Endurance Testing of Hip Prosthesis Components

Servo-hydraulic testing machine especially for testing hip protheses
Hip prosthesis testing with a servo-hydraulic Zwick testing machine (PresseBox) (Ulm, ) An artificial hip replacement (total replacement arthroplasty) must perform its function in the body for many decades, and wear should be as small as possible so as to prolong the life of the prosthesis. Repairing a failed part can be more difficult than the original operation so quality and safety are paramount for the manufacturer, since faulty designs can lead to injuries in the patients and to substantial costs from product liability lawsuits.

In order to ensure the quality of hip prostheses, it is important to test the reliability of the individual components as well as the complete system in a test setup simulating the dynamic situation in the human body. One method for testing the complete hip prosthesis system is the dynamic fatigue test as described by ISO 7206-4 and ISO 7206-8.

Zwick has developed a servo-hydraulic testing machine especially for testing hip prostheses which allows the application-specific mounting of the acetabular cup and the cemented mounting of the hip prosthesis shaft in accordance with standards. In order to verify the lifetime of the shaft under standardized conditions, the testing machine simulates the dynamic loading of the hip prosthesis shaft during walking under already existing loosened conditions in the proximal bone bed.

The HC10 servo-hydraulic fatigue testing machine has a force rating up to 10kN and high load frame stiffness to ensure precision at high testing frequencies. The actuator can operate at frequencies up to 100 Hz.

For the correct cementing of the hip prostheses an embedding fixture was designed with angles as defined by ISO 7206-4. This ensures correct embedding and guarantees the reproducibility of the results. The modular design of the complete testing system allows other mounting fixtures for hip prostheses with different geometries and fixing methods to be easily integrated. A fluid chamber with temperature control unit can be provided upon request for in-vivo simulations.

Zwick’s software testXpert® II controls the test and the carries out the evaluation of the parameters required by the testing standard. A pre-configured test program is available for this test which simplifies the set-up and configuration and guarantees compliance with the Standards. In addition, testXpert® II can also provide enhanced traceability in accordance with FDA 21 CFR Part 11.

A flexible and modular range of tools is available for additional testing applications.

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Zwick GmbH & Co. KG
August-Nagel-Straße 11
D-89079 Ulm

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