The GMK knee prosthesis is designed for cemented use in total knee arthroplasty, if there is evidence of sufficient sound bone to seat and support the components. This knee replacement system is indicated in the following cases: Severely painful and/or disabled joint as a result of arthritis, traumatic arthritis, rheumatoid arthritis or polyarthritis. Avascular necrosis of femoral condyle. Post traumatic loss of joint configuration. Primary implantation failure. Tibial augments are to be attached to the tibial baseplate with both the fixing cylinders and bone cement. In case a semi-constrained liner is used, an extension stem must be implanted both on the tibial and on the femoral components.

Device Description

The GMK Short Stem is a tibial extension stem made of titanium alloy (Ti6-Al4-V) according to ISO5832-3:1996, Implants for Surgery - Metallic materials - Part 3: Wrought titanium 6-aluminum 4-vanadium alloy. The GMK Short Stem has a diameter of 11mm and a length of 30mm. The GMK Short Stem is compatible with the tibial baseplates of the GMK Total Knee System (K090988) and the tibial baseplates of the GMK Sphere Total Knee System (K121416).

AI/ML Overview

This document describes a 510(k) premarket notification for the "GMK Short Stem," a tibial extension stem for total knee arthroplasty. The submission focuses on demonstrating substantial equivalence to predicate devices, primarily through mechanical performance data and comparison of specifications, rather than a clinical study involving human patients or complex AI algorithms that would require extensive acceptance criteria tables and detailed study designs.

Therefore, many of the requested categories (2-9) regarding acceptance criteria for AI/diagnostic devices, sample sizes, expert ground truth, MRMC studies, standalone performance, and training sets are not applicable to this type of submission.

Here's a breakdown of the requested information based on the provided text:

1. A table of acceptance criteria and the reported device performance

Acceptance Criteria Category	Specific Criteria	Reported Device Performance
Mechanical Performance	General: Capable of withstanding expected in vivo loading without failure. Specific (implicitly): Equivalence regarding materials, diameter, and morse taper to the 65mm GMK tibial extension stem (K090988). Specific (implicitly): Modular connection to the tibial baseplate equivalent to the connection of the GMK tibial baseplate (K090988). Risk Analysis Outcome: No new significant risks identified compared to predicate, and not a "worst case" scenario in terms of modular connection to the tibial baseplate when compared to K090988.	The mechanical data indicates that the GMK Short Stem "is equivalent to devices currently cleared for use and is capable of withstanding expected in vivo loading without failure." It has "the same specifications (materials, diameter, and morse taper) as the 65mm GMK tibial extension stem cleared under K090988." "Since the modular connection to the GMK tibial baseplate (K090988) is the same, the test performed on the tibial modular connection (K090988) is also applicable to the connection when the GMK Short Stem is used and no further tests are needed to prove substantial equivalence." Risk analysis identified no new risks, and the GMK Short Stem was determined "not worst case" compared to the K090988 GMK Total Knee component's modular connection. Conclusion: Based on this, the device is considered substantially equivalent to its predicate devices.
Material Composition	Made of titanium alloy (Ti6-Al4-V) according to ISO5832-3:1996.	"Made of titanium alloy (Ti6-Al4-V) according to ISO5832-3:1996, Implants for Surgery - Metallic materials - Part 3: Wrought titanium 6-aluminum 4-vanadium alloy."
Design Features	Diameter of 11mm and a length of 30mm. Compatible with GMK Total Knee System (K090988) and GMK Sphere Total Knee System (K121416) tibial baseplates.	"The GMK Short Stem has a diameter of 11mm and a length of 30mm." "The GMK Short Stem is compatible with the tibial baseplates of the GMK Total Knee System (K090988) and the tibial baseplates of the GMK Sphere Total Knee System (K121416)."
Indications for Use	Must be substantially equivalent to predicate devices.	The indications for use are stated as being for "cemented use in total knee arthroplasty" for conditions like arthritis, avascular necrosis, post-traumatic loss of joint configuration, and primary implantation failure. These are implicitly considered substantially equivalent to predicate devices, as stated in the "Comparison to Predicate Devices" section: "The indications for use, design features and materials of the GMK Short Stem are substantially equivalent to those of the predicate devices."

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

Not Applicable. This submission relies on mechanical testing of medical device components and comparative analysis of specifications, not on clinical data (human patient data) that would involve a "test set" in the context of AI or diagnostic devices. The performance testing mentions "design verification was conducted to written protocols with pre-defined acceptance criteria," which implies lab-based mechanical testing of prototypes or manufacturing samples.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

Not Applicable. Ground truth, in the context of expert consensus or clinical outcomes, is not relevant for this type of mechanical device submission. Acceptance criteria were based on "standards, FDA guidance, and comparison to the predicate device system," which are engineering and regulatory benchmarks, not expert clinical interpretation.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

Not Applicable. There was no expert adjudication process for a "test set" in the clinical sense.

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

Not Applicable. This is a hardware component (a tibial extension stem) for knee arthroplasty, not an AI or imaging diagnostic device.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

Not Applicable. This is a hardware component, not an algorithm.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)

The "ground truth" or basis for evaluation of this device is primarily mechanical engineering standards (e.g., ISO5832-3:1996), FDA guidance documents, and direct comparison of design specifications and materials to previously cleared predicate devices.

8. The sample size for the training set

Not Applicable. This is a mechanical device, not an AI model requiring a training set.

9. How the ground truth for the training set was established

Not Applicable. See above.

