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U2 Total Knee System - PF+ is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral joint surface erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion deformities. This device may also be indicated in the salvage or previously failed surgical attempts or for knee in which satisfactory stability in flexion cannot be obtained at the time of surgery. Femoral Component, PF+, Tibial Baseplate, PF+, Tibial Extension Stem, Patella, Onset, E-XPE, PF+, and Patella, Asymmetric Onset, E-XPE, PF+ are indicated for both cemented and cementless use.

USTAR II Total Knee System

1. Metastatic tumor (i.e. osteosarcoma, chondrosarcoma, giant cell tumor or osteoma) where massive resection and transplantation are needed.
2. Severe knee joint damage resulting from trauma where massive resection and transplantation are needed.
3. Non-inflammatory degenerative joint disease such as avascular necrosis, osteoarthritis, or traumatic arthritis.
4. Revision of previously failed total joint arthroplasty, osteotomy, or arthrodesis.
5. Joint instability resulting from excessive bone resection.

For Femoral component, Hinged/ Tibial baseplate, Hinged/ Cemented tibial stem/ Cemented Straight stem, RHS, non coated/ Cemented Curved stem, RHS, non coated/ Cemented Straight stem, RHS/ Cemented Curved stem, RHS/ Tibial Augment: These devices are single use implant and intended for cemented use only.

For Distal Femoral Component, RHS/ Proximal Tibial Component, RHS/ Tibial stem/ Segment Part, RHS/ Segment Part, RHS, Bridge: These devices are single use implant and intended for cementless use only.

The subject PF+ Patella is a line extension of the U2 Total Knee System, and is compatible to the USTAR II System. The subject device, U2 Total Knee System–PF+ Patella; USTAR II System - PF+ Patella, is a Metal-Backed Patella, indicated for both cemented or cementless application. There are two variations available: (1) Patella, Onset, E-XPE, PF+, and (2) Patella, Asymmetric Onset, E-XPE, PF+. Patella, Onset, E-XPE, PF+ is a symmetric, dome-type metal-backed patella, and Patella, Asymmetric Onset, E-XPE, PF+ is an asymmetric, anatomic-type patella. Each type is available in five sizes. The body of PF+ patella is manufactured from Vitamin E blended highly cross-linked UHMWPE (ASTM F2695, ASTM F648/ISO5834-1), while the part of the metal back and the three pegs are produced by additive manufacturing according to the FDA guidance "Technical Considerations for Additive Manufactured Medical Devices - Guidance for Industry and Food and Drug Administration Staff", "Guidance Document for Testing Orthopedic Implants with Modified Metallic Surfaces Apposing Bone or Bone Cement", and "Guidance for Industry on the Testing of Metallic Plasma Sprayed Coatings on Orthopedic Implants to Support Reconsideration of Post market Surveillance Requirements." The metal back is made of Ti-6Al-4V alloy (ASTM 2924) and has a porous Ti structure on the bone side, peg side, and poly side. All types of PF+ Patella are compatibility with "United" U2 Total Knee System-Femoral components (K051640, K120507, K140073, K140075, K150829, and K150832), Femoral component, PSA (K082424), Femoral components, PF+ (K221705), and USTAR II System-Femoral components (K190100).

The provided text is a 510(k) Clearance Letter from the FDA for a total knee system. It details the device's name, regulation, a summary of its description, intended use, and a comparison to predicate devices, along with a list of non-clinical tests conducted.

However, the document specifically states "No clinical data is necessary." This means that the clearance was not based on a clinical study demonstrating the device's performance against detailed acceptance criteria in human patients with the format typically requested in your prompt (e.g., sensitivity, specificity, human-in-the-loop performance, ground truth establishment by experts, etc.).

Instead, the clearance is based on the substantial equivalence of the new device to existing legally marketed predicate devices, primarily through non-clinical testing and technological comparison.

Therefore, I cannot fulfill your request for a table of acceptance criteria and reported device performance from a clinical study, as no such study was presented or required for this 510(k) clearance.

The "acceptance criteria" for this device, as implied by the FDA clearance, revolve around demonstrating that its technological characteristics and non-clinical performance are substantially equivalent to already cleared devices.

