The analysis of retrieved implants is essential for a complete understanding of how a device functions, as it provides unique information related to in vivo device mechanics, kinematics, and material performance. For this reason, recent 522 Orders by the FDA for posterior dynamic stabilization spinal devices and metal-on-metal hip replacements have required retrieval analysis plans as an integral component of post-market surveillance.
Exponent has extensive expertise in creating and managing international multicenter programs to collect and analyze components from explanted orthopedic, spine, and cardiovascular implants including total joint replacements, artificial discs, pacemakers, implantable cardioverter-defibrillators (ICDs) and stents. Procedures may include wear and deformation analysis via optical imaging techniques (Figures 1 and 2), evaluation of fracture surfaces, and evaluation of material degradation. Exponent is accredited to ISO 17025 (A2LA Certificate 2561.01) for it retrieval protocols based on ASTM F561, “Standard Practice for Retrieval and Analysis of Medical Devices and Associated Tissues and Fluids” Custom analyses can also be completed based on specific designs. Where necessary, Exponent’s biomedical engineering consultants can also be present at meetings with regulatory bodies in order to present the results of the analyses conducted. Our core capabilities consist of the following:
Capabilities
- Familiarity in working with international centers for explant collection
- Evaluation of wear patterns, failure mechanisms, fracture, corrosion, degradation, and deformation (e.g., Figure 1)
- Correlation of retrieved damage modes and mechanisms to in vitro tested devices (e.g., Figure 2)
- Evaluation of retrievals comprised of traditional (UHMWPE on CoCr) bearing materials, alternate (metal and ceramic) bearing materials and novel new bearings (hard coatings, hydrogels, alternate polymers)
- MicroCT and microscopy capabilities (e.g., Figure 3)
- Device-specific kits and forms that can be shipped in compliance with all IATA shipping regulations (e.g., Figure 4)
- Evaluation of fluid and tissue surrounding the implant, including histology, trace metal, and particle analysis
- Chemical and electrical evaluation of batteries in pacemakers and implantable cardioverter-defibrillators and associated leads (e.g., Figure 5)
- Reports suitable for direct submission to the FDA containing methodology and results of all findings
- Experience with responding the FDA deficiency letters.
Figures
Figure 1. SEM image of retrieved elbow joint replacement.
Figure 2. Images of a retrieved metal-on-metal (MOM) cervical total
disc replacement (left, 2.3 y) and an in vitro tested MOM cervical disc
replacement (right, 0.1 MC).
Figure 3. Optical microscopy and microCT analysis of retrieved
polymer component from a posterior dynamic stabilization device.
Figure 4. Components that may be included in a device-specific
retrieval kit.
Figure 5. Retrieved pacemaker.