Summary

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K133630

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510(k) Summary

Applicant/Sponsor: Medacta International SA Strada Regina 6874 Castel San Pietro (CH) Switzerland Phone (+41) 91 696 60 60 Fax (+41) 91 696 60 66

Contact Person: Adam Gross Director of Regulatory, Quality and Compliance Medacta USA 4725 Calle Quetzal, Unit B Camarillo, CA, 93012 Phone: (805) 322-3289 Fax: (805) 437-7553 Email: AGross@medacta.us.com

November 22, 2013 Date Prepared:

DEVICE INFORMATION

Trade/Proprietary Name: GMK Short Stem Common Name: Total Knee Prosthesis Classification Name: Knee joint patellofemorotibial polymer/metal/polymer semiconstrained cemented prosthesis 21 CFR 888.3560 Class II Device Product Codes: JWH

Predicate Devices:

510(k)	Product	510(k) Holder	Clearance Date
K090988	GMK Total Knee System	Medacta International	7/10/2009
K121416	GMK Sphere	Medacta International	7/30/2012
K043101	NexGen	Zimmer	3/7/2005

GMK Short Stem 510(k)

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Product Description

Indications for Use

The GMK knee prosthesis is designed for cemented use in total knee arthroplasty, if there is evidence of sufficient sound bone to seat and support the components.

This knee replacement system is indicated in the following cases:

· Severely painful and/or disabled joint as a result of arthritis, traumatic arthritis, rheumatoid arthritis or polyarthritis.

· Avascular necrosis of femoral condyle.
· Post traumatic loss of joint configuration.
· Primary implantation failure.

Tibial augments are to be attached to the tibial baseplate with both the fixing cylinders and bone cement.

In case a semi-constrained liner is used, an extension stem must be implanted both on the tibial and on the femoral components.

Comparison to Predicate Devices

The indications for use, design features and materials of the GMK Short Stem are substantially equivalent to those of the predicate devices. The GMK Short Stem has the same materials, diameter, and morse taper as the GMK 65mm tibial extension stem cleared under K090988 and has a similar length as the tibial extension stem cleared under the Zimmer NexGen predicate device. The safety and effectiveness of the GMK Short Stem are adequately supported by the substantial equivalence information, materials information, and analysis data provided within this Premarket Notification.

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Performance Testing

A review of the mechanical data indicates that the GMK Short Stem is equivalent to devices currently cleared for use and is capable of withstanding expected in vivo loading without failure. The GMK Short Stem has the same specifications (materials, diameter, and morse taper) as the 65mm GMK tibial extension stem cleared under K090988. Since the modular connection to the GMK tibial baseplate (K090988) is the same, the test performed on the tibial modular connection (K090988) is also applicable to the connection when the GMK Short Stem is used and no further tests are needed to prove substantial equivalence.

The modification to the device system to include the addition of the GMK Short Stem was evaluated by risk analysis to identify any new risks associated with the change. Based on the risk analysis, design verification was conducted to written protocols with pre-defined acceptance criteria. The protocols and pre-defined acceptance criteria were based on the standards, FDA guidance, and comparison to the predicate device system. The GMK Short Stem was compared to the worst case K090988 GMK Total Knee component in terms of modular connection to the tibial baseplate and it was determined that the GMK Short Stem is not worst case.

Conclusion:

Based on the above information, the GMK Short Stem can be considered as substantially equivalent to its predicate devices.

GMK Short Stem 510(k)

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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002

December 20, 2013

Medacta International SA % Mr. Adam Gross Director of Regulatory, Quality and Compliance 4725 Calle Quetzal, Unit B Camarillo, California 93012

Re: K133630

Trade/Device Name: GMK Short Stem ·············································································································································································· Regulation Name: Knee joint patellofemorotibial polymer/metal/polymer semi-constrained cemented prosthesis Regulatory Class: Class II Product Code: JWH Dated: November 22, 2013 Received: November 26, 2013

Dear Mr. Gross:

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 (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. The general controls provisions of the Act include requirements for annual registration. Iisting 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.

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 803); good manufacturing practice requirements as set

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Page 2 - Mr. Adam Gross

forth in the quality systems (OS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Division of Small Manufacturers, International and Consumer Assistance at its tollfree number (800) 638-2041 or (301) 796-7100 or at its Internet address http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm. Also, please note the requlation entitled. "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21

CFR Part 803), please go to

http://www.fda.gov/MedicalDevices/Safety/ReportalProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.

You may obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address http://www.fda.gov/MedicalDevices/Resourcesfor You/Industry/default.htm.

Sincerely yours.

Ronald-P: Jean -S for

Mark N. Melkerson Director Division of Orthopedic Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known): K133630

Device Name: GMK Short Stem

Indications for Use: ·

The GMK knee prosthesis is designed for cemented use in total knee arthroplasty, if there is evidence of sufficient sound bone to seat and support the components.

This knee replacement system is indicated in the following cases:

· Severely painful and/or disabled joint as a result of arthritis, traumatic arthritis, rheumatoid arthritis or polyarthritis.

· Avascular necrosis of femoral condyle.
Post traumatic loss of joint configuration.
· Primary implantation failure.

Tibial augments are to be attached to the tibial baseplate with both the fixing cylinders and bone cement.

In case a semi-constrained liner is used, an extension stem must be implanted both on the tibial and on the femoral components.

Prescription Use × (21 CFR 801 Subpart D)

AND/OR

Over-The-Counter Use (21 CFR 801 Subpart C)

(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE IF NEEDED) Concurrence of CDRH, Office of Device Evaluation (ODE)

Elizabeth 👍Frank -S

Division of Orthopedic Devices

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.