Here's what I can extract from the document regarding the non-clinical tests that functionally served as part of the "proof" that the device meets some form of performance criteria:

Summary of Non-Clinical Tests (Implicit Acceptance Criteria & Performance):

Since no clinical study was conducted or referenced in this 510(k) clearance documentation, the following points of your request cannot be addressed from the provided text:

• Sample size used for the test set and data provenance: Not applicable, as no clinical test set was used. The non-clinical tests were performed on device prototypes or samples.
• Number of experts used to establish the ground truth... / qualifications of those experts: Not applicable. Ground truth for clinical performance was not established.
• Adjudication method for the test set: Not applicable.
• If a multi-reader multi-case (MRMC) comparative effectiveness study was done...: Not applicable.
• If a standalone (i.e., algorithm only without human-in-the-loop performance) was done: Not applicable, as this is a physical medical device, not an AI algorithm.
• The type of ground truth used: For the non-clinical tests, the "ground truth" is defined by established engineering and material science standards and methodologies (e.g., ASTM standards for material properties, mechanical testing protocols).
• The sample size for the training set: Not applicable. This is a physical device, not an AI model requiring a training set.
• How the ground truth for the training set was established: Not applicable.

In essence, this 510(k) clearance is a regulatory determination of substantial equivalence based on non-clinical performance data and technological comparisons to predicate devices, not on a clinical trial demonstrating performance against specific diagnostic or treatment outcome acceptance criteria in humans.

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U2 Total Knee System - PF+ is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, primary and secondary traumatic arthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral joint surface erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion deformities. This device may also be indicated in the salvage or previously failed surgical attempts or for knee in which satisfactory stability in flexion cannot be obtained at the time of surgery. Femoral Component, PF+, Tibial Baseplate, PF+ and Tibial Extension Stem are indicated for both cemented and cementless use.

There are three components included in U2 Total Knee System- PF+ for this 510k, (1)Femoral Component, PF+, (2)Tibial Baseplate, PF+, and (3)Tibial Extension Stem. Both Femoral Component, PF+ and Tibial Baseplate, PF+ can collocate with U2 Total Knee System tibial insert and patellar component (K021657, K051640, K082469, K103733, K131864, K132752, K150829, K152430, K161705, and K210961). This system includes Cruciate Retained (CR) type and Posterior Stabilized (PS) type.

• Femoral Component, PF+
There are two types of Femoral Component, PF+ : Cruciate Retaining type and Posterior Stabilized type. Femoral Component, PF+ is manufactured from cast Co-Cr-Mo alloy conforming to ASTM F75. The inner surface is coated with Co-Cr-Mo beads and Co-Cr-Mo powder (ASTM F75) to provide a porous surface to achieve biological fixation.

• Tibial Baseplate, PF+
Tibial Baseplate, PF+ is manufactured from titanium alloy (ASTM F620) which is forged by titanium alloy bars (ASTM F136). The backside of the subject device is coated with Titanium powder (ASTM F1580).

• Tibial Extension Stem
Tibial Extension Stem is collocated with tibial baseplate. The subject device is made of titanium alloy conforming to ASTM F136.

The provided document (K221705) is a 510(k) summary for a medical device called the "U2 Total Knee System-PF+". This document is a premarket notification to the FDA to demonstrate that the device is substantially equivalent to legally marketed predicate devices.

It is crucial to understand that this document describes a mechanical orthopedic implant (knee replacement components), not an AI-powered or software-based medical device. Therefore, the concepts of acceptance criteria for AI performance, training and test sets for AI models, expert ground truth for imaging, MRMC studies, or standalone algorithm performance are not applicable to this submission.

The document discusses acceptance criteria and proof of meeting them, but these relate to the mechanical and material properties, biocompatibility, and sterilization of the knee implant components, not to the performance of an AI algorithm.

Therefore, I cannot provide the requested information for an AI-powered device based on this document.

However, I can extract information relevant to the device's performance, which is related to its mechanical and material integrity:

Information from the document relevant to the device's "performance" (mechanical/material):

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

The document broadly states that "the test results indicated that this device is safe and effective" and that "Verification activities on Subject devices demonstrated equivalent safety and effectiveness as compared to the predicate devices."

