Biotribology

Understanding the tribological performance of medical devices and the materials used in their design is a critical part of the design process. Exponent’s pin-on-disc testing can be used for screening candidate biomaterial couples and for optimizing design performance. Our expertise in conducting and managing wear testing of orthopedic, spine and cardiovascular devices, includes not only the gravimetric and volumetric analyses, but also particle analysis and advanced metrology. Exponent’s reports are prepared for submission directly to regulatory bodies worldwide.

Exponent is accredited to ISO 17025 (A2LA Certificate 2561.01) for its wear testing protocols and analysis based on:


  • ASTM F2423 - Standard Guide for Functional, Kinematic, and Wear Assessment of Total Disc Prostheses
  • ISO 18192-1 - Implants for Surgery -- Wear of Total Intervertebral Spinal Disc Prostheses -- Part 1: Loading and displacement parameters for wear testing and corresponding environmental conditions for test
  • ASTM F732 - Standard Test Method for Wear Testing of Polymeric Materials Used in Total Joint Prostheses
  • ASTM F1877 - Standard Practice for Characterization of Particles

Exponent also has experience in managing in vitro testing protocols conducted per:


  • ISO 14242 - Implants for surgery -- Wear of total hip-joint prostheses
  • ISO 14243 - Implants for surgery -- Wear of total knee-joint prostheses
  • ISO 25539 - Cardiovascular implants - Endovascular devices - Part 2: Vascular stents
  • ASTM F2624 - Standard Test Method for Static, Dynamic, and Wear Assessment of Extra-Discal Spinal Motion Preserving Implants
  • ASTM F2477 Standard Test Methods for in vitro Pulsatile Durability Testing of Vascular Stents

Exponent has extensive expertise in establishing wear test programs that contain the critical analyses necessary to assist in answering questions for regulatory submission. These include conducting the basic gravimetric analysis on parts, as well as dimensional analyses, optical microscopy, scanning electron microscopy, surface roughness analysis, chemical analysis, particle analysis, microCT and custom analyses where appropriate. The results of the wear protocols can be synthesized into reports suitable for direct submission to the regulatory bodies and contain methodology and results of all findings.

Figure 1. MTS Spine Wear Simulator used to conduct wear testing on total discreplacements, nucleus pulposus replacement devices, dynamic stabilization devices and cadaveric tissue implanted with devices.

Figure 2. AMTI six-station pin-on-disc wear simulator used to assess medical device bearing material couples.

Figure 3. UHMWPE particles obtained from in vitro wear testing of a TDR using ASTM F1877 as a guide.

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