Testing Requirements for Metallic Plasma Sprayed Coatings on Orthopedic Implants
This guidance outlines testing requirements and data submission format for manufacturers of metallic plasma sprayed coatings on orthopedic implants who wish to request reconsideration of postmarket surveillance requirements. It specifically focuses on demonstrating that thermal spray coatings have mechanical properties equal to or better than sintered or diffusion bonded porous coatings.
Recommended Actions
- Prepare comprehensive test data package including metallurgical analysis, microstructure characterization, and mechanical testing results
- Ensure all testing meets minimum performance criteria specified in guidance
- Document manufacturing process and any differences between test samples and marketed device
- Prepare detailed test reports with all required elements (test facility, methods, results, etc.)
- Submit data using the Modified Surface Data Forms format provided
- Address any corrosion concerns if using novel material combinations
- Include statistical justification if using fewer than 5 samples for testing
- Submit reconsideration request to FDA’s Postmarket Surveillance Document Mail Center
Key Considerations
Non-clinical testing
- Metallurgical analysis including composition, trace elements, material microstructure
- Microstructure analysis of modified surface layers (thickness, particle size, void characteristics)
- Mechanical testing:
- Shear fatigue strength (10^7 cycles)
- Static shear strength (>20 MPa)
- Static tensile strength (>22 MPa)
- Abrasion resistance (<65 mg loss after 100 cycles)
Biocompatibility
- Corrosion assessment if using new material combinations
- Ion release measurements may be needed
Safety
- Interface examination between coatings and substrate for signs of corrosion
- Post-test failure analysis of specimens
Other considerations
- Manufacturing process description
- Detailed test reports including methods, materials, results
- Statistical adequacy (generally 5 samples unless justified otherwise)
Relevant Guidances
- Testing Requirements for Orthopedic Implants with Modified Metallic Bone-Interface Surfaces
- Orthopedic Device Metallic and Calcium Phosphate Coatings: Testing and Characterization Requirements (Draft)
Related references and norms
- ASTM F1854: Test Method for Stereological Evaluation of Porous Coatings on Medical Implants
- ASTM F1160: Shear and Bending Fatigue Testing of Calcium Phosphate and Porous Metal Coated Medical Coatings
- ASTM F1044: Shear Testing of Porous Metal Coatings
- ASTM F1147: Test Method for Tension Testing of Calcium Phospate and Metallic Coatings
- ASTM F1978-99: Standard Test Method for Measuring Abrasion Resistance of Metallic Thermal Spray Coatings By Using the Taber Abraser
- ASTM C633: Adhesion or Cohesive Strength of Flame-Sprayed Coatings
Original guidance
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