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KURZ middle ear prostheses are intended for the partial or total surgical replacement of the ossicular chain of the human middle ear. The objective is the restoration of the mechanical transfer of sound from the tympanic membrane to the oval window of the cochlear with the least impairment of hearing.

Specifically, the devices are designed for the treatment of

1. Chronic middle ear inflammation (also following removal of a tumour, e.g. cholesteatoma) with functional impairment of the ossicular chain
2. Otosclerosis (stapedial fixation) / congenital stapedial fixation
3. Traumatic injury to the ossicular chain
4. Malformation of the middle ear
5. Revision surgery to correct inadequate hearing improvement, e.g. through dislocation of a prosthesis

Due to different preferences and different techniques of the surgeons various designs of stapes prosthesis are available. The objective of all stapedial prostheses is the restoration of the mechanical transfer of sound from the tympanic membrane to the oval window of the cochlear with the least impairment of hearing.

NiTiFLEX Stapes Prosthesis:
The NiTiFLEX is a stapes prosthesis for partial replacement of the ossicular chain. It consists of a Nitinol clip and the standard KURZ shaft (piston) made of pure titanium with a diameter of 0.4 and 0.6 mm (ASTM F67). The Nitinol clip is made of superelastic Nitinol. Due to the CliP Design, already available with the predicate device CliP® Piston àWengen, the NiTiFLEX can be fixed on the long process of the incus without manual crimping. With the superelastic characteristics of the loop the easier handling of the application of the CliP can be achieved.

Detroit Piston:
The Detroit Piston is a stapes prosthesis for partial replacement of the ossicular chain. It is made of pure titanium (ASTM F67). As shaft the standard KURZ piston is used with a diameter of 0.4 / 0.5 / 0.6 mm. The loop has got a width of 0.5 mm and is twisted (like the loop of the predicate device K-Piston) for easier application on the long process of the incus especially in cases were the incus diameter is very small. The attachment to the incus is done by manual crimping of the prosthesis loop.

Roberson Stapes Prosthesis:
The Roberson Stapes Prosthesis is a stapes prosthesis for partial replacement of the ossicular chain. It is made of pure titanium (ASTM F67). The long process of the incus is placed within the bucket. Two different diameters of the bucket are available - 0.9 and 1.0 mm - for different incus diameters. A piston diameter of 0.6 mm is used. Additional stability is provided by the wire that is placed over the incus. This design is comparable to the Roberson Stapes Prosthesis by Metronic (predicate device).

Skarzynski Piston:
The Skarzynski Piston is a stapes prosthesis for partial replacement of the ossicular chain. It is made of pure titanium (ASTM F67). As shaft the standard KURZ piston is used with a diameter of 0.4 and 0.6 mm. The loop has got a width of 0.25 mm and is twisted (like the loop of the predicate device K-Piston) for easier application on the long process of the incus especially in cases were the incus diameter is very small. The attachment to the incus is done by manual crimping of the prosthesis loop.

The provided document describes the 510(k) summary for several stapes prostheses manufactured by Heinz Kurz GmbH Medizintechnik. This is a premarket notification for medical devices, which typically focuses on demonstrating substantial equivalence to a predicate device rather than presenting new clinical study data to prove efficacy. Therefore, much of the requested information regarding "acceptance criteria" for performance metrics like sensitivity/specificity, or detailed clinical study designs with ground truth established by experts, will not be present in this type of submission. The "acceptance criteria" here refer more broadly to the regulatory requirements for showing safety and effectiveness through substantial equivalence and meeting specified non-clinical performance benchmarks.

Based on the provided document, here's an analysis of the acceptance criteria and the study that proves the device meets those criteria:

1. Table of Acceptance Criteria and Reported Device Performance

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

The provided document primarily details a non-clinical (bench) testing and regulatory submission process for substantial equivalence, not a clinical study with human subjects.

• Test Set Sample Size: No information on a "test set" in the context of clinical data (e.g., patient cases) is provided. The performance testing refers to bench testing, for which sample sizes for each specific test (e.g., MRI testing, biocompatibility, attachment forces) are not detailed in this summary.
• Data Provenance: The document does not refer to clinical data (e.g., country of origin, retrospective/prospective). All referenced testing appears to be laboratory-based ("Bench testing") conducted by the manufacturer, Heinz Kurz GmbH Medizintechnik, based in Germany.

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

This type of information is not applicable or available in this document. The submission focuses on substantial equivalence based on material, design, and non-clinical performance characteristics, not on clinical effectiveness studies requiring expert-adjudicated ground truth.

4. Adjudication Method for the Test Set

This type of information is not applicable or available in this document, as there is no mention of a human-adjudicated test set.

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

This information is not applicable. This document describes a medical device (stapes prostheses), not an AI-powered diagnostic or assistive tool. Therefore, no MRMC study or AI-related comparative effectiveness is mentioned.

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

This information is not applicable. This document describes a medical device, not an algorithm, and therefore human-in-the-loop performance or standalone algorithm performance is not relevant.

7. The Type of Ground Truth Used

For the non-clinical performance testing, the "ground truth" would be established by:

• Industry standards and regulatory requirements: e.g., ASTM F2119, F2052, F2182 for MRI safety; EN ISO 10993 for biocompatibility; EN ISO 11607 for shelf life and packaging; EN ISO 11137 for sterilization.
• Engineering specifications and measurements: For design parameters like dimensions, attachment forces, and material properties.

For the purpose of the 510(k) submission, the ultimate "truth" is the demonstration of substantial equivalence to predicate devices in terms of intended use, technology, and safety/effectiveness performance, rather than an independently established "ground truth" of a disease state.

8. The Sample Size for the Training Set

This information is not applicable or available. No "training set" in the context of machine learning or clinical data is mentioned in this document.

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

This information is not applicable or available, as there is no mention of a "training set" or corresponding ground truth establishment.

Summary of the Study Proving Acceptance Criteria:

The "study" proving the device meets acceptance criteria, in the context of this 510(k) submission, is a comprehensive set of non-clinical bench tests and comparisons to predicate devices.

The manufacturer, Heinz Kurz GmbH Medizintechnik, conducted the following tests to demonstrate safety and effectiveness and substantiate equivalence:

• NiTiFLEX Specific Test: Attachment Forces (details on criteria/results not in summary).
• All Products:
  • MRI Environment Testing: Conducted according to ASTM F2119, F2052, F2182, demonstrating MR Conditional status at 1.5, 3, and 7 Tesla.
  • Biocompatibility Testing: Conducted according to EN ISO 10993.
  • Shelf Life Testing: Conducted according to EN ISO 11607.
  • Sterilization Validation: Conducted according to EN ISO 11137-1, 11137-2 (Gamma Sterilization), achieving a sterility assurance level (SAL) of < 10^-6.
  • Packaging Validation: Conducted according to EN ISO 11607.

The document states that these tests, along with detailed comparisons of the new devices to legally marketed predicate devices (K002221, K021479, K112616, etc.) in terms of intended use, design, materials, and other specifications, demonstrated that the Kurz Stapes Prostheses are "as safe and effective as the predicate devices." The conclusion is that "Nonclinical and clinical testing demonstrated that the Kurz Stapes Prostheses are as safe and effective as the predicate devices. The results of non-clinical design performance validations raise no new issues of safety and effectiveness." (Note: The "clinical testing" mentioned here is likely a boilerplate reference or refers to existing clinical knowledge about predicate devices, as no new clinical study data is presented for these specific devices in the summary).

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