Specific acceptance criteria (e.g., "fatigue strength must exceed X N at Y cycles") and the exact reported values are not explicitly provided in a table format within this 510(k) summary. The summary typically refers to the fact that these tests were conducted and met the necessary standards for substantial equivalence.

However, the types of performance tests conducted are listed:

2. Sample sized used for the test set and the data provenance:

• Sample Size: Not explicitly stated for each mechanical test. For mechanical testing of components, samples typically refer to a number of physical units or prototypes tested, not patient data.
• Data Provenance: The tests are performed by the manufacturer, United Orthopedic Corporation (located in Hsinchu City, Taiwan). The testing is primarily laboratory-based mechanical and material characterization, not clinical data. Therefore, concepts like "country of origin of the data" or "retrospective/prospective" in the clinical sense are not applicable.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience):

This question is not applicable. This device is a mechanical implant, not an AI system interpreting medical images. "Ground truth" in this context would be defined by engineering specifications, material standards (e.g., ASTM F75, F136, F620, F1580), and validated test methodologies (e.g., fatigue testing standards). The "experts" involved would be materials scientists, mechanical engineers, and quality assurance professionals, whose qualifications are implicit in the adherence to recognized standards.

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

This question is not applicable. Mechanical tests have specific physical or chemical endpoints determined by validated methods and equipment, not human subjective interpretation requiring adjudication.

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 question is not applicable. MRMC studies are for assessing diagnostic accuracy of imaging or AI systems with human readers. This device is a mechanical implant.

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

This question is not applicable. This device is a mechanical implant.

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

The "ground truth" for this device's performance is established by:

• Adherence to international and national standards for materials (e.g., ASTM F75, F136, F620, F1580).
• Validated mechanical testing methodologies (e.g., fatigue testing, surface finish measurements).
• Biocompatibility standards (e.g., USP for endotoxin).
• Comparison to the established performance characteristics of predicate devices.

8. The sample size for the training set:

This question is not applicable. There is no AI model or "training set" for this mechanical device.

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

This question is not applicable.

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The U2 Total Knee system is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthitis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion deformities. This device may also be indicated in the salvage of previously failed surgical attempts if the knee cannot be satisfactorily balanced and stabilized at the time of surgery.

For cemented femoral components, patellar components, tibial baseplate components and tibial inserts components: This device is a single use implant and intended for cemented use only.

For porous coated femoral component: This device is a single use implant and intended for cementless use only.

The U2 Total Knee System include femoral components, patellar components, tibial baseplate components and tibial inserts components which are designed to be used together to achieve total replacement of the knee joint. This system includes Cruciate Retained (CR) type, Posterior Stabilized (PS) type and Ultracongruent (UC) type. The subject device, U2 Total Knee System, XPE Tibial Insert, Posterior Stabilized PLUS (PS PLUS), belongs to U2 Total Knee System PS type.

U2 Total Knee System, XPE Tibial Insert, PS PLUS (Subject device) is a constrained design insert mechanically locked with metallic tibial baseplate. It is manufactured from Gamma irradiated UHMWPE which conform to ASTM F2565-13, while the UHMWPE raw material is in accordance with ASTM F648-14 and ISO 5834-1:2005.

The Subject device is used with the Posterior Stabilized (PS) type Femoral Component. In comparison to the marketed predicate devices, the Subject device has slightly modified width and height of the post, the height of the anterior lip. The Subject device provides constraint in varus/valgus and internal/external rotation to enhance joint stability and resist paradoxical anterior femoral slide.

Except for the differences of the post and anterior lip, the size distribution the Subject device is identical to the previously cleared Tibial Inserts of U2 Total Knee System predicates. The Subject device is available in eight proportional sizes (#0~ #7) and ten thicknesses (thicknesses of poly insert + tibial baseplate: 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm and 18mm). The minimum thickness of poly insert of Subject device is 6 mm on the bearing surface, identical to the primary predicate.

Surgical procedures with the use of the Subject device shall be performed with the support of orthopedic instrumentation, to facilitate their proper insertion and removal from the patient. The surgical instruments have been previously cleared as part of the predicate devices.

