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Design Validation for FDA Pre-Market Approval

003-1Exponent frequently conducts start- to-finish medical design validations for our clients. For example, a start-up manufacturer of novel stents needed design validation for FDA pre-market Approval (PMA). Exponent engineers and scientists used our in-house microfocus x-ray equipment to measure stent dimensions in vessels at various internal pressures. This allowed us to make a conservative estimation of deflections the stents would likely see in vivo.


003-2We conducted finite element analysis (FEA) to determine the expected stresses and strains given the in vivo deflections. Using in-house fatigue- testing fixtures, Exponent conducted deflection-life and 400-million cycle durability fatigue tests on stent specimens. FEA of the deflection- controlled testing allowed the determination of a margin with respect to expected in vivo conditions. Exponent also conducted corrosion testing of the stents per ASTM F 2129 specifications. Just prior to PMA submission, the client found that several stents fractured during expansion tests. Exponent was able to show that the stents fractured due to improper ultrasonic cleaning from a vendor.