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.

Device Description

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.

AI/ML Overview

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:

Test Conducted	Performance Indication (Implicit)
Femoral component fatigue test	Device meets fatigue life requirements for load-bearing in the knee
Tibial baseplate fatigue test	Device meets fatigue life requirements for load-bearing in the knee
Articulating surface finish of femoral component	Surface smoothness is adequate for proper articulation and wear resistance
Finish of non-articulating surface of tibial baseplate	Surface quality is appropriate for non-articulating areas (e.g., tissue contact, fixation)
Microstructure of the modified surface	Material structure is as intended, contributing to mechanical properties and biological fixation
Mechanical properties of the modified surface	Material strength, stiffness, etc., are consistent with design and predicate devices
Bacteria endotoxin testing	Endotoxin levels are below specified limits (met USP <161>) ensuring biocompatibility and safety for implantation

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 <161> 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.

Summary

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February 28, 2023

Image /page/0/Picture/1 description: The image shows the logo of the U.S. Food and Drug Administration (FDA). On the left is the Department of Health & Human Services logo. To the right of that is the FDA logo, which is a blue square with the letters "FDA" in white. To the right of the blue square is the text "U.S. FOOD & DRUG ADMINISTRATION" in blue.

United Orthopedic Corporation Cheryl Wagoner Official Correspondent 5215 Crosswinds Drive Wilmington, North Carolina 28409

Re: K221705

Trade/Device Name: U2 Total Knee System-PF+ Regulation Number: 21 CFR 888.3565 Regulation Name: Knee Joint Patellofemorotibial Metal/Polymer Porous-Coated Uncemented Prosthesis Regulatory Class: Class II Product Code: MBH. JWH Dated: January 30, 2023 Received: January 31, 2023

Dear Cheryl Wagoner:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database located at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal

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statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely,

Ting Song -S

Ting Song, Ph.D. Assistant Director DHT6A: Division of Joint Arthroplasty Devices OHT6: Office of Orthopedic Devices Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration

Indications for Use

510(k) Number (if known)

K221705

Device Name

U2 Total Knee System- PF+

l ype of Ose (Select one of Dolf), as applicable) X Prescription Use (Part 21 CFR 801 Subpart D)Over-The-Counter Use (21 CFR 801 Subpart C)
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U2 Total Knee System, PF+

Traditional 510 (k)

510(K) SUMMARY Traditional 510(k)

[as required by 21 CFR 807.92(c)]

Submitter information

Company Name:	United Orthopedic Corporation
Address	No 57, Park Ave 2, Science Park, Hsinchu City 30075, Taiwan
Telephone	+886-3-5773351 ext. 2220
Fax	+886-3-577156

Contact Person	Lois Ho, Regulatory Affairs Manager
Email address	lois.ho@unitedorthopedic.com
Date of submission	June 10, 2022

Trade Name, Common Name, Classification

Device Common Name:	Femoral component, Tibial baseplate, Tibial stem
Trade name:	U2 Total Knee System- PF+
Submitter Establishment Number:	9681642
Classification Regulation Number:	21CFR 888.3565
Classification Panel:	Orthopedic
Product Code:	MBH, JWH
Device Class:	Class II
Classification name:	Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis

Predicate devices

Primary Predicate
Product name	Manufacturer	510(k) Number
U2 Femoral Component, CR, PorousCoated	United Orthopedic Corporation	K140075, K150832
Predicate or Reference Device
U2 Total Knee System	United Orthopedic Corporation	K051640, K120507,K150829
Truliant® Porous Femoral Components	Exactech	K181794
Triathlon® Tritanium Tibial Baseplates	Stryker	K123486
Klassic® Tibial Baseplate, Porous	Total Joint Orthopedics	K162256
Klassic™ Knee Tibial Stem Extension	Total Joint Orthopedics	K140942
USTAR II Knee System	United Orthopedic Corporation	K190100
U2 Hip stem, Ti porous coated, matrix	United Orthopedic Corporation	K151316

