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The XN Knee Prosthesis System is a knee implant developed by Beijing Chunlizhengda Medical Instruments Co. Ltd. The subject system includes femoral condyle, tibial tray, tibial insert and patella. The fixation method of the system is bone cement fixation. It is mainly used in total knee replacement to repair the diseased or injured knee joint, improve the range of motion of the knee joint and reduce the pain of the patient. The XN Knee Prosthesis System is a Posterior Stabilized (PS) total knee replacement system.

AI/ML Overview

This document is a 510(k) clearance letter from the FDA for a medical device (XN Knee Prosthesis System). It confirms that the device is substantially equivalent to a previously marketed predicate device. For devices seeking 510(k) clearance based on substantial equivalence, the "study that proves the device meets the acceptance criteria" is typically a series of non-clinical performance tests and engineering analyses that demonstrate the new device performs as safely and effectively as a legally marketed predicate device.

It's important to understand that a 510(k) submission generally does not involve large-scale clinical trials or studies akin to those for drug approvals. Instead, the focus is on demonstrating equivalence through comparison to an existing device, primarily via bench testing, material characterization, and engineering simulations.

Based on the provided text, here's a breakdown of the "acceptance criteria" and the "study" (non-clinical testing) that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The document states: "Testing and engineering analyses showed that the subject components met the pre-determined acceptance criteria identified in the Bench Testing Summary, demonstrating that the subject components are substantially equivalent compared to the predicate components."

While explicit numerical acceptance criteria for each test are not detailed in this summary (they would be in the full submission, which is not provided), the document lists the types of performance tests conducted. The "reported device performance" is implicitly that the device passed these tests and was found substantially equivalent.

Acceptance Criterion (Implied)	Reported Device Performance
Sufficient Component Interlocking Strength	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable Fatigue Performance Under High Flexion	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable Tibial Insert Constraint	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable Surface Roughness	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable Patella Contact Pressure	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable Patella Constraint	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable Static Contact Stress	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable Dynamic Fatigue	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable Wear Performance	Met acceptance criteria (demonstrated acceptable mechanical performance)
Acceptable UHMWPE Characterization	Met acceptance criteria (demonstrated acceptable mechanical performance)
Mechanical performance for intended use	Acceptable mechanical performance demonstrated for intended use
Equivalence to predicate device in intended use, materials, and fundamental technology	Substantially equivalent to predicate device

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

Sample Size: The document does not specify exact sample sizes for each test. For non-clinical bench testing, sample sizes are typically determined by relevant ASTM or ISO standards for testing medical devices (e.g., often N=3 or N=5 for certain mechanical tests, depending on variability and statistical power needs). This information would be in the detailed test protocols within the full 510(k) submission.
Data Provenance: The testing was non-clinical (bench testing and engineering analysis) and performed by the manufacturer, Beijing Chunlizhengda Medical Instruments Co. LTD. The location of primary testing would likely be China, where the manufacturer is based. It is retrospective in the sense that the data was collected and analyzed for this specific submission.

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

This question is not applicable in the context of a 510(k) non-clinical bench testing submission. "Ground truth" for these tests is established by engineering specifications, accepted industry standards (e.g., ISO, ASTM), and comparison to the predicate device's known performance characteristics. There are no human "experts" establishing a "ground truth" for each individual test sample in the way a clinical trial might use radiologists for image interpretation. The expertise lies in the engineers performing and reviewing the tests, and the FDA reviewers assessing the data against regulatory standards.

4. Adjudication Method for the Test Set

This question is not applicable as the "test set" consists of physical devices undergoing mechanical and material property testing, not subjective human assessments that would require adjudication.

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

This question is not applicable. The XN Knee Prosthesis System is a mechanical orthopedic implant, not an AI/software device used for diagnostic imaging or a human-in-the-loop system. The clearance is based on substantial equivalence to a predicate device through non-clinical performance data.

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

This question is not applicable. As stated, this is a mechanical implant, not an algorithm.

7. The Type of Ground Truth Used

For this device, the "ground truth" for substantial equivalence is primarily established through:
- Engineering specifications and design requirements: The device must meet predefined mechanical and material properties that ensure safety and efficacy.
- Comparison to the predicate device: The new device's performance is measured against the known and accepted performance of the legally marketed predicate device (Stryker Triathlon® Total Knee System). The standard is "substantially equivalent," meaning it performs as safely and effectively as the predicate.
- Relevant industry standards (e.g., ISO, ASTM): These standards often define the specific tests and acceptable ranges for performance for orthopedic implants.

