(254 days)
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
| Acceptance Criteria / Performance Metric | Predicate Device (UKNEE® Total Knee System) Performance | U2 Total Knee System Performance | Result |
|---|---|---|---|
| Range of Motion (for daily life needs) | Not explicitly stated (implied to be sufficient) | 135° | Satisfied |
| Constraint | Baseline | Slightly more constraint than predicate device | Met/Exceeded |
| Femorotibial Joint Contact Area | Baseline | Similar or greater than predicate device | Met/Exceeded |
| Patellofemoral Joint Contact Area | Baseline | Similar or greater than predicate device | Met/Exceeded |
| Tibial Insert and Tray Locking (Anteroposterior motion at 100N load) | Baseline (implied higher motion) | Less than the predicate device | Exceeded |
| Tibial Baseplate Fatigue Properties (Cyclic Test: 200N-2.0KN, 5 million cycles) | Not explicitly stated (implied to be acceptable) | No fracture on the tibial baseplate | Satisfied |
| Beaded Porous Coating Static Tensile Strength | Not explicitly stated (implied to be acceptable) | Endured 5,000 psi min | Satisfied |
| Beaded Porous Coating Shear Strength | Not explicitly stated (implied to be acceptable) | More than 20 MPa | Satisfied |
| Beaded Porous Coating Volume Porosity | Not explicitly stated (implied to be within range) | Between 30 and 70 percent | Satisfied |
| Beaded Porous Coating Average Pore Size | Not explicitly stated (implied to be within range) | Between 100 and 1000 microns | Satisfied |
| Beaded Porous Coating Thickness | Not explicitly stated (implied to be within range) | Between 1,000 and 1,300 microns (Note: This is inconsistent. Document states "1.0 +0/+0.3 mm" which is 1000-1300 micrometers on page 1, and "1,000 and 1,300 microns" on page 3. Assuming they are referring to the same thing.) | Satisfied |
| Material Property Requirements | ASTM standards met for predicate materials | Meet the property requirements of the ASTM standards associated with each material | Satisfied |
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.
§ 888.3560 Knee joint patellofemorotibial polymer/metal/polymer semi-constrained cemented prosthesis.
(a)
Identification. A knee joint patellofemorotibial polymer/metal/polymer semi-constrained cemented 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 includes prostheses that have a femoral component made of alloys, such as cobalt-chromium-molybdenum, and a tibial component or components and a retropatellar resurfacing component made of ultra-high molecular weight polyethylene. This generic type of device is limited to those prostheses intended for use with bone cement (§ 888.3027).(b)
Classification. Class II.