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The Natural-Knee II Revision Femoral Spacer Lugs are intended for cemented use with the previously cleared Natural-Knee II Revision Femoral Component and associated components (e.g., tibial, patellar, etc.) in the treatment of:

• Patient conditions of noninflammatory degenerative joint disease (NIDJD), e.g., avascular 1. necrosis, osteoarthritis, and inflammatory joint disease (IJD), e.g., rheumatoid arthritis.
• Correctable valgus-varus deformity and moderate flexion contracture. 2.
• Those patients with failed previous surgery where pain, deformity or dysfunction persists. 3.
• Revision of previously failed knee arthroplasty. 4.

The Natural-Knee II Revision Femoral Spacer Lug is in effect a bolt. The threaded portion of the lug screws into blind holes on the inner box of the Natural-Knee II Revision Femoral Component. A large hexagonal head allows the lug to be tightened into place. When used with a femoral spacer, the lug holds the spacer component firmly in place. When used without the spacer, the lug provides medial-lateral stability similar to that of conventionally cast or machined pegs usually found on the inner box of most femoral components.

This 510(k) summary describes a medical device, the Sulzer Orthopedics Inc. Natural-Knee® II Revision Femoral Spacer Lugs, which is a mechanical orthopedic implant. The provided document does not contain information about software, algorithms, or AI. Therefore, it is not possible to answer the questions related to acceptance criteria for an AI/algorithm, study design for AI performance, ground truth establishment, or multi-reader multi-case studies as these concepts are not applicable to the device described.

However, based on the provided text, the closest equivalent to an "acceptance criteria" and "study" for this mechanical device would be the analysis of its shear strength.

Here's an interpretation based on the provided text:

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

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

• Sample size: Not specified. The document states "Analysis of the lug shear strength," implying a test was conducted, but the number of lugs tested is not mentioned.
• Data provenance: Not specified. It's likely an in-house laboratory test conducted by the manufacturer, but the location or whether it involved actual patient data (unlikely for shear strength) is not mentioned. It is a prospective test in the sense that it was conducted as part of the device's development/validation.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

Not applicable. For a mechanical shear strength test, "ground truth" is typically defined by engineering specifications and physical test standards, not by expert consensus on interpretations.

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

Not applicable. This is not a diagnostic device involving human interpretation.

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 is a mechanical orthopedic implant, not an AI or imaging device.

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

Not applicable. This is a mechanical orthopedic implant, not an algorithm.

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

The "ground truth" for the shear strength test would be based on engineering standards and established physiological load requirements for implantable devices in the knee joint. The criteria for "survive physiologic loading" would be determined by biomechanical engineers based on expected forces in the human knee during various activities.

8. The sample size for the training set

Not applicable. This is a mechanical device, not an AI model requiring a training set.

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

Not applicable. This is a mechanical device.

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