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Avoiding Pitfalls: Testing Considerations. How Do I Test It?. Which tests? Which specifications? ASTM, ISO, Custom Protocols What size? How many? What targets? Minimum Acceptance Criteria? What predicate devices?. How do I test it? Guidance Documents. FDA Guidance Documents:
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How Do I Test It? • Which tests? • Which specifications? • ASTM, ISO, Custom Protocols • What size? • How many? • What targets? Minimum Acceptance Criteria? • What predicate devices?
How do I test it? Guidance Documents • FDA Guidance Documents: • Guidance for Industry and FDA Staff: Spinal System 510(k)s • Guidance for Industry and FDA Staff - Class II Special Controls Guidance Document: Intervertebral Body Fusion Device • Information about Indications, Mechanical Testing, Wear Testing, Animal and Clinical studies, Sterilization, Worst Case Scenarios, etc.
ASTM Specifications • Test methods intended to provide a basis for the mechanical comparison among past, present, and future implant assemblies. • Scope • Reference Documents • Terminology • Summary of Test Method • Significance and Use • Apparatus • Sampling • Procedure (Starting place for protocol development) • Report • Precision and Bias (Repeatability)
Know your target - Predicate Device & Worst Case Evaluation • Know what predicate values you are targeting ahead of time • Perform testing (feasibility if necessary) • Identify and Evaluate Worst Case Scenario • Finite Element Analysis (FEA) – Allows for quick evaluation of stresses in various loading conditions
Static Testing • How much force will it take to break it? • Ultimate force • Yield force • Stiffness • Failure Mode • Differentiates between elastic and plastic deformation regions • Determines starting points for fatigue curve
Dynamic Testing (Fatigue) • What is the highest load that will survive a particular cycle count? • Load versus cycle count endurance curve
Testing - Common Spine Specifications • Pedicle screw, rod, and hook systems • ASTM F1798 • ASTM F1717 • ASTM F2706 • ASTM F2193 • Spacers and cages • ASTM F2077 • ASTM F2267 • Screws • ASTM F543
ASTM F1798 • Spinal Implant Connection Testing • Flexion/Extension • Axial Slip • Torsional Grip • Transverse Moment
ASTM F1717 • Spinal Implant Constructs in Vertebrectomy Model • Static Compression • Dynamic Compression • Static Tension • Static Torsion
ASTM F1717 Failure Modes • Common Failures • Screws • Rods • Laser Markings • Laser markings create stress risers • Alpha Case
ASTM F2077 • Intervertebral Body Fusion Devices • Static & Dynamic Compression • Static & Dynamic Compression Shear • Static & Dynamic Torsion • Subsidence (ASTM F2267) • Expulsion
ASTM F2077- Failure Modes Static Failure Mode – Plastic Deformation Dynamic Failure Mode - Fatigue Cracks
Wear Testing • Articulating Surfaces, Mixed Material Devices • In vitro Testing – Wear • Mass Loss Analysis • SEM particulate evaluation • Multi-Axis Wear Testing • ISO 18192-1:2011 • Mass Loss Analysis • SEM particulate evaluation
Resources Available • Pre-510(k) meeting with the FDA • Draft Guidance for Industry and FDA Staff Medical Devices: The Pre-Submission Program and Meetings with FDA Staff • Regulatory and Consulting Agencies • Highly recommended if performing submissions for the first time • Help determine worst case scenario, testing needs, and put together 510(k) submissions • Consult your testing laboratory • Familiar with Specifications (Participate in ASTM) • Test similar devices, see newest technologies and methods • Provide recommendations based on experience • Develop fixturing and protocols