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The Twister™ Superelastic Ligating Clip, Size M, and its applier is intended for the permanent occlusion or ligation of blood vessels and other tubular body structures, wherever a metal ligating clip is indicated, and within the size range of 2.0 to 3.5mm diameter.

The Twister" Superelastic Ligating Clip System comprises a dedicated applier containing a number of Twister™ Superelastic Ligating Clips held in-train in an unstretched state. The applier consists of a front nozzle, handle and main body with a trigger. The clips are applied by a two stage trigger activation process of the applier; in the first step the clip is advanced and stretched to an open position, and in the second step the clip is released into position on the vessel or structure to be ligated. Prior to activation, the applier nozzle design allows for assessment of the suitability of a particular clip size in relation to that of the blood vessel, or other body tubular structure. Surgeons should only apply an appropriately sized clip for the size of vessel or tissue structure to be ligated, such that the clip completely encompasses the vessel or tissue structure. The specific nozzle design is intended to assist the surgeon in optimal clip application, by virtue of its shape and external guide markings.

The Twister™ clip is manufactured from a Superelastic Nitinol alloy, which has a shape memory effect. During application of the Twister™ clip, the clip is opened for placing over the vessel or structure. On its release from the applier, the Twister™ clip resumes its original 'shape memory' closed position, and its arms encircle the vessel or structure - effectively ligating the vessel or structure by applying a pressure.

The Twister™ clip and its applier are single use medical devices and both the applier and any remaining unused clips should be discarded following the surgical procedure The Twister applier and clips are not intended for re-sterilization.

The provided text is a 510(k) summary for the Twister™ Superelastic Ligating Clip and Applier. It describes the device, its intended use, and claims substantial equivalence to predicate devices. However, this document does not contain any information regarding specific acceptance criteria, a study proving the device meets those criteria, or performance metrics like sensitivity, specificity, accuracy, or any sample sizes used for testing.

This 510(k) submission primarily focuses on:

• Device Description: What the device is and how it works.
• Intended Use: The clinical purpose of the device.
• Substantial Equivalence: Arguing that it is similar enough to previously approved devices that new clinical trials are not necessary. This is a common pathway for Class II devices.

Therefore, most of the requested information cannot be extracted from the provided text.

Here is a breakdown of what can be inferred or directly stated, and what is missing:

1. Table of Acceptance Criteria and Reported Device Performance

• Acceptance Criteria: Not explicitly stated in terms of quantitative performance metrics (e.g., "device must achieve X% accuracy").
• Reported Device Performance: Not reported in terms of specific sensitivity, specificity, or accuracy. The document states: "Differences between the subject device and the predicate devices were the subject of laboratory and animal studies to establish safety and effectiveness. The biocompatibility of the materials used in the subject device has also been established." However, no results or performance thresholds from these studies are provided in this summary.

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

• Sample Size for Test Set: Not mentioned.
• Data Provenance: The document refers to "laboratory and animal studies," which suggests non-human data. The submitter is from the United Kingdom.

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

• Number of Experts: Not mentioned.
• Qualifications of Experts: Not mentioned.

4. Adjudication Method for the Test Set

• Not mentioned.

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

• No MRMC or human-in-the-loop study is mentioned. The focus appears to be on the device's physical properties and performance in non-human studies.

6. If a Standalone (Algorithm Only) Performance Study Was Done

• This device is a physical medical instrument (ligating clip and applier), not an algorithm or AI. Therefore, a standalone algorithm performance study is not applicable.

7. The Type of Ground Truth Used

• Based on the mention of "laboratory and animal studies to establish safety and effectiveness," the ground truth would likely be established through direct observation of the device's mechanical performance (e.g., successful ligation, force required for closure, long-term stability in vitro or in animal tissue), and biological compatibility (e.g., lack of adverse tissue reaction). Pathology and outcomes data might have been gathered as part of these animal studies, but are not detailed.

8. The Sample Size for the Training Set

• Not applicable as this is not an AI/ML device. For physical device testing, "training set" is not a standard term. If "training" refers to initial developmental testing, those sample sizes are not provided.

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

• Not applicable for a physical device.

Summary of Missing Information:

This 510(k) summary is a high-level overview. Detailed study results, acceptance criteria, and methodology for evaluating performance (which would typically include expert involvement, ground truth establishment, and specific sample sizes) are not included in this public summary document. Such information would usually be found in the full 510(k) submission, which is not publicly available in this format, or in more detailed regulatory reports.

The FDA's statement ("We have reviewed your Section 510(k) premarket notification... and have determined the device is substantially equivalent...") indicates that the FDA did review evidence (presumably including the detailed studies mentioned) and found it sufficient for clearance under the substantial equivalence pathway, rather than requiring a Pre-Market Approval (PMA) which would necessitate extensive clinical trials to prove safety and effectiveness.

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