(98 days)
The iTotal® CR Knee Replacement System (KRS) is intended for use as a total knee replacement in patients with knee joint pain and disability whose conditions cannot be solely addressed by the use of a prosthetic device that treats only one or two of the three knee compartments, such as a unicondylar, patellofemoral or bicompartmental prosthesis.
The Indications for Use include:
- · Painful joint disease due to osteoarthritis, traumatic arthritis, rheumatoid arthritis or osteonecrosis of the knee.
- · Post traumatic loss of joint function.
- · Moderate varus, valgus or flexion deformity in which the ligamentous structures can be returned to adequate function and stability.
- · Failed osteotomies, hemiarthroplasties, and unicondylar, patellofemoral or bicompartmental implants.
- · Revision procedures provided that anatomic landmarks necessary for alignment and positioning of the implant are identifiable on patient imaging scans.
This implant is intended for cemented use only.
The iTotal® CR Knee Replacement System (hereafter referred to as the "iTotal CR KRS") is a patient specific tricompartmental faceted posterior cruciate ligament (PCL) retaining knee replacement system. The iTotal® CR KRS is a semi-constrained, cemented knee implant which consists of a femoral, tibial, and patellar component.
Using patient imaging (either CT or MR scans) and a combination of proprietary and off the shelf software a patient specific implant is designed, that best meets the geometric and anatomic requirements of the specific patient. The femoral component is manufactured from cobalt chromium molybdenum ("CoCrMo") alloy. The tibial component includes a metal tray manufactured from CoCrMo alloy and either one or two polyethylene inserts. The polyethylene inserts may be manufactured from either UHMWPE or a highly cross-linked Vitamin E infused polyethylene (iPoly XE™) The patellar component is also manufactured from either UHMWPE or from a highly cross-linked Vitamin E infused polyethylene (iPoly XE™).
For user convenience, and similar to the predicate iTotal CR KRS, accessory orthopedic manual surgical instruments designed for use with the modified iTotal CR KRS are provided to assist with implantation. The ancillary instruments are provided sterile and for single-use only. These patient specific instruments are provided to assist in the positioning of total knee replacement components intra-operatively and in guiding the cutting of bone.
The function and general design features of the patient specific implants and ancillary instruments remain similar to those described in the predicate 510(k)'s K131467 and K131019.
Here's an analysis of the acceptance criteria and study information for the ConforMIS iTotal® CR Knee Replacement System (K140423), based on the provided text:
Acceptance Criteria and Device Performance for ConforMIS iTotal® CR Knee Replacement System (K140423)
It's important to note that this 510(k) summary primarily focuses on demonstrating substantial equivalence to a predicate device, rather than defining specific numerical performance acceptance criteria in the way one might see for a diagnostic AI device. The "performance" here is demonstrating that the modified device is as safe and effective as the predicate device.
1. Table of Acceptance Criteria and Reported Device Performance
Given the nature of this submission (a 510(k) for a modified knee replacement system), the acceptance criteria are largely qualitative, centered around demonstrating equivalence and safety. The performance is assessed through verification and validation of changes.
| Acceptance Criteria Category | Specific Criteria/Tests | Reported Device Performance (as demonstrated by testing) |
|---|---|---|
| Substantial Equivalence | Comparison of Indications for Use, Principle of Operation, Product Classification, Components & Materials, Design, Patient Matched status, and Instrumentation with Predicate Device. | The modified iTotal CR KRS (this submission) shares identical Indications for Use, Principle of Operation, Product Classification, Components & Materials, Design, Patient Matched status, and Instrumentation with the predicate iTotal CR KRS. Minor software version updates are the primary difference. |
| Software Functionality | Software verification and validation testing for proprietary software: iTotalWorks (v5.0), iTotal FemJigs (v2.0), iTotalTib (v2.0), iTotal TibJigs (v1.0), iTotal iView (v2.0). | Detailed software description and software verification and validation testing were performed for all proprietary software, demonstrating its functionality and safety. |
| Device Design & Function | Design validation via cadaveric testing. | Cadaveric testing was performed, demonstrating the safety and effectiveness of the device's design. |
| Overall Safety & Performance | Demonstration that the device is safe and can be considered substantially equivalent to the predicate device for its intended use. | Non-clinical laboratory testing (software V&V, cadaveric testing) demonstrated the device is safe and substantially equivalent to the predicate device. |
2. Sample Size Used for the Test Set and Data Provenance
The provided document does not specify a distinct "test set" in the context of typical AI/ML model evaluation with granular sample sizes.
- Software Verification and Validation: Performed for specific software versions (iTotalWorks v5.0, iTotal FemJigs v2.0, iTotalTib v2.0, iTotal TibJigs v1.0, iTotal iView v2.0). The sample size for these tests is not explicitly stated in terms of patient cases or specific data points, but rather implies a thorough testing regimen for the software itself.
- Cadaveric Testing: This typically involves a very small number of specimens. The exact number of cadavers used is not specified, but this is a common method for validating surgical instrument fit and implant placement.
- Data Provenance: Not applicable in the context of patient data for model training/testing as this is a medical device (knee replacement system) and associated software for design and implantation, not a diagnostic AI algorithm analyzing patient data. The "data" here relates to the software itself and the physical device.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications of Those Experts
Not applicable for this submission. The ground truth for this device revolves around established engineering principles, biomechanical performance, and surgical accuracy. The "ground truth" for cadaveric testing would be the precise fit and alignment of the implant components as assessed by experts (e.g., orthopedic surgeons, biomedical engineers), but the specific number or qualifications are not detailed.
4. Adjudication Method for the Test Set
Not applicable. There's no indication of multiple readers reviewing outputs that would require an adjudication method. Verification and validation are typically performed against pre-defined specifications and expected outcomes.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not performed. This type of study is more common for diagnostic imaging AI systems where human readers interpret medical images with and without AI assistance. This submission is for a knee replacement system and its associated planning software, not a diagnostic AI.
6. Standalone (Algorithm Only) Performance Study
Yes, in a sense, standalone performance was assessed through the "Software verification and validation testing of proprietary software" for each component of the iTotal CR KRS system (iTotalWorks, iTotal FemJigs, iTotalTib, iTotal TibJigs, iTotal iView). This means the algorithms within these software packages were tested for their intended function (e.g., design generation, jig creation, surgical planning) independent of human intervention in the evaluation process. The cadaveric testing also validates the output of these algorithms in a realistic, non-human patient setting prior to clinical use.
7. Type of Ground Truth Used
- Software Verification and Validation: The "ground truth" is defined by the software's functional requirements, design specifications, and expected outputs. This includes accuracy of calculations, proper generation of designs, and adherence to engineering principles.
- Cadaveric Testing: The "ground truth" is the optimal anatomical fit and alignment of the implant components, typically measured against surgical goals and expected outcomes derived from anatomical studies and surgical best practices.
8. Sample Size for the Training Set
Not applicable. This device is not an AI/ML system that "learns" from a training set in the typical sense. The software involved in designing patient-specific implants is based on algorithms and models derived from extensive anatomical data and biomechanical principles, but there is no explicitly defined "training set" of patient data in the context of machine learning. The software uses patient-specific imaging (CT or MR scans) to design the implant, rather than being "trained" on a large dataset of patient images to develop its core functionality.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there wasn't a "training set" in the machine learning sense. The underlying principles for the software's algorithms would have been established through biomechanical research, anatomical studies, engineering design principles, and clinical experience, not through a labeled dataset for AI model training.
§ 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.