(189 days)
The NexFlex Total Knee System is indicated for:
- Painful, disabling joint disease resulting from rheumatoid arthritis, post-traumatic . arthritis, osteoarthritis, or degenerative arthritis
- . Failed osteotomies, unicompartmental replacement, or total knee replacement
- Post-traumatic loss of knee joint configuration and function .
- Moderate varus, valgus, or flexion deformity in which the ligamentous structures can . be returned to adequate function and stability
The NexFlex Total Knee System is intended for cemented use only.
The NexFlex Total Knee System consists of femoral components, tibial base components, tibial inserts, all-polyethylene tibial components, cancellous bone screws, a tibial screw hole cap, tibial stem extensions, and patellar components. The components of this system are designed to be used together and cannot be used as part of another system, nor can components of another system be incorporated into use with the NexFlex Total Knee System.
NexFlex femoral components are manufactured from cobalt-chromium alloy and are available in a range of sizes and in left and right orientations. They are available with or without a commercially pure titanium plasma sprayed inner surface.
Tibial base components are manufactured from titanium (Ti-6Al-4V) alloy and are available in a range of sizes. They are available with or without a commercially pure titanium plasma sprayed distal surface.
Tibial inserts are manufactured from ultra-high molecular weight polyethylene and are available in a range of sizes to match the tibial base components. The distal side of the tibial inserts has geometry to allow a mechanical lock to the tibial base components of corresponding size. The proximal side of the tibial inserts has geometry that allows articulation with the femoral components. Tibial inserts are available with two different proximal geometries, allowing for different amounts of constraint and contact area with the femoral components. A number of thicknesses of inserts are offered.
All-polyethylene tibial components are manufactured from ultra-high molecular weight polyethylene and are available in a range of sizes and thicknesses. These components have distal geometry similar to the tibial base components and proximal geometry similar to the tibial inserts.
Cancellous bone screws are manufactured from titanium (Ti-6Al-4V) alloy and are available in a range of lengths. The screws are designed to go through the tibial base component to secure it to the proximal tibia.
Tibial screw hole caps are manufactured from titanium (Ti-6Al-4V) alloy. They are designed to thread into the tibial base components to cover the screw holes when a cancellous bone screw is not used.
Tibial stem extensions are manufactured from titanium (Ti-6A1-4V) alloy and are available in a range of diameters and lengths. The stems are designed to mate with the tibial base components by means of a mechanical engagement.
Patellar components are manufactured from either ultra-high molecular weight polyethylene or a combination of ultra-high molecular weight polyethylene and titanium (Ti-6Al-4V) alloy. They are designed with posterior geometry that allows articulation with the femoral components. Patellar components with titanium backing have a commercially pure titanium plasma spraved anterior surface.
Here's an analysis of the provided text regarding the NexFlex Total Knee System, focusing on acceptance criteria and supporting studies:
Based on the provided 510(k) Summary for the NexFlex Total Knee System, the product is a medical device (a semi-constrained total knee prosthesis) submitted for premarket notification to the FDA. For such devices, acceptance criteria and studies typically focus on demonstrating substantial equivalence to legally marketed predicate devices, rather than establishing de novo performance metrics like sensitivity/specificity for a diagnostic AI. The "acceptance criteria" here implicitly refer to meeting the safety and effectiveness standards demonstrated by the predicate devices through mechanical testing and comparison of design, function, materials, and indications for use.
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Implicit) | Reported Device Performance (Summary) |
|---|---|
| Mechanical Strength & Durability (Withstanding in-vivo loading without failure) | "Mechanical testing of the NexFlex Total Knee System was performed in accordance with the recommended testing listed in the Draft Guidance... Testing indicated that the system is capable of withstanding in vivo loading without failure." |
| Material Biocompatibility | Implied by using materials (cobalt-chromium alloy, titanium alloy, ultra-high molecular weight polyethylene) found in predicate devices. |
| Design & Function Similarity | Explicitly stated: "similar to each of the listed predicate devices in one or more of the following areas: design, function..." |
| Indications for Use Similarity | Explicitly stated: "similar to each of the listed predicate devices in one or more of the following areas: ...and indications for use." |
2. Sample Size Used for the Test Set and Data Provenance
The provided 510(k) summary does not mention a clinical "test set" or data provenance in the context of human studies for performance or AI applications. The "testing" referred to is mechanical testing of the device itself.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
This information is not applicable to the provided document. The submission pertains to a knee prosthesis, not an AI/diagnostic device that would require expert-established ground truth from a test set of data.
4. Adjudication Method for the Test Set
This information is not applicable to the provided document for the same reasons as #3.
5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study was Done
No, an MRMC comparative effectiveness study was not done, and this type of study is not relevant for a knee prosthesis 510(k) submission. These are typically for diagnostic devices, often involving AI.
6. If a Standalone (i.e. algorithm only, without human-in-the-loop performance) was Done
No, a standalone algorithm performance study was not done. The NexFlex Total Knee System is a physical medical device, not an algorithm or AI.
7. The Type of Ground Truth Used
The "ground truth" in this context is established by the performance of the predicate devices and the established safety and effectiveness of the materials and design principles used in total knee prostheses. For the mechanical testing, the "ground truth" is engineering standards and the ability to withstand simulated physiological loads without failure.
8. The Sample Size for the Training Set
This information is not applicable as the device is not an AI/algorithm and therefore does not have a "training set."
9. How the Ground Truth for the Training Set was Established
This information is not applicable for the same reasons as #8.
Summary of the Study that Proves the Device Meets Acceptance Criteria:
The study that proves the NexFlex Total Knee System meets its implicit acceptance criteria (which are primarily substantial equivalence to predicate devices and mechanical integrity) is described as "Non-Clinical Performance Data":
- Study Type: Mechanical testing.
- Methodology: Performed in accordance with the "recommended testing listed in the Draft Guidance for the Preparation of Premarket Notifications (510(k)s) for Cemented, Semi-Constrained Total Knee Prostheses." This guidance likely specifies various wear, fatigue, static strength, and other biomechanical tests relevant to knee implants.
- Results/Conclusion: "Testing indicated that the system is capable of withstanding in vivo loading without failure."
- Comparison: The results of these mechanical tests, coupled with the comparison of the NexFlex system's design, function, materials, and indications for use to the Miller/Gallante Total Knee System (Zimmer, Inc.), AGC Total Knee System (Biomet, Inc.), AMK Total Knee System (DePuy, a Johnson Company), and Series 7000 Total Knee System (Stryker/Osteonics), formed the basis for the FDA's determination of substantial equivalence. This determination effectively means the device meets the regulatory acceptance criteria for market entry.
§ 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.