ISO 16402 Implants for Surgery - Acrylic Resin Cement - Flexural Fatigue Testing of Acrylic Resin Cements for Orthopaedic Use

For the implementation of the standard “ISO 16402 Implants for surgery - Acrylic resin cement - Bending fatigue testing of acrylic resin cements used in orthopedics” developed by the International Organization for Standardization (ISO), it is indispensable for the implementation of the following standards:

• ISO 5833 Implants for surgery - Acrylic resin cements
• ISO 16428 Implants for surgery – Test solutions and environmental conditions for static and dynamic wear tests on implantable materials and medical devices

The tests utilize rectangular bar-shaped test specimens. The method for preparing these specimens is described in the standard.

The flexural strength of the obtained test specimens is determined by means of a four-point flexural test under quasi-static and cyclic loading conditions. Two test methods are described under cyclic loading conditions. The first follows the Wöhler method (S/N curve method) and determines the behavior over the entire range of stress levels. The second (low stress method) determines the behavior only at low stress levels. These low stress levels specified are considered to correspond to the stress levels expected to be encountered in clinical use.

Equipment used in the tests includes:

• Cement mixing equipment as recommended by the cement manufacturer.
• Moulds made of a suitable material for producing rectangular bar specimens of dimensions 75 mm long, 10 mm wide and 3,3 mm deep directly into their final shape. If preferred, one or more moulds may be used to produce 3,3 mm thick plates and the specimens may then be cut to size using a saw. All surfaces of moulds in contact with cement should be finely finished with 400 grade sandpaper. Materials of sufficient hardness such as aluminium alloys or stainless steel are suitable.
• Flat, smooth sheets of a suitable material and size to cover the top and bottom surfaces of the moulds (two for each mould).
• Mould release agent to facilitate separation of samples from moulds. Teflon spray, vacuum grease or wax are suitable.
• Polyester film to cover the plates of the mold.
• C clamps or other devices to clamp the mold or molds between the top and bottom plates.
• Bending testing machine equipped with a load measuring, controlling and recording device with plus/minus 200N sensitivity, capable of applying loads up to 5 N, optionally increasing linearly or rotating sinusoidally within the selected value range at a frequency of 2 Hz.
• Four-point bending test fixture having the dimensions shown in the figure given in the standard, with means to prevent initial misalignment, changes in alignment and walking of the test specimen on supports during the test. The loading points shall be of the rolling type and shall be 3 mm in diameter. The test fixture shall be such that equal loads are applied to all loading points.
• Water bath to maintain the test specimen and loading apparatus at a temperature of 37 degrees plus/minus 2 degrees.
• Saw.
• 400 grade sandpaper.

When preparing test samples, the mold or molds, plates, mixing equipment and cement to be used (both powder and liquid components) should be kept at a temperature of 2 degrees plus/minus 23 degrees for at least 2 hours before pouring the test samples. The samples should be poured at a temperature of 23 degrees plus/minus 2 degrees.

Among the numerous testing, measurement, analysis and evaluation studies that our organization has provided for businesses in various sectors, it also provides testing services defined in the “ISO 16402 Implants for surgery - Acrylic resin cement - Bending fatigue testing of acrylic resin cements used in orthopedics” standard with its trained and expert staff and advanced technological equipment.