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G.K.S. PRIME FLEX CR is indicated for use in patients with severely painful and disabled joints due to:

• Osteoarthritis, traumatic arthritis, rheumatoid arthritis or polyarthritis .
• Failed osteotomies
• Avascular necrosis of femoral condyle .
• Post traumatic loss of joint configuration
• Moderate varus, valgus or flexion deformity in which the ligamentous structures can be returned to adequate function and stability
• Primary implantation failure if there is sufficient bone .

The device is intended for cemented use only.

The GKS Prime Flex CR Total Knee System is a tricompartmental fixed bearing total knee prosthesis comprised of femoral, patellar, and tibial components with ultra-high molecular weight polyethylene articular inserts. The femoral components are offered in left and right versions in eight sizes each. The tibial baseplate components are offered in seven sizes offered in two styles: Universal which will work with either left or right knees and Anatomic which provides components anatomically shaped for left and right knees. The keel has a cylindrical body with two stabilizing wings and allows for future use of extension stems. The tibial inserts fit into the tibial baseplates by a snap-in mechanism. The cruciate retaining tibial inserts are offered in seven sizes, each size in four thicknesses from 10 mm to 18 mm. These tibial inserts work with the universal design or either the left or right anatomic version. The patella is offered in four sizes from 32 to 38 mm. The devices are for cemented use only.

The bone opposing surfaces are not coated but have their surfaces roughened by sand blasting.

The tibial baseplates come with threaded plugs for bone screw holes as no bone screws are available with this system. A distal plug for a future extension stem is also provided.

The GKS Prime Flex CR Total Knee System femoral components are made of Cobalt Chromium Molybdenum (CoCrMo) according to ISO 5832-4. Tibial baseplate components, threaded plugs for screw holes, and distal plug are made of titanium alloy (Ti6-Al4-V) according to ISO 5832-3. Tibial inserts and patellar components are made of standard ultra-high molecular weight polyethylene (UHMWPE) according to ISO 5834-1/2.

Here's a breakdown of the acceptance criteria and study information based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

• Femoral components: Cobalt Chromium Molybdenum (CoCrMo) according to ISO 5832-4.
• Tibial baseplate components, threaded plugs, distal plug: Titanium alloy (Ti6-Al4-V) according to ISO 5832-3.
• Tibial inserts and patellar comp: UHMWPE according to ISO 5834-1/2. | The GKS Prime Flex CR Total Knee System components are made of the specified materials, conforming to the respective ISO standards. |
  | Functional Testing (Nonclinical) | Acceptance criteria were pre-defined and based on applicable standards and FDA guidance documents (specifically: "Class II Special Controls Guidance Document: Knee Joint Patellofemorotibial Metal/Polymer Porous Coated Uncemented Prostheses: Guidance for Industry and FDA"). This included: | "The testing met all acceptance criteria and verifies that performance of the GKS Prime Flex CR Total Knee System is substantially equivalent to the predicate devices." (Detailed results for each test are not provided.) |
  | - Fatigue testing of the tibial base plate | (Specific quantitative criteria not explicitly detailed in the summary, but implied by adherence to guidance and overall acceptance.) | Conducted; criteria met. |
  | - Constraint and contact pressure of patella-femoral and femoro-tibial interfaces | (Specific quantitative criteria not explicitly detailed.) | Conducted; criteria met. |
  | - Modular connections of tibial inserts to tibial baseplates | (Specific quantitative criteria not explicitly detailed.) | Conducted; criteria met. |
  | Overall Performance (Substantial Equivalence) | The device must demonstrate substantial equivalence to predicate devices with respect to indications for use and technological characteristics. | "The data and information provided in this submission support the conclusion that the GKS Prime Flex CR Total Knee System is substantially equivalent to its predicate devices with respect to indications for use and technological characteristics." |

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

• Sample Size for Test Set: The document states that testing was conducted on "the worst case component size and option/design." No specific numerical sample size (e.g., number of units tested, number of cycles for fatigue) is provided.
• Data Provenance: The testing was nonclinical (laboratory-based performance testing). The document does not specify a country of origin for the data beyond Permedica SpA being an Italian manufacturer, but indicates the testing was conducted in accordance with FDA guidance documents. It is retrospective in the sense that the testing was performed and then summarized for the submission.

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

This information is not applicable as the study described is a nonclinical, performance-based study on a medical device (knee replacement system), not a study involving human interpretation or diagnosis where "ground truth" would be established by experts.

4. Adjudication Method for the Test Set

This information is not applicable as the study is a nonclinical, performance-based study, not one requiring adjudication of human assessments.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, and its effect size

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. The document explicitly states: "Clinical data and conclusions are not needed for this device." The study was nonclinical performance testing.

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

This information is not applicable. The device is a physical medical implant (a total knee system), not an algorithm or AI system. Therefore, the concept of "standalone performance" for an algorithm does not apply. The performance testing described is inherently "standalone" in the sense that it's the device itself being tested in a controlled, non-human environment.

7. The type of ground truth used

The "ground truth" for this nonclinical performance study was established by pre-defined acceptance criteria based on applicable standards and guidance documents (e.g., ISO standards, FDA guidance for knee prostheses). This includes expectations for material properties and specific functional performance metrics (fatigue, constraint, contact pressure, modular connection integrity).

8. The sample size for the training set

This information is not applicable. As a physical medical device, there is no "training set" in the context of machine learning or AI models. The device's design is developed through engineering and manufacturing processes, not trained on data.

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

This information is not applicable for the same reason as point 8.

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