ASTM F2077 | Intervertebral Body Fusion Devices | Mechanical Properties
ASTM F2077 is a testing standard that covers both static and fatigue test methods to determine the mechanical properties of intervertebral body fusion device assemblies specific to the lumbar thoracic, and cervical spine. During static testing a motion segment should be simulated via a gap between two stainless steel blocks. For fatigue testing, the motion segment should be simulated via a gap between two polyacetal test blocks.
This test method quantifies the static and dynamic characteristics of different designs of intervertebral body fusion device assemblies and evaluates their mechanical performances. Tests are conducted in vitro and the loads applied may differ from the complex loading see in vivo, therefore, results may not directly predict in vivo performance. Nevertheless, they can be used to compare mechanical performances. The location within the simulated vertebral bodies and position of the intervertebral body fusion device assembly with respect to the loading axis will be dependent upon the design, the manufacturer’s recommendation, or the surgeon’s preferred method for implant placement.
The test utilizes a static and dynamic torsion test system and ASTM F2077 torsion fixtures. ADMET’s eXpert 9900 Torsion Test System is capable of performing high capacity torsion testing both statically as well as dynamically. Before conducting ASTM F2077, it is important to read the entire specification in the relevant ASTM publication.
ASTM F2077 | Intervertebral Body Fusion Devices | Mechanical Properties
Prepare samples as described in the standard. Make sure each part is unused and labeled properly.
Static testing:
- Insert the intervertebral body fusion device assembly between two prepared metal blocks.
- Apply the load as described; in position control at a rate specified in the testing standard until failure.
- Record the load displacement curve.
Calculations:
- Yield Displacement
- Stiffness
- Yield Load or Moment
- Ultimate Displacement
- Ultimate Load or Moment
Dynamic/fatigue testing:
- Insert the intervertebral body fusion device assembly between two prepared polyacetal blocks.
- Select and apply a load that is necessary to develop a well-defined load-cycle failure trend compromised of a minimum of six data points. Suggested maximum loads are 25, 50 and 75% of the ultimate static load. Stop the test at functional failure or when 5,000,000 cycles have been attained.
- Record load versus number of cycles to failure, all initial and secondary failures, modes of failure, and deformations of components.
Calculations:
- Maximum runout load (the highest load level for the specimen enduring 5,000,000 cycles)
ASTM F2077 | Intervertebral Body Fusion Devices | Mechanical Properties
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