(308 days)
The MISHATM Knee System is indicated for patients with medial compartment knee osteoarthritis that have failed to find relief in surgical and/or non-surgical treatment modalities and are still experiencing pain that interferes with activities of daily living and are also unwilling to undergo or ineligible for total knee replacement due to age or absence of advanced osteoarthritis.
The MISHATM Knee System (Figure 1) is a prescription use, extra-capsular knee implant device that is comprised of a tibial base subassembly, femoral base subassembly, absorber subassembly, piston subassembly and locking screws. The tibial base subassembly, femoral base subassembly, piston subassembly and absorber subassembly are provided pre-assembled, and the implant is fixed with locking screws to the medial cortices of the distal femur and proximal tibia to share the loads with the knee joint. The articulating ball-and-sockets allow the implant to accommodate the natural motions of the knee. The implant bases and locking screws are made of titanium alloy and the sockets are CoCrMo alloy. The compressive component of the absorber is made of polycarbonate urethane. The femoral balls, tibial balls, and the internal lining of the absorber are made of carbon-fiber-reinforced polyetheretherketone (CFR-PEEK). The implant comes in two sizes (small and large) and right or left configurations.
The provided text describes the results of a clinical study for the MISHATM Knee System (formerly Calypso Knee System) and various non-clinical (bench) studies to demonstrate its safety and effectiveness.
Here's an analysis of the acceptance criteria and study data based on your request:
1. Table of Acceptance Criteria and Reported Device Performance:
| Acceptance Criteria (Special Controls/Primary Endpoint) | Reported Device Performance and Results |
|---|---|
| Clinical Performance: | Clinical Study Results (Primary Endpoint): |
| Composite Clinical Success (CCS) at 24 months, demonstrating non-inferiority to HTO: |
- Clinically significant improvement ($ \ge $20% change AND $ \ge $10 points) from baseline on WOMAC pain questions in KOOS.
- Clinically significant improvement ($ \ge $20% change AND $ \ge $10 points) from baseline on WOMAC function questions in KOOS.
- Freedom from specified device-related serious adverse events (Deep infection requiring surgical intervention, Damage to adjacent neurovascular or ligament structures necessitating reconstruction, Non-union (HTO only)).
- Maintenance of implant integrity by radiographic assessment.
- (Additional explicit failure criterion: conversion to arthroplasty through 24 months).
Non-inferiority margin (δ) of -0.10. | Achieved.
- Success Rate (Multiple Imputation):
- Calypso Knee group: 83.5%
- Control (HTO) group: 57.2%
- Difference: Calypso Knee group led the Control (HTO) group by 26.3%.
- WOMAC Pain endpoint responder (Crude Observed, N=72): 95.8% (Calypso), 87.9% (HTO)
- WOMAC Function endpoint responder (Crude Observed, N=72): 91.7% (Calypso), 81.3% (HTO)
- No Safety Endpoint Event (CEC) (Crude Observed, N=81): 95.1% (Calypso), 93.8% (HTO)
- No Endpoint Implant Integrity Failure (Crude Observed, N=81): 98.8% (Calypso), 98.8% (HTO)
- No Endpoint Subsequent Surgical Intervention (Crude Observed, N=81): 98.8% (Calypso), 98.8% (HTO)
The study conclusion of non-inferiority was found to be robust through sensitivity analysis for missing data. |
| Non-clinical Performance Testing (Mechanical Function & Durability):
- Absorber Unloading Capacity: Minimum compressive resistance force $ \ge $15 lbs at implanted length.
- Durability, Wear, and Corrosion Resistance:
- Mean polymeric wear rate $ \le $ 6.1 mm³ per one million cycles.
- Mean metallic wear rate $ \le $ 0.004 mm³ per one million cycles.
- Implant materials corrosion resistant.
- Implant functionality maintained for $ \ge $ 10 million simulated gait cycles.
- Static Strength: Will not fracture or break under static compressive load up to 60 lbs. | Bench Study Results:
- Absorber Unloading Capacity: All specimens exceeded the performance criteria ($ \ge $ 15 lbs).
- Durability, Wear, and Corrosion Resistance:
- Mean polymeric wear rate: 0.248 mm³ per one million cycles (Met criterion $ \le $ 6.1).
- Mean metallic wear rate: 0.004 mm³ per one million cycles (Met criterion $ \le $ 0.004).
- No evidence of corrosion after immersion in simulated in vivo environment.
- All test articles remained functional throughout testing (10.3 million cycles).
- Static Strength: All articles survived a static compressive load of 65 lbs without permanent deformation or damage (Met criterion $ \le $ 60 lbs). |
| Biocompatibility: Patient-contacting components demonstrated to be biocompatible. | Achieved. Testing per ISO 10993 series showed:
- Cytotoxicity: Non-cytotoxic
- Irritation: Non-irritant
- Sensitization: Non-sensitizing
- Implantation Effects: Null to minimal reactivity
- Material Mediated Pyrogenicity: Non-pyrogenic
- Systemic Toxicity, Genotoxicity, Carcinogenicity: Non-systemically toxic/genotoxic/carcinogenic (addressed via chemical characterization and toxicological risk assessment).
A 26-week rabbit study showed no local or systemic toxicological effects. |
| Sterility & Pyrogenicity: Performance data support sterility and pyrogenicity of sterile components. | Achieved. - Sterility: Validated to SAL 10-6 using VDMax25 method (ANSI/AAMI/ISO 11137-1/-2).
- Pyrogenicity: All tested devices passed BET with $ \le $ 1 EU/device, meeting ANSI/AAMI ST72:2011. |
| Shelf-life: Performance data support shelf life (sterility, package integrity, device functionality). | Achieved. Non-clinical performance testing confirmed a 5-year shelf-life. |
| MR Compatibility: Safety and compatibility in MR environment. | MR Conditional: - Displacement Force: Translation deflection angle of piral; maximum spatial gradient (D)(4) (bx).
- Torque: No torque.
- Image Artifacts: Maximum artifact size approx. 37 mm from implant with gradient echo pulse sequence (3.0 T MR scanner).
- RF Induced Heating: Maximum temperature rise $
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