ASTM F543 Annex 3 Axial Pullout Strength Metallic Bone Screws

  

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Bone screws are designed to be inserted into bone or bone-like material to stabilize the area. The screws are subjected to different loads as the body moves and as the bones heal. This standard specification is used to determine how much force is required to cause a failure, either a break or removal, from the bone material. This method is used to compare uniformity of different screws.

The testing apparatus is described in detail in the full specification

Inserting the screw in to the test block is critical. It must not exceed 20mm depth  or 60% of length if smaller than 20mm screws, inserted at a rate of 3r/min.

The next part of the test is the axial pullout. Apply tensile force at a rate of 5mm/min until the screw pulls out of block or fails.

By reviewing the load vs. displacement curve with the max load highlighted, a determination is made to define the screw failure. (shaft, threads, or material)

Using a Biaxial Testing System like the ADMET eXpert 2600 series, will allow you to apply torsional, tensile, and compressive loads to your specimens. The specific fixtures required according to ASTM F543-A3 are provided by the customer or by ADMET. Additional grips, fixtures, baths, chambers, and load cells available at www.ADMET.com Although the video below is not the axial pullout test, it shows the biaxial capability of the dual column system.