(117 days)
The iTotal® CR Knee Replacement System 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.
The implant is intended for cemented use only.
The iTotal Cruciate Retaining 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 and related instrumentation are designed, that best meet 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 that are manufactured from UHMWPE. The patellar component is also manufactured from UHMWPE.
ConforMIS is proposing a line extension of the current iTotal CR Knee Replacement System. The proposed line extension consists of providing tibial inserts and patellae made from a highly cross linked Vitamin E infused polyethylene (iPoly XE) similar to the predicate Biomet E-Poly™ Tibial Bearings (K080528) and the DJO Surgical Highly Cross-Linked Vitamin E UHMWPE Tibial Insert and Patella (K113756, K103223, K091956).
The iPoly XE tibial inserts and patellae will be manufactured from ultra high molecular weight polyethylene (UHMWPE) that is blended with Vitamin E (alpha-tocopherol), compression molded and then highly crosslinked. Other than the material, the iPoly XE Tibial inserts are identical in design to those cleared for the iTotal CR KRS via K120316. The iPoly XE patellae are also identical in design to those cleared via K112780.
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 acceptance criteria and study details for the ConforMIS iTotal® Cruciate Retaining Knee Replacement System with iPoly XE™ Tibial Inserts and patellae are outlined below, based on the provided 510(k) summary (K122870).
1. Table of Acceptance Criteria and Reported Device Performance
The submission focuses on demonstrating substantial equivalence to predicate devices through non-clinical laboratory testing. The "acceptance criteria" are implied by the successful performance of these tests, indicating that the device's material properties and performance characteristics are comparable to or improved over the predicates, particularly regarding wear reduction.
| Property / Characteristic Type | Acceptance Criteria (Implied by Substantial Equivalence) | Reported Device Performance |
|---|---|---|
| Biocompatibility | Meets established biocompatibility standards for implantable devices (e.g., ISO 10993 series relevant tests). | All tested characteristics (Cytotoxicity, Sensitization, Intracutaneous Irritation, Systemic Toxicity, Material Mediated Pyrogenicity, Sub Chronic Toxicity, Genotoxicity, Muscle Implantation) demonstrated that the device is safe, indicating compliance with biocompatibility requirements. |
| Physical and Mechanical Properties | Comparable strength, fatigue resistance, impact resistance, tensile properties, and compressive modulus to predicate devices, ensuring structural integrity and functional performance. | Tests (Small Punch Test, Fatigue Crack Growth Test, Izod Impact Test, Static Tensile Test, Compressive Modulus Test) showed performance suitable for the intended use and comparable to predicate devices. |
| Chemical Properties | Comparable chemical composition and material characteristics (e.g., cross-link density, vitamin E content, oxidation resistance) to predicate vitamin E infused UHMWPE materials. | Tests (Scanning Electron Microscopy analysis, Differential Scanning Calorimetry analysis, Free Radical Content, Oxidization Index, Extraction analysis, Residue on extraction, Uniformity of radiation dose, Cross-link Density, Vitamin E Content, Ash Content, Environmental Stress Cracking) confirmed the material properties, including the successful integration of Vitamin E and cross-linking as described. |
| Performance Testing | Comparable or improved wear performance, contact area/stress, and mechanical integrity (interlock strength, patella subluxation resistance) compared to predicate devices. | - Wear Testing: In-vitro knee simulator wear testing demonstrated a significant gravimetric wear reduction for the iTotal CR KRS with iPoly XE compared to the iTotal CR KRS with conventional polyethylene tibial inserts. (Note: The submission explicitly states "The results of in-vitro wear simulation testing have not been proven to quantitatively predict clinical wear performance.") |
- Other Performance Tests: Tibiofemoral Contact Area/Stress, Strength of Tibial interlock, Patella Shear Test, Patella Tensile Test, Patellofemoral Contact Area/Stress Test, Wear Testing under abrasive conditions, Analysis of wear debris were conducted and results supported substantial equivalence. |
| Electromagnetic Compatibility | Compatibility with MRI environments, ensuring patient safety and device integrity during MRI scans. | Evaluation demonstrated the safety and compatibility of the iTotal CR Knee Replacement System within the MRI Environment. |
The study concluded that: "All testing has demonstrated the device is substantially equivalent to the predicate devices." and specifically, "Test results demonstrated that the device is safe and can be considered substantially equivalent to the predicate device for the intended use."
2. Sample Size Used for the Test Set and Data Provenance
The provided summary does not explicitly state the specific sample sizes for each non-clinical laboratory test (e.g., number of samples for wear testing, mechanical testing). These are typically detailed in the full test reports, which are not included in the 510(k) summary.
- Data Provenance: The data is retrospective in the sense that it's laboratory testing conducted on the manufactured device components. The data origin is from the manufacturer's (ConforMIS Inc.) internal testing or contracted testing laboratories. There is no mention of country of origin for the data provided directly in this summary.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of information is not applicable to this submission. The device is a medical implant (knee replacement system), and the testing performed is non-clinical laboratory testing (material properties, mechanical performance, wear simulation, biocompatibility). Clinical performance is not evaluated in this submission for substantial equivalence. "Ground truth" in the context of expert consensus or pathology is typically relevant for diagnostic AI/imaging devices.
4. Adjudication Method for the Test Set
This is not applicable as the evaluation is based on objective laboratory data against predefined engineering and material standards, not expert adjudication of subjective assessments.
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
This is not applicable. This is a submission for a knee implant, not an AI-assisted diagnostic or clinical decision support device. Therefore, no MRMC studies or AI-related effectiveness studies were part of this 510(k).
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
This is not applicable. This submission is for a knee implant. While the device utilizes patient-specific design based on imaging (CT or MR scans) and "proprietary and off the shelf software" for design, the submission does not describe this software as an "algorithm" in the context of standalone diagnostic or assistive AI performance. The focus is on the physical implant's material and mechanical properties, not the performance of the design software as a medical device in itself.
7. The Type of Ground Truth Used
The "ground truth" for the non-clinical laboratory testing is established by:
- Known material specifications and standards: e.g., for UHMWPE, Vitamin E content, CoCrMo alloy properties.
- Industry standards and test methods: e.g., ISO 14243 for wear testing, ISO 10993 for biocompatibility.
- Pre-defined engineering and design requirements: Ensuring the device meets its functional criteria (e.g., interlock strength, contact stress).
- Comparisons to predicate devices: The "ground truth" for determining substantial equivalence is largely the established safety and effectiveness of the legally marketed predicate devices through comparable test results.
8. The Sample Size for the Training Set
This is not applicable. There is no "training set" in the context of AI/machine learning for this submission. The device design process involves using patient imaging data, but that's for individual patient-specific device creation, not for training a generalizable AI model described in this summary.
9. How the Ground Truth for the Training Set was Established
This is not applicable for the same reasons as point 8.
§ 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.