The standard “PI-73 Fatigue testing of total knee femoral components under closure conditions” developed by PI Medical Implants describes a fatigue test method to determine the fatigue behavior of knee femoral components under closure conditions. This test method simulates a clinically severe condition in which all bony support is lost and a single condyle supports the entire load at 90 degrees of tibiofemoral flexion.
This method provides guidance on how to test the total knee femoral component in closure fatigue. Total knee femoral components are tested to simulate single condyle loading at 90 degrees of tibiofemoral flexion. The highest load at which a group of specimens completes a predefined deflection without failure is the maximum deflection load.
Clinical fractures of total knee femoral components have been observed and reported in the literature. This test method provides a procedure to perform fatigue testing on total knee femoral components under closing conditions caused by an unsupported condyle, resulting in tensile stress on the articular surface and compressive stress on the inner, curved surfaces.
This test method aims to evaluate the fatigue performance of knee femoral components under a simulated joint loading condition. The load moves the posterior femoral condyle towards the anterior flange.
This test method simulates a clinically serious condition in which all bony support is lost and one condyle supports the entire load on the knee joint at 90 degrees of tibiofemoral flexion. Testing by this test method typically produces regions of high tensile stress at the intercondylar notch and at the articular surface where the anterior flange meets the condyle.
Loading of total knee femoral components using this test method may differ from actual in vivo loading conditions. The results obtained here cannot be used to directly predict in vivo performance. However, this test method is designed to allow comparisons between the fatigue performance of different total knee femoral component designs when tested under similar closure conditions.
Test specimens must conform to final design specifications. Certain processes in the manufacturing flowsheet may be omitted if they have been demonstrated not to affect the fatigue properties of the materials or devices. Design specifications include: material and post-manufacturing treatment, dimensions and tolerances, surface roughness, surface properties including surface features and coatings, and sterilization method.
In this regard, the standard “ASTM F3210-22 Standard test method for fatigue testing of total knee femoral components under closure conditions” developed by the American Society for Testing and Materials (ASTM) also provides guidance. This standard applies to metallic total knee femoral components used in total knee arthroplasty. Femoral components made of non-metallic materials, such as ceramics or polymers, can probably be evaluated using this test method. However, such materials may contain new failure mechanisms that are not considered in this test method.
The procedure described in ASTM F3210-22 is performed on total knee femoral components to support the determination of fatigue behavior under occlusal loading conditions. Occlusal loading refers to forces that act to decrease the femoral intercondylar depth, resulting in tensile stress at the articular surface of the femoral condyle. Different designs may be characterized as, but are not limited to, posterior cruciate ligament retention, posterior stabilization, and revision. This standard does not address the evaluation of femoral components under occlusal loading conditions that also lead to clinical failure. Under occlusal loading conditions, forces are applied to the internal contour of the femoral component in a manner that increases the intercondylar depth or opens the femoral component.
Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the “PI-73 Fatigue testing of total knee femoral components under closure conditions” standard with its trained and expert staff and advanced technological equipment.
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