This document describes the FDA's decision regarding the substantial equivalence of the "U2 Total Knee System, XPE Tibial Insert, PS PLUS" to a predicate device. It does not contain information about the acceptance criteria or study results in the context of an AI/ML medical device.

Therefore, I cannot provide the requested information about acceptance criteria, reported device performance, sample sizes, ground truth, expert qualifications, adjudication methods, or MRMC studies, as these details are not present in the provided text.

The document is purely a regulatory clearance notice for a knee implant, focusing on its manufacturing, materials, and intended use as compared to existing, legally marketed predicate devices.

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For E-XPE Insert (CR, PS and UC type) and Patella:
The device is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion deformities. This device may also be indicated in the salvage of previously failed surgical attempts if the knee can be satisfactorily balanced and stabilized at the time of surgery. This device is a single use implant and intended for cemented use only.

For E-XPE Insert (PSA type)
This device is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion contraction. This device is intended for use in patients who require augmentation and/or stem extensions due to inadequate bone stock and/or require constrained stabilization for tibiofemoral joint due to soft tissue imbalance. This device is a single use implant and intended for cemented use only.

The subjected device includes E-XPE Tibial insert (CR, PS, UC and PSA type) and E-XPE Patella. It is an extension to the previously cleared "UNITED" U2 Total Knee System (K082424, K103733, K131864, K132752 and K150829). The design rationale and indication for use are identical to the previously cleared "UNITED" U2 Total Knee System.

The provided document is a 510(k) summary for the U2 Total Knee System E-XPE Products. It focuses on demonstrating substantial equivalence to pre-existing predicate devices for a medical device, specifically a knee implant. As such, it details pre-clinical performance data (mechanical tests) and explicitly states "None provided" for clinical performance data.

Therefore, it does not contain the information required to answer the prompt, which is about acceptance criteria and study results for an AI/algorithm-based medical device. The prompt is looking for details about an AI's performance, such as:

• Accuracy/performance metrics (e.g., sensitivity, specificity, AUC)
• Sample sizes for test and training sets related to image or data analysis
• Ground truth establishment by expert readers or pathologists
• Human-in-the-loop studies (MRMC studies)
• Adjudication methods for AI performance validation

None of this type of information is present in the provided text, as it describes a physical implant and its material/mechanical testing.

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This device is indicated in knee arthroplasty in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectorny, moderate valgus, varus, or flexion contraction. This device is intended for use in patients who require augmentations due to inadequate bone stock and/or require increased stabilization for tibiofemoral joint due to soft tissue imbalance. The femoral and tibial augments are to be attached to their respective components with a fixation screw or screws. Note: In the US, this device is for cemented use only.

U2 Total Knee System - PSA Tibial Insert is an extended design of U2 Total Knee System - PSA Type (K082424) including XPE Tibal Insert, PSA and XPE Tibial Insert, PSA, LC. This System is a patellofemorotibial polymer / metal / polymer, semi-constrained, cemented knee prosthesis, which is intended for use in patients who require augmentation and/or stem extensions due to inadequate bone stock. U2 Total Knee System - PSA Tibial Inserts are available in a range of thicknesses and in two design configurations: PSA and PSA-LC type. For the PSA tibial insert, it is intended for use in patients who require constrained stabilization for tibiofemoral joint due to soft tissue imbalance. PSA-LC (low constrained) tibial insert provide less constrained stabilization than PSA tibial insert.

The provided FDA 510(k) summary (K161360) describes the U2 Total Knee System - PSA Tibial Insert. However, it does not provide information about acceptance criteria and a study proving device performance in the context of an AI/ML powered device. This document is for a traditional medical device (knee prosthesis) and its assessment is based on mechanical testing and comparison to predicate devices, not on AI/ML parameters.

Therefore, most of the requested information regarding acceptance criteria, study details, sample sizes, expert involvement, and ground truth for an AI/ML powered device study is not applicable or not available in the provided text.

Here's a breakdown of what can be extracted and what cannot:

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

• Not applicable/Not available in the context of AI/ML performance. The document focuses on mechanical and material properties of a physical medical device. It states that "Range of Motion and Spine Fatigue Test were conducted to evaluate the safety and effectiveness of the subjected device." However, specific acceptance criteria and detailed quantitative results for these tests are not provided in this summary. It mentions that the design has the same curvature as a previously cleared device, implying that its performance in terms of constraint, contact area, and pressure should be identical.

