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The CrossRoads Screw System is indicated for fracture repair and fixation, osteotomy, joint fusion, reconstruction and arthrodesis of bones appropriate for the size of the device.

The CrossRoads Screw System is comprised of bone screws having various features in a variety of diameters and lengths to accommodate differing patient anatomy.

This document describes the CrossRoads Screw System, a bone fixation fastener. The acceptance criteria and the study that proves the device meets those criteria are detailed below, based on the provided text.

1. Table of Acceptance Criteria and Reported Device Performance

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

The provided text describes "theoretical analysis" and "predicted performance" rather than physical testing on a 'test set' in the traditional sense of a clinical or laboratory study with a distinct sample size. The analysis appears to be computational/theoretical in nature.

• Sample Size: Not explicitly stated as a numerical sample size for a "test set" of physical devices. The analysis was performed on "worst case CrossRoads screws." This implies a selection of device configurations that are considered most challenging from an engineering perspective, rather than a random sample.
• Data Provenance: The study is described as "theoretical analysis." This suggests the data is derived from engineering calculations and modeling, rather than empirical data from human subjects or physical tests on manufactured devices that would have a country of origin.

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

Not applicable. The "ground truth" for this type of engineering performance study (torsional and pullout strength) is based on established engineering principles, material properties (ASTM F136 titanium alloy and ASTM F138 stainless steel), and calculation methods. It does not involve expert consensus on medical images or clinical outcomes.

4. Adjudication Method for the Test Set

Not applicable. There is no human interpretation or subjective assessment that would require an adjudication method. The study relies on calculated engineering values.

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

No, an MRMC comparative effectiveness study was not done. This study focuses on the mechanical properties of a medical device (screws) through theoretical analysis, not on the interpretation of medical images or clinical effectiveness where human readers would be involved.

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

This question is typically relevant for AI/ML-based diagnostic devices. In the context of a mechanical device like a screw system, the "standalone" performance refers to its intrinsic mechanical properties as determined by the theoretical analysis. The study described is precisely a standalone performance assessment of the device's predicted mechanical characteristics (torsional and pullout strengths) without human intervention in the performance itself (though humans designed the device and conducted the analysis).

7. The Type of Ground Truth Used

The "ground truth" for this study is based on:

• Established engineering principles and material science.
• Calculated values derived from theoretical models for torsional and pullout strengths.
• Performance of legally marketed predicate devices (K143039 CrossRoads Screw System, K000080 and K024060 Stryker Asnis III Screw System), which serve as a benchmark for "substantial equivalence."

8. The Sample Size for the Training Set

Not applicable. This is not an AI/ML study that uses a "training set." The study involves theoretical engineering analysis.

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

Not applicable, as there is no "training set" for this type of engineering performance study.

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