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Device description	There are three components included in U2 Total Knee System- PF+ for this510k, (1)Femoral Component, PF+, (2)Tibial Baseplate, PF+, and (3)TibialExtension Stem. Both Femoral Component, PF+ and Tibial Baseplate, PF+ cancollocate 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 andPosterior Stabilized type. Femoral Component, PF+ is manufactured from castCo-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 toachieve biological fixation.
	• Tibial Baseplate, PF+Tibial Baseplate, PF+ is manufactured from titanium alloy (ASTM F620) whichis forged by titanium alloy bars (ASTM F136). The backside of the subject deviceis coated with Titanium powder (ASTM F1580).
	• Tibial Extension StemTibial Extension Stem is collocated with tibial baseplate. The subject device ismade of titanium alloy conforming to ASTM F136.
Indications for use	U2 Total Knee System - PF+ is indicated in knee arthroplasty for reduction orrelief of pain and/or improved knee function in skeletally mature patients withsevere knee pain and disability due to rheumatoid arthritis, osteoarthritis, primaryand secondary traumatic arthritis, polyarthritis, collagen disorders, avascularnecrosis of the femoral condyle or pseudogout, posttraumatic loss of jointconfiguration, particularly when there is patellofemoral joint surfaceerosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexiondeformities. This device may also be indicated in the salvage or previouslyfailed surgical attempts or for knee in which satisfactory stability in flexioncannot be obtained at the time of surgery. Femoral Component, PF+, TibialBaseplate, PF+ and Tibial Extension Stem are indicated for both cemented andcementless use.
TechnologicalCharacteristics	The Subject device fundamental scientific principles and technologicalcharacteristics, including: the intended use, material and general design, are the
	same as, or similar to, the primary predicate and the chosen additionalpredicate/reference devices.Summary of the technological characteristics:✓ Intended use: identical✓ Indications for Use, Anatomical sites, operating principles and conditions ofuse are identical✓ No new risks associated to the Subject device compared to those of thepredicate devices.
	✓ Verification activities on Subject devices demonstrated equivalent safety andeffectiveness as compared to the predicate devices.
	✓ Material: are identical to the primary predicate.✓ Geometry and size: Sizes of the Subject device are bracketed in size by thepredicates.
✓	Sterilization: identical method as predicates.
	The technological characteristics of the Subject device are substantiallyequivalent to the predicate device(s).
Performance Analysis	Based on the modification items of the design rationale of the Subject device, thefollowing tests were conducted to evaluate the safety and effectiveness of thesubjected device, and the test results indicated that this device is safe andeffective.• Femoral component fatigue test• Tibial baseplate fatigue test• Articulating surface finish of femoral component• Finish of non-articulating surface of tibial baseplate• Microstructure of the modified surface• Mechanical properties of the modified surface• Bacteria endotoxin testing was conducted and met the endotoxin limit asspecified in USP<161>
Conclusion	Based upon equivalences in: intended use, patient population, site of application,conditions of use, operating principles, and the non-clinical performance data,the Subject device has been shown to be safe and effective and to performequivalently as compared to the legally marketed predicate devices.Therefore, the Subject devices are substantially equivalent to the legallymarketed predicate devices.

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U2 Total Knee System, PF+

Regulation Number and Section

§ 888.3565 Knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis.

(a)
Identification. A knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis is a device intended to be implanted to replace a knee joint. The device limits translation and rotation in one or more planes via the geometry of its articulating surfaces. It has no linkage across-the-joint. This generic type of device is designed to achieve biological fixation to bone without the use of bone cement. This identification includes fixed-bearing knee prostheses where the ultra high molecular weight polyethylene tibial bearing is rigidly secured to the metal tibial base plate.(b)
Classification. Class II (special controls). The special control is FDA's guidance: “Class II Special Controls Guidance Document: Knee Joint Patellofemorotibial and Femorotibial Metal/Polymer Porous-Coated Uncemented Prostheses; Guidance for Industry and FDA.” See § 888.1 for the availability of this guidance.