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

• Not applicable. This information pertains to studies for AI/ML performance, not mechanical testing of a physical implant. The "test set" in this context would refer to the physical specimens used for mechanical testing, but their number and provenance are not detailed in this summary.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

• Not applicable. This is relevant for AI/ML studies. Ground truth for a physical device's mechanical testing is established by engineering standards and measurements, not expert human interpretation.

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

• Not applicable. This is relevant for AI/ML studies involving human reviewers.

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 type of study is for evaluating AI-assisted diagnostic or interpretation tools. This document describes a knee implant.

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

• Not applicable. This is for AI/ML algorithms.

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

• Not applicable in the AI/ML sense. For a physical device, "ground truth" for mechanical performance would be established through highly controlled, standardized laboratory measurements (e.g., ISO standards for knee implants). The summary states "Range of Motion and Spine Fatigue Test were conducted," implying such laboratory methods.

8. The sample size for the training set

• Not applicable. This is for AI/ML algorithms.

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

• Not applicable. This is for AI/ML algorithms.

In summary: The provided document is a 510(k) clearance letter and summary for a physical medical device (knee implant). It assesses the device's substantial equivalence to predicate devices based on design, materials, and mechanical performance tests, not on the performance of an AI/ML algorithm. Therefore, requests for AI/ML specific study parameters cannot be fulfilled from this text.

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The U2 Total Knee system is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion deformities. This device may also be indicated in the salvage of previously failed surgical attempts if the knee can be satisfactorily balanced and stabilized at the time of surgery. This device is a single use implant and intended for cemented use only.

This subjected device includes femoral component, tibial insert, XPE tibial insert and ultracongruent insert. It is a size extension to the cleared "UNITED" U2 Total Knee System (K051640, K120507, K131864, K103733, K132752, and K140073). The indications, materials, design of this subject device are identical to the cleared "UNITED" U2 Total Knee System except for its dimension.

The provided text is a 510(k) summary for the U2 Total Knee System-Additional Sizes. This document outlines the regulatory filing for a medical device and typically focuses on demonstrating substantial equivalence to a predicate device, rather than presenting a detailed study proving the device meets specific performance acceptance criteria in terms of AI/software performance.

Therefore, many of the requested categories related to AI/software performance, such as sample size for test sets, expert ground truth, adjudication methods, MRMC studies, standalone performance, and training set details, are not applicable to this type of regulatory submission for a physical knee implant.

However, I can extract information related to the device's non-clinical performance and its comparison to a predicate device, as that is the focus of this document.

Here's the breakdown of the information that can be extracted, and where applicable, a note on why certain information is not present:

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

The document does not explicitly state quantitative "acceptance criteria" for the non-clinical tests in the usual sense of a specific pass/fail threshold with reported numerical performance values against those thresholds. Instead, it states that the tests "demonstrated that this device is safe and effective." The demonstration of safety and effectiveness relies on the device having the "same basic design, intended use, materials and the same manufacturing method" as predicate devices, with the only difference being "dimension." The non-clinical tests listed below were performed to confirm performance characteristics.

Note: The document confirms these tests were conducted "in accordance with the Agency's, 'Class II Special Controls Guidance Document: Knee Joint Patellofemorotibial and Femorotibial Metal/Polymer Porous-Coated Uncemented Prostheses; Guidance for Industry and FDA'." This implies that the tests were designed and evaluated against established industry and regulatory standards, which serve as the implicit "acceptance criteria." However, the exact numerical criteria and specific results are not detailed in this summary.

2. Sample sizes used for the test set and the data provenance: Not applicable. This document describes physical device testing, not AI/software performance evaluation with a "test set" in the computational sense. The "tests" refer to laboratory-based mechanical and materials evaluations.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts: Not applicable. No "ground truth" establishment by experts in the context of image analysis or diagnostic AI is mentioned. Evaluations are based on engineering principles and test results.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set: Not applicable.

