(210 days)
Limb salvage surgery is indicated for cemented procedures where radical resection and replacement of the distal femur and/or proximal tibia is required with the following conditions:
- patients suffering from severe arthropathy of the knee that does not respond to any conservative therapy or better alternative surgical treatment;
- surgical intervention for severe trauma, revision knee arthroplasties, and/or oncology indications.
- metastatic diseases (e.g., osteosarcomas, chondrosarcomas, gaint cell tumors, bone tumors)
The REPIPHYSIS™ Prosthesis is custom assembled for each patient. The REPIPHYSIS™ is implanted the same way as any other joint replacement device using non-allergic, standard materials that have been tested in biological situations. The REPIPHYSIS™ Limb Salvage Prosthesis Kit consists of the following components: Distal Hinge Femur, Tibial Base, Axial Bushing, Axial Pin. The REPIPHYSIS™ prosthesis uses an external electro-magnetic transmitter to activate the implant lengthening mechanism. The REPIPHYSIS Transmitter Unit operates by producing an electrical current in an inductor coil, which in turn generates a strong electro-magnetic field in the vicinity of the coil. When an electrically conductive material is placed within this electro-magnetic field, an electrical current is induced in the conductive material. If the proper conditions are established, this electrical current is sufficient to cause significant heating in this material. The REPIPHYSIS™ prosthesis consists of two tubes with a spring mechanism contained in the larger tube. It is maintained compressed by a polyacetal locking mechanism. One tube is connected to the stem of the implant, and the second comprises the hinge portion of the hinge prosthesis. The uninvolved side of the joint is minimally resurfaced with a press-fit stem to attempt to preserve function of the non-involved growth plate. Expansion is achieved via exposure to an external electromagnetic field around the extremity. The coil transmits an electromagnetic field around the implant in the vicinity of the v-shaped flange of the spring housing tube. This generates an electrical current within the flange of the spring housing tube and is focused on the receiving antennae within the implant itself. This antenna is heated by the electromagnetic field. The heated element softens the surrounding polyacetal locking mechanism, which allows the spring expansion. The spring expansion pushes the two tubes apart from each other, thus lengthening the overall length of the leg.
This document is a 510(k) Summary of Safety and Effectiveness for the REPIPHYSIS™ Limb Salvage System. It focuses on establishing substantial equivalence to previously cleared devices rather than providing a detailed study proving the device meets specific acceptance criteria with quantifiable performance metrics.
Therefore, many of the requested details about acceptance criteria, study design, and performance metrics are not present in this type of regulatory submission. The document primarily describes the device, its intended use, and argues for its substantial equivalence based on materials, design, and testing results without providing the specifics of those tests or their acceptance criteria in the format requested.
Here's an attempt to answer the questions based only on the provided text, indicating when the information is not available:
1. A table of acceptance criteria and the reported device performance
Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Not Explicitly Stated in Document) | Reported Device Performance (From Document) |
|---|---|
| Not explicitly stated. The document focuses on substantial equivalence to predicate devices, implying performance comparable to legally marketed devices. | The REPIPHYSIS™ Limb Salvage System's safety and effectiveness are "adequately supported by the substantial equivalence information, materials data, and testing results provided within the Premarket Notification." |
Specific, quantifiable performance metrics (e.g., probability of failure, mechanical integrity, accuracy of lengthening to within a certain tolerance, biocompatibility test results with specific acceptance limits, etc.) are NOT detailed in this summary. The summary highlights the mechanism of lengthening and implies functionality.
2. Sample sized used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)
- Sample Size for Test Set: Not specified. This document refers to "testing results" and "materials data" but does not detail the sample sizes for any specific tests or studies.
- Data Provenance: The document states that the REPIPHYSIS™ Limb Salvage System was previously named the Phenix Growing Prosthesis and that "More than 100 patients have been treated with Phenix Growing Prosthesis in the last 20 years." This suggests some level of historical clinical experience, likely retrospective, originating from France ("designed in France in the early 1980s"). However, it's not explicitly stated if this patient data constitutes a "test set" for the current 510(k) submission or if it was used to establish performance against acceptance criteria.
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)
Not specified. The document does not describe a clinical study or expert-based ground truth establishment process for a "test set" in the context of device performance evaluation.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set
Not specified. No adjudication method is mentioned as there is no described clinical study requiring such a process for a test set.
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
No. The document describes a medical device (an implantable prosthesis) for limb salvage, not an AI-assisted diagnostic or interpretative tool. Therefore, an MRMC comparative effectiveness study involving human readers and AI assistance is not applicable and not mentioned.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
Not applicable. This device is not an algorithm or software requiring standalone performance testing. It is a physical implantable device.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)
- The document implies that the safety and effectiveness are supported by "substantial equivalence information, materials data, and testing results." This suggests a reliance on engineering testing, material characterization, and potentially clinical outcomes data from the predicate device (Phenix Growing Prosthesis).
- The "more than 100 patients treated with Phenix Growing Prosthesis" likely provided outcomes data to support the overall safety and effectiveness indirectly, but the specific metrics and how they constitute "ground truth" for the current submission are not detailed.
- The "Indications Statement" uses terms like "patients suffering from severe arthropathy... that does not respond to any conservative therapy or better alternative surgical treatment," and "surgical intervention for severe trauma, revision knee arthroplasties, and/or oncology indications," which imply clinical diagnosis and established medical conditions as the basis for using the device.
8. The sample size for the training set
Not applicable. This device is not an AI/ML algorithm that requires a "training set."
9. How the ground truth for the training set was established
Not applicable, as there is no "training set" for this device.
§ 888.3510 Knee joint femorotibial metal/polymer constrained cemented prosthesis.
(a)
Identification. A knee joint femorotibial metal/polymer constrained cemented prosthesis is a device intended to be implanted to replace part of a knee joint. The device limits translation or rotation in one or more planes and has components that are linked together or affined. This generic type of device includes prostheses composed of a ball-and-socket joint located between a stemmed femoral and a stemmed tibial component and a runner and track joint between each pair of femoral and tibial condyles. The ball-and-socket joint is composed of a ball at the head of a column rising from the stemmed tibial component. The ball, the column, the tibial plateau, and the stem for fixation of the tibial component are made of an alloy, such as cobalt-chromium-molybdenum. The ball of the tibial component is held within the socket of the femoral component by the femoral component's flat outer surface. The flat outer surface of the tibial component abuts both a reciprocal flat surface within the cavity of the femoral component and flanges on the femoral component designed to prevent distal displacement. The stem of the femoral component is made of an alloy, such as cobalt-chromium-molybdenum, but the socket of the component is made of ultra-high molecular weight polyethylene. The femoral component has metallic runners which align with the ultra-high molecular weight polyethylene tracks that press-fit into the metallic tibial component. The generic class also includes devices whose upper and lower components are linked with a solid bolt passing through a journal bearing of greater radius, permitting some rotation in the transverse plane, a minimal arc of abduction/adduction. This generic type of device is limited to those prostheses intended for use with bone cement (§ 888.3027).(b)
Classification. Class II.