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The VariAx 2 Mini Fragment System is indicated for fracture fixation, replantation, stabilization, reduction, fusions, osteotomies, mal-unions of small bones and small bone fragments including normal and osteopenic bones in adult and adolescent (12 - 21 years) patients. The system is also indicated for non-load bearing stabilization and reduction of bone fragments in long bones.

The VariAx 2 System is indicated for adult and pediatric patients, where the implant would not cross open growth plates, for the treatment of normal or osteopenic bone for the following conditions or procedures:

• · Fracture fixation, including single, segmental, and comminuted fractures
• · Revision, including nonunion and malunion
• Intra- and extra-articular fractures
• · Compression fracture
• Displaced fracture
• · Reconstruction
• · Replantation
• · Arthrodesis
• Osteotomy

The VariAx 2 Mini Fragment System is used for internal fixations and is composed of sterile and nonsterile plates. Additionally, the plates are provided in locking and non-locking options, as well as various lengths, thicknesses, and configurations.

The VariAx 2 System is used for internal fixation applications and is composed of sterile and nonsterile screws, washers, and instruments. In addition to independent use, screws of this system are also used with compatible, internal fixation systems. These devices are made of commercially pure titanium and titanium alloy with Type III anodization, and are available in a variety of sizes and diameters, as well as locking and non-locking types.

The provided document is a 510(k) premarket notification for the Stryker VariAx 2 System and VariAx 2 Mini Fragment System. This type of submission relies on demonstrating substantial equivalence to a legally marketed predicate device, rather than proving safety and effectiveness through clinical trials with specific acceptance criteria as might be seen for novel devices.

Therefore, the document does not contain the detailed information requested regarding acceptance criteria and a study proving the device meets them in the way this request envisions for a software or AI-based medical device.

However, I can extract the information provided about the non-clinical testing performed to demonstrate substantial equivalence, which serves a similar purpose in the context of a 510(k) submission.

Here's the breakdown of what is available based on the provided text:

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

The document does not specify quantitative acceptance criteria. Instead, it states that "The aforementioned testing demonstrated that the VariAx 2 Mini Fragment System and the VariAx 2 System are substantially equivalent to the predicate devices." This implies that the performance of the new devices in these tests was comparable to or better than the predicate devices, satisfying the FDA's requirement for substantial equivalence for mechanical properties.

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 does not specify the sample sizes (e.g., number of screws, plates tested) for the non-clinical mechanical tests. It also does not provide information on data provenance as these are physical device tests, not data-driven studies.

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. This was a non-clinical, mechanical testing study of physical medical devices, not a study involving expert interpretation of data.

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

Not applicable. This was a non-clinical, mechanical testing study.

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 was a non-clinical, mechanical testing study, not a human reader study involving AI.

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

Not applicable. This was a non-clinical, mechanical testing study.

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

For the mechanical tests, the "ground truth" or reference for comparison was the performance of the identified predicate devices (Smith & Nephew Variable-Angle Locking Mini-Fragment Plating System (K132886) and Synthes (USA) Modular Mini Fragment LCP System (K063049) for the Mini Fragment System, and VariAx 2 System (K180500) for the VariAx 2 System). The tests measured physical properties and compared them against known standards or the predicate's performance. For MRI safety, the ground truth would be established by industry standards or FDA guidance for MR compatibility.

8. The sample size for the training set

Not applicable. This was a non-clinical, mechanical testing study, not an AI or machine learning study requiring a training set.

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

Not applicable. This was a non-clinical, mechanical testing study.

Summary of the Study:

The study referenced in the 510(k) submission is a non-clinical mechanical testing study. Its purpose was to demonstrate substantial equivalence of the VariAx 2 Mini Fragment System and the VariAx 2 System to their respective predicate devices.

Tests Performed:

• Torsion
• Insertion Torque
• Pull-out
• Four-point bending
• MRI assessments (magnetically-induced displacement force, magnetically-induced torque, RF-induced heating, and image artifacts)

Conclusion of the Study:

The non-clinical testing "demonstrated that the VariAx 2 Mini Fragment System and the VariAx 2 System are substantially equivalent to the predicate devices." Additionally, the devices were found to be MR conditional. Clinical testing was not required for this submission.

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