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 physical prosthetic device, not an AI software.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done: Not applicable.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc): Not applicable in the context of conventional AI/software ground truth. The "truth" for this device lies in its compliance with engineering standards, material properties, and mechanical performance under simulated physiological conditions, benchmarked against predicate devices.

8. The sample size for the training set: Not applicable. This is not an AI/machine learning device.

9. How the ground truth for the training set was established: Not applicable.

Summary of the Study that Proves the Device Meets Acceptance Criteria (as described in the document):

The "study" refers to a series of non-clinical performance tests conducted on the U2 Total Knee System-Additional Sizes. The summary states these tests were performed "in accordance with the Agency's, 'Class II Special Controls Guidance Document: Knee Joint Patellofemorotibial and Femorotibial Metal/Polymer Porous-Coated Uncemented Prostheses; Guidance for Industry and FDA'".

The key premise for demonstrating safety and effectiveness and meeting acceptance criteria, as per this 510(k) summary, is substantial equivalence to several predicate devices (e.g., "UNITED" U2 Total Knee System K051640). The document explicitly states:

• "U2 Total Knee System, Additional Sizes has the same basic design, intended use, materials and the same manufacturing method as device of the 'United' U2 Total Knee System..."
• "The only difference between the cleared and subjected device is dimension."

The non-clinical tests listed above (Range of Motion, Contact Area and Pressure, Constraint, Fatigue Compression, Locking Strength, Fatigue Performance of Insert Spine, Material Properties) were performed to confirm that, despite the dimensional differences, the additional sizes maintain the same performance characteristics as the predicate devices, thereby ensuring safety and effectiveness. The conclusion provided is that "the test results demonstrated that this device is safe and effective."

Clinical Performance Data:
The document explicitly states: "None provided as a basis for substantial equivalence." This reinforces that the substantial equivalence determination for this submission relies entirely on non-clinical data and comparison to predicate devices, rather than new clinical trials for the specific additional sizes.

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This device is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion contraction. This device is intended for use in patients who require augmentation and/or stem extensions due to inadequate bone stock and/or require constrained stabilization for tibiofemoral joint due to soft tissue imbalance.

"UNITED" U2 Total Knee System – PSA Type, Offset Stem Adapter is a modification of cleared Offset Stem Adapter (K082424). This device is manufactured from Ti-6AI-4V alloy (ASTM F136) and identical to the previously cleared offset stem adapter. The Offset Stem Adapter is intended for use in patients with inadequate bone stock. It allows the stem extension to be positioned away from the center of femoral or tibial component, and to center the stem extension within the bone medullar canal. There are three available offset sizes for the subjected device including 2, 4 and 6mm. It is able to be assembled with the femoral component, tibial baseplate and stem component utilizing Morse taper locking mechanism, and the Morse taper design is identical to our cleared Offset Stem Adapter (K082424). The modification does not affect the intended use of the device or alter the fundamental scientific technology of the device.

The provided text describes a 510(k) premarket notification for a medical device, specifically the "U2 Total Knee System - PSA Type, Offset Stem Adapter." The documentation focuses on demonstrating substantial equivalence to predicate devices and includes a section on performance data.

Here's an analysis of the acceptance criteria and the study as described in the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample size used for the test set and the data provenance

The document does not specify the sample size used for the fatigue strength test. It also does not explicitly state the data provenance (e.g., country of origin, retrospective or prospective) for this test.

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

Not applicable. This device is a mechanical implant, and its performance is evaluated through engineering tests (fatigue strength), not clinical studies requiring expert ground truth for interpretation of medical data.

4. Adjudication method for the test set

Not applicable, as the evaluation is based on a fatigue strength test rather than subjective interpretation requiring adjudication among experts.

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 document pertains to a mechanical knee implant, not an AI-powered diagnostic device.

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

Not applicable. This document pertains to a mechanical knee implant, not an algorithm.

7. The type of ground truth used

For the fatigue strength test, the "ground truth" would be the engineering standards and specifications against which the device's performance is measured. The document implies that the device met these standards, leading to the conclusion that it is "safe and effective."

8. The sample size for the training set

Not applicable. This document pertains to a mechanical knee implant, not a machine learning model that requires a training set.

