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The WMT Modular Ulnar Head Implant is indicated for the following indications:

• Replacement of the distal ulnar head for disorders of the distal radioulnar joint in rheumatoid, degenerative and post-traumatic arthritis presenting with the following findings:
  • -pain and weakness of the wrist joint not improved by nonoperative treatment;
  • -instability of the ulnar head with radiographic evidence of dislocation or erosive changes of the distal radioulnar joint;
  • -failed ulnar head resection; e.g. Darrach resection
• Primary replacement after fracture of the ulnar head or neck.
• Revision following failed ulnar head arthroplasty.

The design features of the WMT Modular Ulnar Head Implant (Figure 1) is substantially equivalent to the Avanta uHead™ modular ulnar head implant (previously submitted and cleared under AVANTA ULNAR HEAD IMPLANT -- 510(k): K010786).

The WMT Modular Ulnar Head Implant was designed as a more anatomic alternative to the previously submitted and cleared Avanta uHead™ modular ulnar head implant (previously submitted and cleared under AVANTA ULNAR HEAD IMPLANT – 510(k): K010786) that utilizes axisymmetric head and stem components. The anatomy of the distal ulna is not axisymmetric, but rather consists of a head that is offset medial-lateral and dorsal-volar from the ulnar canal. Cadaveric analysis has shown that there is no correlation between head and stem location, thus a system where the head is offset relative to the stem is required to replicate normal anatomy and thus, joint kinematics.

The WMT Modular Ulnar Head is manufactured from cobalt chrome (ASTM F799 or F1537). The triangulated head will have a highly polished exterior surface across the articulating arc and distal surface, and will have a plasma sprayed textured surface laterally for tissue adhesion. The heads will be available in sizes ranging from 16mm to 22mm in diameter, 8mm to 11mm in height, and 1.5mm to 3mm in offset. The WMT Modular Ulnar Head Implant will contain suture holes for attaching soft tissues and a locking taper mechanism for engaging the modular head onto the stem.

The WMT Modular Ulnar Stem is manufactured from titanium (ASTM F136). The stems will be available in a standard and revision option: the standard stem will be tapered 4.5° to match the anatomical canal geometry while the revision stem will have a 1º taper to match proximal canal geometry. Each stem option will be available in distal diameters ranging from 5.5mm to 8mm and in two lengths: a standard length will have a 1mm platform and 25mm stem, and the extended length will have a 20mm platform and a 50mm stem. The stems will be fluted and will have a heavy grit blast finish over entire part except for the taper.

The provided text is a 510(k) summary for the WMT MODULAR ULNAR HEAD. It describes the device and its intended use, and claims substantial equivalence to a previously cleared device (Avanta uHead™ modular ulnar head implant). However, it does not contain any information about acceptance criteria, specific performance study results (statistical metrics, sample sizes, ground truth establishment, expert qualifications, adjudication methods), or MRMC studies.

The core of this submission is a claim of "substantial equivalence" based on design features, materials, and intended use, rather than a detailed performance study against explicit acceptance criteria.

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

Here's what can be extracted:

1. Table of Acceptance Criteria and Reported Device Performance

Not explicitly stated. The document asserts "substantial equivalence" to a predicate device (Avanta uHead™ modular ulnar head implant) based on shared intended use, materials, and design features. It does not provide quantitative acceptance criteria or specific performance metrics obtained from a study comparing the WMT Modular Ulnar Head implant to these criteria.

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

Not applicable. The document does not describe a clinical or performance study with a test set of data. The "testing results" mentioned generally refer to materials data and mechanical testing to support the safety, but not a study to evaluate performance against specific criteria.

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

Not applicable. Ground truth establishment is irrelevant as no test set requiring such expert assessment is described.

4. Adjudication Method for the Test Set

Not applicable. No test set or expert adjudication process is described.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance

Not applicable. This device is a physical implant, not an AI-assisted diagnostic tool. Therefore, an MRMC study and AI-related metrics are irrelevant.

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

Not applicable. This device is a physical implant, not an algorithm.

7. The Type of Ground Truth Used

Not applicable. As above, no test set with ground truth is discussed.

8. The Sample Size for the Training Set

Not applicable. No training set is mentioned as this is not a machine learning or AI-based device.

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

Not applicable. No training set with ground truth is discussed.

Summary of what is present in the document:

The 510(k) submission for the WMT Modular Ulnar Head states its safety and effectiveness are supported by:

• Substantial equivalence information
• Materials data
• Testing results (implied mechanical/biocompatibility testing, not clinical performance against specific metrics)

The main argument for clearance is based on the device being "substantially equivalent" to the Avanta uHead™ modular ulnar head implant (K010786) in terms of intended use, materials, type of interface, and design features. The design differences (e.g., more anatomic shape, different sizing options) are presented as improvements, but without a comparative clinical performance study.

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