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Testing Requirements for Orthopedic Implants with Modified Metallic Bone-Interface Surfaces

This guidance focuses on testing requirements for orthopedic implants with modified metallic surfaces that interface with bone or bone cement. It specifically addresses surface treatments aimed at improving implant fixation, excluding interfaces between prosthetic parts, articulating surfaces, calcium phosphate coatings, and biodegradable materials.

  1. Determine if the surface modification falls under the limited scope (beaded/sintered cobalt-chrome or titanium coatings)
  2. Develop comprehensive test plan covering all required mechanical and biological testing
  3. Prepare detailed documentation of manufacturing processes
  4. Conduct metallurgical and microstructural analysis
  5. Perform required mechanical testing (fatigue, shear, tensile, abrasion)
  6. Complete biocompatibility testing program
  7. Gather available clinical data
  8. Organize data according to the Modified Surface Data Forms format
  9. Prepare detailed test reports with complete methodology and raw data
  10. Consider additional testing requirements if the surface modification is novel or has limited clinical history

Key Considerations

Clinical testing

  • Clinical data summary required for devices with modified surfaces
  • Data should include information on loosening, radiographic evidence of bone/fibrous tissue ingrowth, surface coating particulate migration, and surface coating failure
  • Additional clinical data may be required for novel surfaces or designs with limited clinical history

Non-clinical testing

  • Metallurgical analysis of materials (composition, trace elements, grain size, phases)
  • Microstructure analysis of modified surface (thickness, layers, pore characteristics)
  • Physical properties of untreated substrate surface
  • Mechanical testing including:
    • Shear fatigue strength (minimum 10^7 cycles)
    • Static shear strength (>20 MPa for porous coatings)
    • Static tensile strength (>20 MPa for porous coatings)
    • Abrasion resistance testing
    • Plastic deformation assessment

Biocompatibility

  • Testing required per ASTM F 748 and F 981
  • Animal implant studies needed for novel material combinations
  • Assessment of tissue response, including tissue apposition, ingrowth depth, and junction strength

Safety

  • Corrosion testing required for novel material combinations
  • Surface coating integrity assessment
  • Wear debris evaluation

Other considerations

  • ASTM C 633: Adhesion or Cohesive Strength of Flame-Sprayed Coatings
  • ASTM F 1044: Shear Testing of Porous Metal Coatings
  • ASTM F 1147: Tension Testing of Porous Metal Coatings
  • ASTM F 1160: Constant Stress Amplitude Fatigue Testing of Porous Metal-Coated Metallic Materials
  • ASTM F 748: Selecting Generic Biological Test Methods for Materials and Devices
  • ASTM F 981: Assessment of Compatibility of Biomaterials for Surgical Implants

Original guidance

  • Testing Requirements for Orthopedic Implants with Modified Metallic Bone-Interface Surfaces
  • HTML / PDF
  • Issue date: 1994-04-27
  • Last changed date: 2020-03-17
  • Status: FINAL
  • Official FDA topics: Medical Devices, Premarket
  • ReguVirta summary file ID: 52a9564a4c8b3ba43a7727325dd75533
This post is licensed under CC BY 4.0 by the author.