(78 days)
The iTotal® CR Knee Replacement System (iTotal CR 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, patello-femoral or bi-compartmental prosthesis. The indications for use include :
- t 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, hemiarthoplasties, and unicondylar, . patello-femoral or bi-compartmental implants.
The iTotal CR KRS 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. The product design incorporates a bone preserving approach with minimal bone resection of the tibia and femur for the treatment of severe pain and/or disability of a knee damaged by osteoarthritis or trauma.
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 two polyethylene inserts manufactured from UHMWPE. The patellar component is manufactured from UHMWPE.
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 marking of bone before cutting.
The ConforMIS iTotal® CR Knee Replacement System is a patient-specific, semi-constrained, cemented knee implant. This device is intended for total knee replacement in patients suffering from knee joint pain and disability due to conditions like osteoarthritis, traumatic arthritis, rheumatoid arthritis, osteonecrosis, post-traumatic loss of joint function, moderate deformity, or failed prior implants. The submission for this modified device is a 510(k), indicating a claim of substantial equivalence to previously cleared predicate devices.
1. Table of Acceptance Criteria and Reported Device Performance
For this specific 510(k) submission (K120316), the "acceptance criteria" are not explicitly quantified in terms of performance metrics (e.g., accuracy, sensitivity, specificity). Instead, substantial equivalence is established through detailed device description and non-clinical laboratory testing demonstrating that the modifications do not raise new questions of safety or effectiveness compared to the predicate devices. The focus is on ensuring the modified device maintains the same safety and performance characteristics as the legally marketed predicate devices.
| Acceptance Criteria Category | Specific Criteria (Implicit for Substantial Equivalence) | Reported Device Performance |
|---|---|---|
| Material Equivalence | Materials: Femoral, Tibial, Patellar components must be equivalent or validated. | Met: Materials (CoCrMo alloy, UHMWPE) are identical to the predicate device. |
| Design Equivalence | Design: Knee joint patellofemorotibial semi-constrained cemented prosthesis. | Met: Design remains a knee joint patellofemorotibial semi-constrained cemented prosthesis. |
| Principle of Operation | Principle: Cemented use, fixed bearing design. | Met: Operates with cemented use and fixed bearing design. |
| Patient Matched | Patient Matched: Yes | Met: Continues to be patient-matched. |
| Patellar Design/Dimensions | Patellar: Symmetrical, offered in various sizes. | Met: Patellar design is symmetrical and offered in various sizes. |
| Tibial Insert Thickness | Minimum thickness of Tibial Insert (UHMWPE): 6 mm | Met: Minimum tibial insert thickness remains 6 mm. |
| PCL Sparing | Posterior Cruciate Ligament (PCL) Sparing: Yes | Met: Continues to be PCL sparing. |
| Instrumentation | Instrumentation: Patient specific Nylon jigs. | Met: Uses patient specific Nylon jigs. |
| Functional Equivalence | Tibial interlock assembly and disassembly. | Met: Tibial tray/insert interlock assembly/disassembly testing performed. |
| Simulated Use Performance | Cadaveric testing demonstrating functionality and safety. | Met: Cadaveric testing performed. |
The key modification in this submission, as highlighted in the device comparison, is a change in the Tibial Implant interlock design from "Interference fit Anterior lip Tray undercut design" to "Interference fit Anterior lip Double Undercut with Central Spine." The testing performed directly addresses this change.
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size: Not explicitly stated as part of a statistically powered clinical or performance study with a 'test set' in the traditional sense of a machine learning evaluation. For the non-clinical testing performed:
- Cadaveric testing: The specific number of cadaveric specimens used is not provided in the summary.
- Tibial interlock assembly and disassembly testing: The sample size for this mechanical test (e.g., number of interlocks tested) is not specified.
- Data Provenance: Not applicable in this context, as the evaluation primarily involved mechanical and cadaveric bench testing, not patient data for algorithm performance.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This information is not applicable. The device is a physical knee implant system, not a diagnostic or AI-driven decision support system that requires expert-established ground truth on a test set of images or clinical cases. The "ground truth" for the performance of the implant and instruments would be the successful mechanical and functional outcomes observed during the non-clinical testing.
4. Adjudication Method for the Test Set
This information is not applicable. There was no 'test set' that required adjudication by experts in the context of image interpretation or diagnostic performance. The evaluation was based on engineering design, material properties, and mechanical bench testing.
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. An MRMC comparative effectiveness study is not relevant here. This submission is for a physical orthopedic implant and its associated patient-specific instruments, not an AI-assisted diagnostic or image analysis tool.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
This information is not applicable. The device itself is an implant. While patient-specific implants are designed "Using patient imaging (either CT or MR scans) and a combination of proprietary and off the shelf software," the performance evaluation described in this 510(k) summary focuses on the physical implant and instruments, not the standalone performance of the design software. The software's output is a physical design, which then undergoes manufacturing and testing.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
The ground truth used for the non-clinical testing of the physical device would be based on:
- Engineering specifications and standards: For the tibial interlock assembly/disassembly testing, the ground truth would be successful assembly, secure interlock, and resistance to disassembly forces as per design requirements and relevant ASTM standards (implied, not explicitly stated which ones).
- Anatomical and biomechanical integrity: For cadaveric testing, the ground truth would be successful implantation, appropriate fit, alignment, and mechanical stability within the cadaveric knee, consistent with intended surgical outcomes and biomechanical principles.
8. The Sample Size for the Training Set
This information is not applicable. This is not an AI/machine learning submission with a 'training set' in the conventional sense. The "patient-specific implant is designed, that best meets the geometric and anatomic requirements of the specific patient" using proprietary software, but the validation presented here is for the physical device, not the training of the design algorithms.
9. How the Ground Truth for the Training Set Was Established
This information is not applicable as there is no 'training set' for an AI algorithm described in this 510(k) summary for the device itself. The software used for patient-specific design would have its own internal validation processes, but these are not within the scope of this 510(k) document which focuses on the equivalence of the modified physical implant.
§ 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.