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Hip Implant ASTM Mechanical Strength Testing of Femoral Prostheses

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Hip Implant ASTM Mechanical Strength Testing of Femoral Prostheses

ASTM and ISO have standard test methods for mechanical testing the four separate parts that make up a hip prostheses; the femoral head, femoral stem, acetabular shell, and acetabular linear. ASTM has standardized test methods for determining mechanical properties of hip implants to ensure high quality and safety for users.

This article lists all the ASTM and ISO standards involved in mechanical testing the four parts of a hip implant including fatigue, tensile, peel and shear. Artificial hip implants are currently tested to ensure in vivo performance for 10 years. In vivo loading is difficult to quantify because the human body is capable of a wide range of motion, which also varies from person to person. To ensure that orthopedic hip implants are capable of the loading condition of any patient ASTM and ISO have created a number of mechanical testing. ASTM F2068 is a compilation of all the ASTM testing requirements for hip implants, including mechanical testing, material requirements, surface finishes and more.

ASTM F2068 lists four mechanical properties of orthopedic hip implants that must be tested prior to use in humans. To verify long-term strength of hip prostheses designs simple static testing is required to evaluate the compressive, tensile and torsional loading required to fracture a hip implant. Fatigue life tests of artificial hip implants are critical because fatigue failure is more common than catastrophic failure, and it most closely matches in vivo forces. Loading hip implant test samples with load-controlled sinusoidal waveforms are most common, and mechanical fatigue tests last in excess of ten million cycles. Metal spray is often used to coat hip prostheses, however, problems can arise if the spray chips off and goes into the bloodstream. Testing the abrasion resistance with peel tests is an effective method to ensure safe high-quality thermal spray adhesion on the orthopedic hip implant. Shear testing is also done to test the adhesion of calcium phosphate and other metal coatings used on orthopedic hip implants.