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

Not applicable. As above, this is a mechanical device, not an AI system with a training set.

Summary of the Study:

The primary study mentioned to prove the device meets acceptance criteria is a fatigue strength test. This test was conducted to evaluate the structural integrity and durability of the Offset Stem Adapter. The report concludes that "the test result demonstrated that this device is safe and effective."

The basis for substantial equivalence is primarily focused on the device's similarity in intended use, raw material, design rationale, and sterilization method to previously cleared predicate devices (K082424, K093293, and K102437). This suggests that the fatigue strength test was likely performed to confirm that the modifications (specifically, the different offset sizes) did not negatively impact the mechanical performance compared to the predicate device.

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This device is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion contraction. This device is intended for use in patients who require augmentation and/or stem extensions due to inadequate bone stock and/or require constrained stabilization for tibiofemoral joint due to soft tissue imbalance.

"UNITED" U2 Total Knee System - Posterior Stabilized Augmentable (PSA) type is an extended design of "UNITED" U2 Total Knee system. It is a Patellofemorotibia, polymer/metal/polymer, semi-constrained, cemented knee prosthesis, which has a cobalt-chromium-molybenum (Co-Cr-Mo) alloy femoral component and a tibial component composed of a polyethylene insert machined from compressed molded UHMWPE and a Ti-6Al-4V metallic tibial baseplate. This system is intended for use in patients who require augmentation and/or stem extensions due to inadequate bone stock. There are a variety of components including femoral augment set, tibial augment, stem extension and offset stem adapter that provides more choices for surgeon to treat their patients. In addition, this system also provides more constraint of tibiofemoral joint when patients require more constrained stabilization due to inadequate mediolateral. anterioposterior or varus-valgus soft tissue imbalance. The components of U2 Total Knee system-PSA Type are listed as below.

The provided text describes a 510(k) summary for the U2 Total Knee System - PSA Type, a medical device. This type of submission focuses on demonstrating "substantial equivalence" to a legally marketed predicate device, rather than proving efficacy through clinical trials with defined acceptance criteria for device performance as would be seen in novel devices.

Therefore, the document does not contain the following information typically associated with complex AI/ML device studies:

• Acceptance Criteria and Reported Device Performance Table: The submission focuses on substantial equivalence to existing devices through a series of bench tests. It doesn't report performance against specific, quantifiable acceptance criteria in terms of accuracy, sensitivity, specificity, etc., that would be expected for a diagnostic or predictive AI/ML device.
• Sample sized used for the test set and the data provenance: Not applicable as it's not a clinical study on patient data.
• Number of experts used to establish the ground truth for the test set and the qualifications of those experts: Not applicable.
• Adjudication method: Not applicable.
• Multi reader multi case (MRMC) comparative effectiveness study: Not applicable.
• Standalone (i.e. algorithm only without human-in-the-loop performance) study: Not applicable.
• Type of ground truth used: Not applicable.
• Sample size for the training set: Not applicable.
• How the ground truth for the training set was established: Not applicable.

What the document does provide regarding "performance" and "acceptance criteria" through the lens of substantial equivalence:

The "acceptance criteria" here are implicitly tied to demonstrating that the new device performs "as well or better than the predicate devices in all areas tested" (Page 1) and meets ASTM standards for materials. The "study" is a series of bench tests designed to show this equivalence.

Here's the relevant information that can be extracted:

1. Table of Acceptance Criteria and Reported Device Performance:

2. Sample size used for the test set and the data provenance:

• This was a bench study, not a clinical study involving patient data. Therefore, the concept of "sample size for the test set" in the context of patient data provenance (country of origin, retrospective/prospective) is not applicable. The sample sizes would refer to the number of device components tested in each bench test, but this detail is not provided in the summary.

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

• Not applicable as this is a bench study on a medical device, not an AI/ML diagnostic interpretation where expert ground truth is established.

4. Adjudication method:

• Not applicable.

5. Multi reader multi case (MRMC) comparative effectiveness study:

• No, this was not done. This type of study is typical for diagnostic AI devices comparing human readers with and without AI assistance, which is not the nature of this device or its submission.

