ASTM F2502 – Standard Specification and Test Methods for Absorbable Plates and Screws for Internal Fixation Implants

This specification and test methods cover the mechanical characterization of plates and screws for orthopedic internal fixation.  Covered devices are fabricated from one or more hydrolytically degradable polymer (from this point on referred to as “absorbable”) resins or resin composites.

Absorbable devices are intended to degrade and absorb over time once they are implanted into the body.  This makes a removal operation unnecessary, which is especially advantageous for pediatric patients.  While the polymer degrades due to hydrolytic reaction with the environment, the mechanical performance of the device also deteriorates.  The key to developing mechanically effective fracture fixation systems based on absorbable devices is to provide an adequate level of fixation strength and stiffness for a time frame that exceeds that expected for fracture healing.  Once the fracture is healed, the device can be completely absorbed by the body. The biological performance of the device, particularly for application at a bony site, may be enhanced by incorporation of bioactive fillers in the polymer.  Absorbable devices will be tested using test methods that are similar to those used to evaluate conventional metallic devices.  The pre-test conditioning requirements, handling requirements, and time-dependent mechanical property evaluations for absorbable devices shall be considered.

The following annexes are included:

  • Annex A1—Test Method for Determining the Torsional Properties of Absorbable Bone Screws.
  • Annex A2—Test Method for Driving Torque of Absorbable Bone Screws.
  • Annex A3—Test Method for Determining the Axial Pullout Strength of Absorbable Bone Screws.
  • Annex A4—Test Method for Single Cycle Bend Testing of Absorbable Bone Screws.

Test results are shown below for each test method Annex.

ASTM F2502 Graph 1

ASTM F2502 Graph 2

ASTM F2502 Graph 3

ASTM F2502 Graph 4

Photos of Test