Orthopedic Device Metallic and Calcium Phosphate Coatings: Testing and Characterization Requirements (DRAFT)
This guidance applies to Class II and Class III orthopedic devices with metallic and/or calcium phosphate coatings. It specifically covers: - Metallic coatings manufactured using thermal spray, sintering, vapor deposition, additive manufacturing or other methods - Calcium phosphate coatings manufactured by plasma spray, solution precipitation, electrochemical deposition or other methods - Dual coatings combining both metallic and calcium phosphate layers The guidance does not cover other types of coatings (ceramic, other calcium-based) or surface modifications (etching, anodizing). Drug/biologic characterization is also out of scope.
This is a draft guidance. Not for implementation.
What You Need to Know? 👇
What are the key testing requirements for metallic coatings on orthopedic devices?
Metallic coatings require chemical composition analysis, microstructural characterization (thickness, porosity, pore size), and mechanical testing including static tensile strength (≥22 MPa), shear fatigue strength (≥10 MPa for 10⁷ cycles), and Taber abrasion resistance (<65 mg loss over 100 cycles).
Which sterilization method is recommended for calcium phosphate coated devices?
Gamma radiation sterilization is recommended for all calcium phosphate coated devices based on extensive clinical history and non-clinical data showing no negative impact on coating properties. Other sterilization methods require supporting data demonstrating no adverse effects on coating characteristics.
What biocompatibility endpoints must be addressed for orthopedic implant coatings?
For long-term tissue/bone contact devices, required endpoints include cytotoxicity, sensitization, irritation, acute systemic toxicity, material-mediated pyrogenicity, subchronic toxicity, genotoxicity, implantation, chronic toxicity, and carcinogenicity per ISO 10993-1 recommendations.
When do coating modifications require a new 510(k) submission?
New 510(k) submissions are required for changes to coating methods/vendors with different properties, addition of coating layers, thickness increases, pore size/porosity modifications, substrate material changes, or surface treatment modifications that significantly alter surface roughness.
What are the specifications for porous coatings intended for biological fixation?
Porous coatings for biological fixation should have 30-70% volume porosity, 100-1,000 micron average pore size, interconnecting porosity, and 500-1,500 micron coating thickness per CFR regulations for hip and shoulder prostheses.
What physicochemical analyses are required for plasma-sprayed calcium phosphate coatings?
Required analyses include elemental analysis (calcium, phosphorus, impurities), phase analysis via X-ray diffraction, Ca/P ratio determination (1.61-1.76 range), infrared structural analysis for molecular characterization, and dissolution rate testing at pH 7.4 and 5.5.
What You Need to Do 👇
Recommended Actions
- Determine if device requires clinical data based on novelty and risk assessment
- Develop comprehensive coating characterization plan including:
- Physical/chemical properties testing
- Mechanical integrity testing
- Biocompatibility evaluation
- Sterility validation
- Establish specifications and acceptance criteria for coating properties
- Validate shelf life and packaging system
- Prepare labeling with appropriate indications and limitations
- Determine if changes to existing devices require new 510(k) submission
- Consider pre-submission consultation for novel technologies or testing approaches
- Document all testing and validation in format suitable for regulatory submission
- Maintain design history file with complete test reports and justifications
- Monitor post-market performance to confirm coating safety and effectiveness
Key Considerations
Clinical testing
- Generally unnecessary except for novel technologies or when bench/animal testing raises concerns
- IDE requirements apply if clinical investigation is needed
- Real-world data may be acceptable in some cases
Non-clinical testing
- Coating description including name, method, materials, structure, location
- Mechanical testing for coating integrity and adhesion
- Microstructural characterization
- Chemical analysis and phase composition
- Dissolution rate testing for calcium phosphate coatings
- Substrate/device testing to evaluate coating process effects
Labelling
- Must specify cementless implantation for calcium phosphate coated joint arthroplasty
- Biological fixation claims only allowed for porous coatings meeting specific criteria
- “Nano” claims require supporting characterization data
Biocompatibility
- Required for all patient-contacting materials including substrate and coating
- Testing based on implant devices with tissue/bone contact and long-term duration
- Additional evaluation needed for novel coatings without predicate devices
Safety
- Sterility validation required
- Pyrogenicity testing needed
- Shelf life and packaging validation required
Other considerations
- Animal studies generally unnecessary except for novel technologies
- Changes requiring new 510(k): different coating method/vendor, additional layers, substrate material changes
- Changes not requiring new 510(k): material supplier changes within specs, reduced coating thickness within specs
Relevant Guidances 🔗
- Use of ISO 10993-1 for Biological Evaluation and Testing of Medical Devices
- Testing Requirements for Orthopedic Implants with Modified Metallic Bone-Interface Surfaces
- Recommended Format and Content for Non-Clinical Bench Performance Testing in Medical Device Premarket Submissions
- Content and Decision-Making Process for 510k Submissions: Determining Substantial Equivalence
- Deciding When to Submit a New 510k for Changes to an Existing Medical Device
Related references and norms 📂
- ASTM F1854: Standard test method for stereological evaluation of porous coatings on medical implants
- ASTM F1147: Standard test method for tension testing of calcium phosphate and metallic coatings
- ASTM F1160: Standard test method for shear and bending fatigue testing of calcium phosphate and metallic coatings
- ASTM F1978: Standard test method for measuring abrasion resistance of metallic thermal spray coatings
- ISO 13779-1: Implants for surgery — Hydroxyapatite — Part 1: Ceramic hydroxyapatite
- ISO 13779-2: Implants for surgery — Hydroxyapatite — Part 2: Thermally sprayed coatings of hydroxyapatite
- ISO 11607-1: Packaging for terminally sterilized medical devices — Part 1: Requirements for materials, sterile barrier systems and packaging
- ISO 10993-1: Biological evaluation of medical devices — Part 1: Evaluation and testing within a risk management process