6. Standalone (i.e. algorithm only without human-in-the-loop performance) study:

• Not applicable, as this is a mechanical knee implant, not an algorithm.

7. The type of ground truth used:

• For the bench tests, the "ground truth" would be the established engineering specifications, material standards (ASTM), and the performance characteristics of the predicate devices.

8. The sample size for the training set:

• Not applicable as this is not an AI/ML device requiring a training set.

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

• Not applicable.

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This device is indicated in knee arthroplasty for reduction or relief of pain and/or improved knee function in skeletally mature patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion deformities. This device may also be indicated in the salvage of previously failed surgical attempts if the knee can be satisfactorily balanced and stabilized at the time of surgery. This device system is designed for cemented use only.

U2 Total Knee system is the fixed bearing type with cruciate retaining and posterior stabilized design. It is a Patellofemorotibia, polymer/metal/polymer, semi-constrained, cemented knee prosthesis, which has a cobalt-chromium-molybdenum (Co-Cr-Mo) alloy femoral component and Ti alloy tibial component composed of a insert, machined from compressed molded UHMWPE flat, mechanical locked with metallic tibial baseplate. The tibial baseplate component is made of Ti-6A1-4V alloy which has groove for cement fixation. The cruciate retaining type of femoral component has w/ and w/o beaded porous coating design, and the posterior stabilized type has only w/o. The porous coating with two layers of beads has an about 55% of porosity, a 440 um of average pore size, and its thickness is 1.0 +0/+0.3 mm. The patella is machined from extruded UHMWPE bar. This device have 3 pegs and cement groove designed for cemented use only.

The U2 Total Knee System is a semi-constrained knee prosthesis designed for cemented use in knee arthroplasty. The device was deemed substantially equivalent to the predicate device, the United UKNEE® Total Knee System (K021657), based on a series of comparative tests. The study was conducted by United Orthopedic Corporation in Taiwan and focused on engineering and performance characteristics relevant to total knee systems.

Here's an analysis of the acceptance criteria and study details based on the provided information:

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample size used for the test set and the data provenance

• Sample Size: Not explicitly stated for each test. The document mentions "test data" and implies a sufficient number of samples were tested to draw the stated conclusions for each performance metric (e.g., several samples for cyclic testing, contact area comparison). Given that this is a 510(k) submission for substantial equivalence based on in vitro testing, large clinical sample sizes are not typically required at this stage.
• Data Provenance: The device and testing were conducted by United Orthopedic Corporation in Taiwan. The data is retrospective in the sense that it's a submission of pre-market testing results to demonstrate substantial equivalence, rather than a prospective clinical trial with human subjects.

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

• This type of submission (510(k) for a medical device like a knee implant based on engineering and comparative testing) does not typically involve human "ground truth" established by medical experts in the same way an AI diagnostic algorithm might. The "ground truth" here is based on objective engineering measurements, ASTM standards, and comparison to a legally marketed predicate device. Therefore, the concept of "experts establishing ground truth" in the traditional sense for diagnostic accuracy doesn't apply. The engineers and scientists conducting the tests and interpreting the results, as well as the FDA reviewers, act as the "experts" in evaluating the data against established standards and predicate performance.

4. Adjudication method for the test set

• Not applicable as this is an engineering and materials testing submission, not a study involving human interpretation or clinical adjudication. The data is generated from physical and mechanical tests.

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 not a study involving human readers or AI assistance. It is a pre-market submission for a physical medical device (knee implant) based on engineering performance data.

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

• Not applicable. This is not an AI algorithm. It is a physical medical device.

7. The type of ground truth used

• The "ground truth" for this submission is primarily based on:
  • Engineering specifications and measurements: Directly measured physical and mechanical properties (e.g., range of motion, force, stress, dimensions).
  • ASTM standards: Adherence to established industry standards for material properties and test methods.
  • Performance of the predicate device: The UKNEE® Total Knee System serves as the direct comparative benchmark, establishing what "acceptable" performance looks like for similar devices already on the market.

8. The sample size for the training set

• Not applicable. This is not an AI/machine learning study, so there is no "training set." The device design and materials are based on established engineering principles and prior knowledge of knee arthroplasty.

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

• Not applicable, as there is no training set for this type of device submission.

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