(20 days)
The intended use of the modified tibial bearing inserts is identical to that of the unmodified tibial bearing inserts. As with the predicate tibial bearing inserts, the modified tibial bearing inserts are single use devices. They are intended for mating with commercially available Osteonics® Tibial Trays and corresponding posteriorly stabilized femoral and patellar components. The Osteonics® Scorpio™ Posteriorly Stabilized Total Knee Components are intended for cemented fixation. Specific indications for use are as follows:
- Painful, disabling joint disease of the knee resulting from: degenerative arthritis, . rheumatoid arthritis or post-traumatic arthritis.
- Post-traumatic loss of knee joint configuration and function.
- Moderate varus, valgus, or flexion deformity in which the ligamentous structures can be returned to adequate function and stability.
- Revision of previous unsuccessful knee replacement or other procedure.
- Ligamentous instability requiring implant bearing surface geometries with increased constraint.
- Absent or non-functioning posterior cruciate ligament.
The Osteonics® Scorpio™ Total Knee Relaxed Back P/S Tibial Bearing Insert is a modification of the predicate Osteonics® Scorpio™ Total Knee Posteriorly Stabilized Tibial Bearing Insert. The modification involves increasing the posterior radius of the tibial bearing insert to a value of six inches as compared to three inches for the standard Scorpio™ family of tibial bearing inserts. This modification is designed to allow the femur to reach deeper flexion angles by further resisting femoro-tibial distraction and increase ligament tension in the deep flexion range. All other design features of the modified Scorpio™ design tibial bearing insert will remain unchanged. The sizes and UHMWPE thicknesses of the modified tibial bearing inserts will be identical to the predicate tibial bearing insert design.
The provided document describes a medical device modification (K991461 Osteonics® Scorpio™ Total Knee Relaxed Back P/S Tibial Bearing Insert) and its substantial equivalence to a predicate device, rather than a study with acceptance criteria and performance metrics in the way one would typically quantify for AI/software-as-a-medical-device (SaMD).
Therefore, many of the requested elements (sample sizes, expert qualifications, MRMC studies, standalone performance, training set details) are not applicable to this type of device modification submission. This document focuses on demonstrating that a physical modification to an existing, cleared device does not raise new questions of safety or effectiveness.
Here's a breakdown of the available information, highlighting what is present and what is not applicable:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not present quantitative acceptance criteria or performance metrics in a tabular format as would be seen for a diagnostic or AI device. Instead, it relies on demonstrating substantial equivalence to a predicate device.
| Acceptance Criterion (Implicit for Substantial Equivalence) | Reported Device Performance (as demonstrated by the modification) |
|---|---|
| Safety and Effectiveness maintained: The modified device should be as safe and effective as the predicate device. | "All other design features of the modified Scorpio™ design tibial bearing insert will remain unchanged." "The sizes and UHMWPE thicknesses of the modified tibial bearing inserts will be identical to the predicate tibial bearing insert design." "A Risk Analysis and R & D Testing have been performed to demonstrate the substantial equivalence of this tibial bearing insert design to the predicate tibial bearing insert design." |
| Intended Use maintained: The modification should not change the intended use of the device. | "The intended use of the modified tibial bearing inserts is identical to that of the unmodified tibial bearing inserts." |
| Technological Characteristics (except the specified modification) are equivalent: Materials, manufacturing, and other design features should remain substantially similar. | "All features of the Osteonics® Scorpio™ Total Knee Relaxed Back P/S Tibial Bearing Insert are unchanged with the exception of 1) the change posterior radius of the tibial bearing insert from three inches to six inches. All other design features, materials and manufacturing methods will remain unchanged." |
2. Sample size used for the test set and the data provenance
- Not Applicable. This is a physical device modification, not a software or diagnostic algorithm undergoing testing on a "test set" of data. The "testing" referred to ("R & D Testing") would be mechanical, material, or bench testing rather than performance on a clinical data set.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
- Not Applicable. See point 2.
4. Adjudication method for the test set
- Not Applicable. See point 2.
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 implant, not an AI or diagnostic device that requires human interpretation.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
- Not Applicable. This is a physical implant, not a standalone algorithm.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- Not Applicable. The "ground truth" for this device modification is assessed through engineering principles, material compatibility, biomechanical testing, and comparison to the predicate device's established safety and performance profile over time. The document states a "Risk Analysis and R & D Testing" were performed to demonstrate substantial equivalence.
8. The sample size for the training set
- Not Applicable. This is not an AI/ML device requiring a training set.
9. How the ground truth for the training set was established
- Not Applicable. This is not an AI/ML device requiring a training set.
Summary of the Study (Device Modification)
The "study" in this context is the submission for a Special 510(k), which is specifically for modifications to a manufacturer's own legally marketed device. The goal is to demonstrate that the change does not significantly affect the safety or effectiveness of the device.
Device Modification:
- Description: The modification involves increasing the posterior radius of the tibial bearing insert from three inches (predicate) to six inches.
- Purpose of Modification: To allow the femur to reach deeper flexion angles by further resisting femoro-tibial distraction and increasing ligament tension in the deep flexion range.
- Unchanged Features: All other design features, sizes, UHMWPE thicknesses, materials, and manufacturing methods remain identical to the predicate device.
- Intended Use: Remains identical to the predicate device.
Proof of Meeting (Implicit) Acceptance Criteria (Substantial Equivalence):
- The manufacturer performed a Risk Analysis and R&D Testing to demonstrate substantial equivalence. While details of these tests are not provided in this summary, they would typically involve bench testing (e.g., wear testing, fatigue testing, mechanical strength) to ensure the modified design performs comparably or better than the predicate, especially regarding the changed radius.
- The FDA's decision to clear the device implies they accepted these demonstrations of substantial equivalence, ensuring the modified device meets the general controls provisions of the Act for safety and effectiveness. The limitations imposed by the FDA (cemented use only, minimum polyethylene thickness) indicate specific areas they wanted clarified and restricted to ensure continued safety.
§ 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.