ISO 7206 | Medical Devices and Equipment | Fatigue Testing
ISO 7206 is a testing standard designed to measure the endurance properties of stemmed femoral components of hip implants. This test procedure is applicable to implants that have a plane of symmetry, or have performed anteversion or double curvature of the stem, and to prostheses designed for use in revision surgery.
A dynamic testing machine and the ISO 7206 fixture are required to perform this test. The lower portion of the test specimen is first embedded in a solid medium. A cyclic load is applied to the head of the specimen, producing two-plane bending and torsion, until the specimen breaks or until the chosen number of cycles is attained.
Before conducting ISO 7206, it is important to read the entire specification in the relevant ISO publication.
ISO 7206 | Medical Devices and Equipment | Fatigue Testing
- Prepare the test specimen as described in the standard. Measure the distance between the center of the head of the implant to the most distal point of the stem (length CT in Figure 1). Define KL and KT lengths as shown in Figure
- Position the specimen in the holder as designated in the standard. Make sure the axis of KL of the stem is oriented at the calculated offset angles.
- Mount the holder and the specimen in the aligning device. Clamp the holder firmly in position and ensure that the correct orientation of the specimen is maintained. Measure the head offset length.
- Embed the specimen in the embedding medium in the holder until the medium has hardened sufficiently to support the specimen unaided.
- Start the test at a frequency specified in the standard.
- Measure and record the horizontal and the vertical component of the dynamic deflection of the head (f).
- Stop the test until one of the following occurs:
- Deflection exceeds 1.25 x f
- Deflection exceeds 5mm (0.2in)
- Specimen breaks
- The chosen number of load cycles is attained
- Record the number of cycles, the minimum and maximum loads.
Calculations:
- Maximum Load
- Minimum Load
- Number of Cycles
ISO 7206 | Medical Devices and Equipment | Fatigue Testing
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