ISO 7206-6 – Implants for surgery — Partial and total hip joint prostheses Part 6: Determination of endurance properties of head and neck region of stemmed femoral components
The test method described in this part of ISO 7206 is intended for the verification of the endurance properties of the neck region of stemmed femoral components of hip joint prostheses. This method is based extensively on that given in ISO 7206-4, which verifies the endurance properties of the complete femoral component under loading conditions that include a torsional component. The test conditions in ISO 7206-4, especially the height of the specimen embedding, are intended to represent the clinical situation where the prosthesis has become loosened in the femur, whereas the test conditions in this part of ISO 7206 are intended to represent a correctly and firmly fixed prosthesis. Therefore, it should be noted that the tests in this part of ISO 7206 may not be representative of the most unfavorable clinical conditions.
This part of ISO 7206 specifies test methods and the fatigue performance for the endurance properties, under specified laboratory conditions, of neck region of stemmed femoral components of total hip joint prostheses and stemmed femoral components used alone in partial hip joint replacement. This part of ISO 7206 does not cover the investigation of the performance of the head or the neck-head junction. It is applicable to modular and non-modular designs made of metallic or non-metallic materials. It also specifies the test conditions so that the important parameters that affect the hip femoral components are taken into account and describes how the specimen is set up for testing.
The test specimen is embedded in a solid medium. For modular stems, the protruding part of the test specimen is immersed in a fluid test medium. A cyclic load is applied to the head of the test specimen until one of the conditions occurs.
- The vertical deflection exceeds a value of 3 mm greater than the deflection occurring in the first minute of running at test load.
- Fracture of the specimen.
- Completion of the prescribed number of load cycles.
- Inability of the testing machine to maintain the required load values.