ASTM F1717 Corpectomy model

We offer various test methods for the mechanical characterization of spinal implants in a vertebrectomy model according to the test standard ASTM F1717. In a vertebrectomy model the bridging of a vertebral body without anterior support is to be simulated. The spinal implants are firmly connected to two test-blocks of UHMWPE with defined material properties, whereby a defined gap between the blocks simulates the absence of a vertebral body. The test-blocks are adapted in their shape and properties to different positions of the spine (e.g. lumbar or cervical). From the following range, we will select the appropriate test procedures for your individual spinal implants:

  • Static test methods
    1. Bending test under compression:

    The construct of test-blocks and the spinal implant is clamped into the test device and a pressure load (max. 25 mm/min) is applied. The force-displacement curve is recorded and evaluated with regard to the mechanical properties (including stiffness and strength) under pressure.

    2. Bending test under tension:

    The construct of test-blocks and the spinal implant is clamped into the test device and a tensile load (max. 25 mm/min) is applied. The force-displacement curve is recorded and evaluated with regard to the mechanical properties (including stiffness and strength) under tension.

    3. Axial Torsion:

    The construct of test-blocks and the spinal implant is clamped into the test device and a constant torsion (max. 60 °/min) is applied. The axial load should be near to zero. The torque- angle curve is recorded and evaluated with regard to the torsional mechanical properties (including stiffness and strength).

  • Dynamic test methods
    Following the static tests, the tests are performed dynamically with new test specimens over 5 million cycles. A constant ratio of the maximum to the minimum load of R = 10 should be guaranteed. The maximum load is initially selected freely. When the implants survive 5 million cycles, the force is varied. In the end, a difference between two loads, where the implant dynamically fails or survives, should be less than 10%. 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.