ASTM F2077 Intervertebral fusion devices*
We offer various test methods for the mechanical characterization of fusion implants for the spine according to the test standard ASTM F2077. From the following range, we will select the appropriate test procedures for your individual fusion implants:
- Static test methods
1. Compression Test:
The fusion implant is placed between two test-blocks made of steel and clamped into the test device. The surfaces of the blocks are adapted to the implant design. The construct is loaded with a constant displacement (max. 25 mm/min) and the force-dispacement curve is recorded and evaluated with regard to the mechanical properties (including stiffness and strength) under pressure.
2. Shear Test:
This test is performed according to the compression test, except that the bottom block has a 27° or 45° inclined base. As a result compressive and shear loads are applied to the implant at the same time.
3. Axial Torsion:
As in the compression or shear test, the fusion implant is clamped between two blocks. Depending on the later implantation site of the spine, the implant is loaded with an axial preload of 100 N (cervical), 300 N (thoracic) or 500 N (lumbal). Under a constant axial load, a rotation at a constant speed (60 °/min) is applied and a torque-angle curve is recorded. This is evaluated with regard to the mechanical properties (including stiffness and strength) under torsion.
- Dynamic test methods
Following the static tests, the tests are performed dynamically with new test specimens over 5 million cycles, with the test-blocks made of polyacetal. A constant ratio of the maximum to the minimum load of R = 10 for the dynamic compression and shear tests and R = 1 for the dynamic torsion tests should be ensured. The maximum load should be 25, 50 or 75% of the respective maximum load. In the end, a difference between two loads, where the implant dynamically fails or survives, should be less than 10%. The test is completed when the 5 million load cycles are reached or a mechanical failure of the implants occurs. The tests should be carried out under laboratory conditions (air and room temperature), but can also be repeated in Ringer solution at 37 °C, if necessary, in order to simulate the physiological ambient conditions and to consider possible corrosive effects
*We offer this testing service as part of our accredited scope.