ASTM F2582-20 Standard Test Method for Dynamic Impact between Femoral and Acetabular Hip Components

The standard “ASTM F2582-20 Standard test method for dynamic impingement between femoral and acetabular hip components” developed by the American Society for Testing and Materials (ASTM) describes a procedure for simulating dynamic impingement between the femoral and acetabular components in a hip prosthesis. This standard includes subsequent qualitative assessment of failure modes and, if necessary, quantitative assessment of changes in modular component connection strength.

This test method can be used to evaluate impingement between femoral components and: one-piece, modular, semi-constrained, bipolar, constrained, or dual-action acetabular components manufactured from polymeric, metallic, or ceramic materials.

Femoral and acetabular components are evaluated for fatigue fracture, deformation, delamination, wear, and fracture (ceramic components) under dynamic impact conditions. Modular acetabular prosthesis designs should be evaluated for additional failure mechanisms affecting any component or locking mechanism. Examples of failure modes for modular acetabular prosthesis designs include separation and loosening of any component or locking mechanism, or both.

The test method described can be used to evaluate dynamic properties. Various joint reaction forces and impacts can be applied to simulate known clinical conditions.

This test method should be used to evaluate and compare different femoral and acetabular prosthesis designs to assess damage tolerance under controlled laboratory conditions. Although the methodology described attempts to determine physiologically relevant movements and loading conditions, interpretation of the results is limited to in vitro comparisons between different femoral and acetabular prosthesis designs for their ability to resist impact damage modes under the specified test conditions.

The impact device must essentially have the following characteristics:

• An axis must be capable of applying a constant compressive load force for static loading.
• It must be capable of controlling and monitoring the angular displacement of three axes of motion.
• Equipment, “ASTM E4-13 Standard practices for strength verification of testing machines” requirements The loads used to determine the joint strength shall be within the range of the testing machine as defined in this standard.
• The compressive load shall be applied by means of a fixation that allows the acetabular prosthesis to be separated from the femoral prosthesis during the impact test. For the test principle, see the figure given in the standard. The acetabular prosthesis is allowed to move freely in the horizontal plane but is restricted from rotating about the load axis. For hip simulators that do not meet these requirements, deviations from the standard test setup must be justified. Dual mobility components may be fixed by means of a rotation stop to allow the moving component to be impact tested.

All acetabular and femoral components must represent implant quality products. This must include all sterilization processes where sterilization may affect the results.

Worst case examples should be determined and justified for all conditionally acceptable failure modes. Worst case examples) may vary by failure mode.

All components in the test must be considered, including head offset, stem geometry, surface finish and material, and acetabular components geometry, surface finish and material. Deformation and wear of components may occur during testing and, if so, will change continuously with the potential for change being emphasized when the component is repositioned. When unknown geometries are considered, the calculation of contact stresses and other stresses in the components required for the worst case analysis, for example, the stress in the locking mechanism region, must take into account the manufactured, undeformed geometry of the components.

When considering the overall worst case for each failure mode, consideration should be given to how deformation and wear will contribute to the overall worst case.

A possible technique is to model the neck-rim contact using the finite element method to determine the maximum stress configuration to support the worst-case analysis. Worst-case considerations may include contact geometry, material finish, thinnest acetabular components, components with the lowest initial locking strength, components exhibiting direct metal-to-metal contact, and component materials with the lowest strength.

A minimum of three specimens are used in the tests. Polymeric specimens should be preconditioned according to ASTM F2003-02 artificial aging standard.

Among the numerous testing, measurement, analysis and evaluation studies that our organization has provided for businesses in various sectors, our organization also provides testing services defined in the “ASTM F2582-20 Standard test method for dynamic impact between femoral and acetabular hip components” standard with its trained and expert staff and advanced technological equipment.