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The Stryker VariAx 2 Wrist Fusion System is indicated for wrist arthrodesis and fixation of fractures in patients with wrist arthritis or fractures of other small bones of the carpus. Specific indications include:

• Post-traumatic arthritis of the joints of the wrist .
• Rheumatoid wrist deformities requiring restoration ●
• Complex carpal instability ●
• Post-septic arthritis of the wrist ●
• Severe unremitting wrist pain related to motion
• Brachial plexus nerve palsies
• o Tumor resection
• Spastic deformities

VariAx 2 Wrist Fusion System is a fixation device that consists of plates with different design (standard bend, short bend, and straight) manufactured from Commercially Pure Titanium Grade 2 (ASTM F67). The plates will be available sterile and non-sterile. VariAx 2 Wrist Fusion System will be used with locking and non-locking screws (2.3mm, 2.7 and 3.5mm) previously cleared in K040022 (Stryker® Leibinger Universal Distal Radius System), K073527 (VariAx™ Elbow System), K080667 (VariAx™ Distal Radius Torx Screws), and K140769 (VariAx 2 System). VariAx 2 Wrist Fusion System will be used with new and existing instruments previously cleared in K101056 (VariAx Elbow System), K130009 (VariAx 2 Compression Plating System), and K140769 (VariAx 2 System).

This document describes a 510(k) premarket notification for the Stryker VariAx 2 Wrist Fusion System, a metallic bone fixation appliance. The FDA determined the device is substantially equivalent to legally marketed predicate devices.

Here's an analysis based on your requested information:

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

Since this is a 510(k) submission based on substantial equivalence, the "acceptance criteria" are implied by the performance of the predicate device. The goal is to demonstrate that the new device is as safe and effective as the predicate.

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

The document states: "Non-clinical laboratory testing was performed on the worst case subject plates to determine substantial equivalence."

• Sample Size: The exact sample size for the mechanical testing is not specified in this document. It refers to "worst case subject plates," implying a representative selection, but the number is not given.
• Data Provenance: The testing was "non-clinical laboratory testing." The country of origin of the data is not specified, but the sponsor is Stryker Trauma AG, located in Switzerland, and the contact person is in Germany. The testing itself would likely have occurred in a laboratory setting associated with the manufacturer or a contracted testing facility. It is prospective in nature, as it's testing performed specifically for this submission.

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)

This device is a mechanical implant, not an AI/diagnostic device. As such, "ground truth" in the context of expert consensus for diagnostic interpretation is not applicable. The "ground truth" for the non-clinical testing is established by the ASTM F382-14 standard for metallic bone plates, which defines the acceptable mechanical properties. The "experts" in this context would be the engineers and technicians performing and interpreting the mechanical tests according to the standard. Their qualifications are not specified but would be in mechanical engineering or materials science.

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

Adjudication methods like 2+1 or 3+1 are typically for clinical studies involving human interpretation or subjective endpoints. For non-clinical mechanical testing, there is no adjudication method mentioned or typically required in the same sense. The results are quantitative measurements against an established standard (ASTM F382-14). Discrepancies would be handled through repeat testing or calibration, not expert consensus.

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 MRMC study was done. This is a hardware implant device, not an AI or diagnostic software.

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

Not applicable. This section is for AI/software devices. The device is a physical bone fixation system.

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

For the non-clinical mechanical testing, the "ground truth" for evaluating the device's performance is:

• Compliance with the ASTM F382-14 'Standard specification and test method for metallic bone plates'. This standard defines the acceptable mechanical properties, such as fatigue strength.

8. The sample size for the training set

Not applicable. This device is a hardware implant and does not involve AI or machine learning algorithms that require a "training set."

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

Not applicable. See point 8.

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