruciate ligament if it is intact. The collateral ligaments should be intact, or reparable, or there must be adequate capsular support to provide medio-lateral stability. The Interax® Total Knee System is intended to be implanted using bone cement.

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Concurrence of CDRH, Office of Device Evaluation
(Division Sign-Off)
Division of General Restorative Devices
510(k) Number	K980713
Prescription Use(Per 21 CFR 801.109)	X
OR
Over-The-Counter Use

(Optional Format 1-2-96)

Regulation Number and Section

§ 888.3560 Knee joint patellofemorotibial polymer/metal/polymer semi-constrained cemented prosthesis.

(a)
Identification. A knee joint patellofemorotibial polymer/metal/polymer semi-constrained cemented prosthesis is a device intended to be implanted to replace a knee joint. The device limits translation and rotation in one or more planes via the geometry of its articulating surfaces. It has no linkage across-the-joint. This generic type of device includes prostheses that have a femoral component made of alloys, such as cobalt-chromium-molybdenum, and a tibial component or components and a retropatellar resurfacing component made of ultra-high molecular weight polyethylene. This generic type of device is limited to those prostheses intended for use with bone cement (§ 888.3027).(b)
Classification. Class II.