(172 days)
Disposable cement spacer molds are indicated for use to mold a temporary total knee replacement (TKR) for skeletally mature patients undergoing a two-stage procedure due to a septic process. The molded temporary knee prosthesis is indicated for an implantation period of 180 days or less. Because of inherent mechanical limitations of the device material (gentamicin/polymethylmethacrylate) and mobility limitations, the molded temporary prosthesis is only indicated for patients who will consistently use traditional mobility assist devices (e.g. crutches, walkers) throughout the implant period.
The femoral cement spacer molds are offered in four sizes (60mm, 65mm, 70mm & 75mm). The tibial cement spacer molds are offered in four sizes (65mm, 70mm, 75mm & 80mm). The disposable cement spacer molds are not implanted. The molds are filled with polymethylmethacrylate/gentamicin bone cement, or equivalent, either by injecting with a dispenser/gun, or by pouring the prepared cement into the mold. After the cement hardens, the temporary knee prosthesis components are removed from the mold and placed into the joint space. The temporary knee prosthesis remains in place until the second stage of the two-stage procedure is performed to implant a conventional knee joint prosthesis.
The provided 510(k) summary for the "Disposable Cement Spacer Molds for Temporary Knee Prosthesis" does not describe a study that includes acceptance criteria and reported device performance in the typical sense of a diagnostic or AI-powered device.
This device is a Class II surgical tool (mold), not a diagnostic or AI-driven system, and therefore its regulatory submission focuses on demonstrating substantial equivalence to a predicate device through non-clinical testing, rather than clinical efficacy thresholds.
However, I can extract the relevant information concerning the non-clinical testing performed and how it demonstrates "performance" relative to its predicate.
Here's the breakdown based on the information provided:
1. Table of Acceptance Criteria and Reported Device Performance
Given that this is a surgical mold and not a diagnostic device, the "acceptance criteria" are implied by demonstrating equivalence to a predicate device's characteristics.
| Acceptance Criterion (Implied) | Reported Device Performance |
|---|---|
| Equivalent Strength | Demonstrated equivalent strength to the predicate device in a knee joint simulator study. |
| Equivalent Wear Characteristics | Demonstrated equivalent wear characteristics to the predicate device in a knee joint simulator study. |
| Equivalent Gentamicin Release | Elution testing demonstrated equivalent gentamicin release compared to the predicate device. |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: Not explicitly stated as a number of devices tested. The "knee joint simulator" likely involved a set number of test articles (molded prostheses) from both the applicant's device and the predicate. The text states "knee joint simulator... utilizing both the temporary knee prosthesis made with the Biomet disposable cement spacer mold and the Exactech Spacer-K device."
- Data Provenance: This was non-clinical testing (bench testing) performed under controlled laboratory conditions, not on patient data. Therefore, there's no country of origin or retrospective/prospective designation in the typical clinical sense.
3. Number of Experts Used to Establish Ground Truth and Qualifications
Not applicable. Ground truth for a surgical mold is not established by expert clinical consensus. Its effectiveness is based on its physical properties and performance in non-clinical settings, as well as its ability to produce a product (the temporary prosthesis) that mimics a legally marketed equivalent.
4. Adjudication Method for the Test Set
Not applicable, as this was not a clinical study involving human judgment or diagnostic outcomes.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
Not applicable. This device is a mold for producing temporary prostheses, not a diagnostic tool requiring human interpretation or AI assistance.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Not applicable. This is a physical medical device (mold), not an algorithm or AI system.
7. Type of Ground Truth Used
The "ground truth" (or basis for comparison) was the performance of the legally marketed predicate device (Exactech Spacer-K temporary knee prosthesis) in a controlled non-clinical setting. The Biomet mold was deemed acceptable if the temporary prostheses it produced demonstrated equivalent strength, wear characteristics, and gentamicin release to those produced by the predicate device.
8. Sample Size for the Training Set
Not applicable. This is a physical medical device, not a machine learning model requiring a training set.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no training set for this type of device.
§ 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.