(131 days)
Total knee components are indicated for rheumatoid arthritis; post-traumatic arthritis, osteoarthritis, or degenerative arthritis in older patients whose age, weight, and activity level are compatible with an adequate long-term result; failed osteotomies, unicompartmental replacement, or total knee replacement. Posterior stabilized knee systems are designed for use in patients in primary and revision surgery, where the anterior and posterior cruciate ligaments are absent or incompetent and the collateral ligaments remain intact. Smith & Nephew, Inc. Legion Primary Knee components are indicated for use only with cement and are single use devices.
Subject of this Traditional 510(k) Premarket Notification is a request for long-term in vitro wear claims for the Smith & Nephew, Inc. Legion Primary Knee System. The wear claims will be made for the use of a Legion Primary Oxinium femoral component coupled with a 7.5 Mrad cross-linked polyethylene (XLPE) articular insert. The Legion Primary Knee System consists of existing total knee implant devices, and it is important to note that there are no new total knee components being introduced as a result of this Traditional 510(k) premarket notification.
This document, K093746, is a Traditional 510(k) Premarket Notification for wear claims for the LEGION® Primary Knee System, specifically focusing on the performance of an OXINIUM® femoral component coupled with a 7.5 Mrad cross-linked polyethylene (XLPE) articular insert. It is important to note that this submission does not introduce new total knee components but rather seeks clearance for long-term wear claims for an existing system.
Here's an analysis of the provided information based on your requested criteria:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Implicit for wear claims) | Reported Device Performance |
|---|---|
| Low wear characteristics compared to a control total knee system in long-term laboratory testing. | The OXINIUM®/XLPE bearing couple exhibited low wear characteristics in long-term in vitro laboratory testing. |
Explanation of "Acceptance Criteria": The document doesn't explicitly state numerical acceptance criteria (e.g., "wear must be less than X mg"). Instead, the acceptance is based on demonstrating "low wear characteristics" in comparison to a control device in an in vitro knee simulator. The FDA clearance implies that this comparative performance was deemed acceptable for the wear claims.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: The document does not specify the exact sample size (number of femurs, inserts, or test configurations) used in the in vitro knee simulator wear testing. It refers to "long-term laboratory testing."
- Data Provenance: The data is from in vitro knee simulator wear testing, which is a laboratory setting. There is no information provided about the country of origin, but given the company (Smith & Nephew, Inc.) is based in Memphis, Tennessee, USA, it's reasonable to infer the testing was likely conducted in the US or by a US-based laboratory. The testing is not clinical data; it is in vitro.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications
- Ground Truth Experts: Not applicable. For in vitro mechanical wear testing, "ground truth" is established by the validated testing methodology and measurement of wear (e.g., gravimetric assessment of polyethylene mass loss). Human experts in the sense of clinicians or radiologists are not involved in establishing the "ground truth" for this type of performance testing.
4. Adjudication Method for the Test Set
- Adjudication Method: Not applicable. This refers to the process by which disagreements among human experts in clinical or imaging studies are resolved. As the performance data is from in vitro mechanical testing, there are no human expert judgments or adjudication processes involved in the data generation.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
- MRMC Study: No. An MRMC study involves multiple human readers assessing medical cases, often with and without AI assistance, to measure diagnostic performance. The provided document is about in vitro wear performance of a knee implant, not diagnostic imaging, and does not involve human readers.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
- Standalone Study: Yes, in a conceptual sense within its context. The "device performance" in this submission refers to the in vitro mechanical performance of the knee joint components themselves, operating in a simulator without human intervention. This is a "standalone" evaluation of the mechanical system's wear characteristics. There is no "algorithm" in the traditional sense of an AI model, but the mechanical system's performance is assessed independently.
7. The Type of Ground Truth Used
- Type of Ground Truth: The ground truth for wear performance in this in vitro study is based on direct physical measurement of material loss (e.g., gravimetric wear, linear penetration) from the components during standardized knee simulator testing, according to established test protocols (e.g., ISO standards for knee wear testing, though not explicitly cited here, are typical for such studies). This is considered an objective, quantifiable physical output.
8. The Sample Size for the Training Set
- Training Set Sample Size: Not applicable. This submission concerns in vitro mechanical wear testing of a physical device, not an AI/ML algorithm that requires a "training set."
9. How the Ground Truth for the Training Set Was Established
- Training Set Ground Truth: Not applicable, as there is no training set for this type of device performance evaluation.
§ 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.