8. The Sample Size for the Training Set

This question is not applicable. This is a mechanical device, not a machine learning or AI model that requires a "training set" of data.

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

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

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K Number

K202740

Device Name

Klassic Knee System Tibial Inserts, PS-Max

Manufacturer

Total Joint Orthopedics, Inc.

Date Cleared

2020-10-09

(21 days)

Product Code

Regulation Number

Type

Panel

Reference & Predicate Devices

K112906,K183596

Intended Use

The Klassic® Knee System is intended for prosthetic replacement of the following:

· Patient conditions of non-inflammatory degenerative joint disease (NIDID): avascular necrosis and osteoarthritis
Patient conditions of inflammatory joint disease (IJD): rheumatoid arthritis
· Patients with failed previous surgery where pain, deformity, or dysfunction persists
Correctable varus-valgus deformity and moderate flexion contracture
· Revision of a previously failed knee arthroplasty
· Patients who require a total knee replacement

The Klassic® Knee System is indicated for cemented use only, except for the Klassic® Femur with Cobalt 3D®, and the Klassic® Tibial Baseplate with Ti-Coat® which are indicated for cementless use.

Device Description

The purpose of this Special 510(k) is to add the Klassic® Tibial Inserts, PS-Max®, an additional posterior stabilizing design option, to the Klassic® Knee System (K112906). The Klassic® Tibial Inserts, PS-Max® are available in various sizes and thicknesses to match patient anatomy and provide surgical options.

AI/ML Overview

This submission describes the Klassic® Knee System Tibial Inserts, PS-Max®, a medical device intended for prosthetic replacement in knee arthroplasty. The submission is a Special 510(k), meaning it aims to add a new design option to an already cleared Klassic® Knee System (K112906). The primary goal is to demonstrate substantial equivalence to a predicate device, the Klassic® Tibial Inserts, PS-Post™ (K183596).

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

1. Table of Acceptance Criteria and Reported Device Performance

The document states that the subject device met pre-determined acceptance criteria for various verification activities. However, it does not explicitly list the quantitative acceptance criteria or the specific reported device performance values in a table format within the provided text. It generally states that the device "met the pre-determined acceptance criteria" and that "the results of analysis and testing indicate that the subject tibial inserts are substantially equivalent to the predicate components."

The types of tests performed indicate the areas for which performance criteria would have been established:

Acceptance Criteria Category	Reported Device Performance
Femoral/Tibial Stability Characteristics	Indicated to be substantially equivalent to the predicate. (Specific values not provided)
Contact Stress Evaluation	Indicated to be substantially equivalent to the predicate. (Specific values not provided)
Range of Motion	Indicated to be substantially equivalent to the predicate. (Specific values not provided)
Knee Simulator Wear	Indicated to be substantially equivalent to the predicate. (Specific values not provided)
Tibial Insert Post Strength and Fatigue	Indicated to be substantially equivalent to the predicate. (Specific values not provided)
Tibial Insert Modular Disassembly	Indicated to be substantially equivalent to the predicate. (Specific values not provided)
Compliance with LAL requirements for orthopedic implants	"in compliance with LAL requirements for orthopedic implants."

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

The document does not provide details on the sample size used for the test set or the data provenance. It only mentions "Bench testing and engineering analysis were performed." This implies laboratory-based testing rather than clinical data from human subjects.

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

Not applicable. The study appears to be engineering and bench testing, not involving human expert assessment of a test set for ground truth establishment.

4. Adjudication Method for the Test Set

Not applicable. The study focused on bench testing, which doesn't typically involve adjudication in the clinical sense.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No. The document describes bench testing and engineering analysis, not a clinical MRMC study.

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

This question is not directly applicable as the device is a physical knee implant component, not a software algorithm. The "standalone" performance here refers to the physical properties of the insert as tested in a lab, separate from human implantation. The bench tests performed are essentially the "standalone" evaluation of the device's physical and mechanical characteristics.

7. The Type of Ground Truth Used

The "ground truth" for this type of device (physical implant) is established by engineering specifications, industry standards (e.g., LAL requirements), and comparative performance with a legally marketed predicate device. The tests performed (stability, contact stress, range of motion, wear, strength, fatigue, modular disassembly) are designed to assess these physical and mechanical properties against pre-defined engineering targets and the performance of the predicate.

8. The Sample Size for the Training Set

Not applicable. This is not a machine learning or AI device that requires a "training set."

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

Not applicable. This is not a machine learning or AI device that requires a "training set."

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