Procedures for the mechanical testing of trauma and osteosynthesis implants
We offer a testing procedure in accordance with ASTM F382 for comparing bone plates with respect to their mechanical properties. Specifically, the following two tests can be performed
- Static four-point bending test
The bone plate is positioned in the test fixture and loaded until a significant drop in force occurs (fracture or material yielding). During the test, a force–displacement diagram is recorded and evaluated with respect to bending stiffness and bending strength. - Dynamic four-point bending test
The bone plate is clamped in the test fixture and subjected to loading over a defined number of cycles. The applied load should correspond to 75, 50, or 25% of the bending strength and be applied at a frequency of 1–10 Hz. Subsequently, an M–N diagram (maximum bending moment versus number of cycles) is generated and the fatigue strength is determined.
In addition to the mechanical characterization of bone plates, we are also pleased to advise you on correct labeling, packaging, and the content of the manufacturer information to be provided with the product.
We offer characterization of angled plates in accordance with ASTM F384. Specifically, we can perform static and dynamic bending tests:
- Static bending test
The angled plate is fixed to a rigidly clamped test block via the side plate, while the angled portion of the implant remains free. A constant displacement acting parallel to the side plate is applied to the angled portion of the implant (rate: 10 mm/min). Bending stiffness and bending strength are determined from the force–displacement curve. - Dynamic bending test
The angled plate is aligned in the same manner as in the static bending test and loaded over a defined number of cycles. The applied load should correspond to 75, 50, or 25% of the bending strength and be applied at a frequency of 1–10 Hz. Subsequently, an M–N diagram (maximum bending moment versus number of cycles) is generated and the fatigue strength is determined.
In addition to the mechanical characterization of angled plates, we are also pleased to advise you on correct labeling, packaging, and the content of the manufacturer information to be provided with the product.
We offer various test methods for the mechanical characterization and classification of bone screws in accordance with ASTM F543. Together with you, we select the appropriate test procedures from the following range to suit your specific screw design:
- Test method for determining torsional properties
The bone screw is clamped in a fixture and loaded at a constant rotational speed (1–5 rpm) while a torque–rotation angle curve is recorded. This curve is then evaluated with respect to yield point, maximum torsional moment, and fracture angle, enabling a qualitative comparison of different screws. - Test method for determining insertion and removal torque
The screw is inserted into a standardized test block under a constant axial load and at a constant rotational speed (1–5 rpm), and subsequently removed, in order to determine material-independent comparative values for insertion and removal torque. - Test method for determining axial pull-out strength
The screw is inserted into a standardized test block at a constant rotational speed (3 rpm) up to a defined insertion depth and subsequently pulled out axially at a constant speed (5 mm/min) until the screw loosens or fails. - Test method for determining the cutting performance of self-tapping bone screws
To determine the axial force at which the self-tapping action of the screw begins, the screw is inserted into a pre-drilled test block at increasing axial force (1–3 N/s) and a rotational speed of 30 rpm. - Classification of metallic bone screws
Based on various geometric characteristics, screws are classified into categories HA, HB, HC, and HD. - Classification of the connection between screw head and bit
Based on various geometric characteristics, the connections between screw head and bit (drive connection) are specified.
In addition to the mechanical characterization and classification of bone screws, we are also pleased to advise you on correct labeling, packaging, and the content of the manufacturer information to be provided with the product.
We offer various test methods for the mechanical characterization of bone staples in accordance with ASTM F564. Together with you, we select the appropriate test procedures for your bone staples from the following range:
- Static bending test
A bone staple is clamped in the test fixture and loaded in a four-point bending test at a constant speed of 25.4 mm/min. A force–displacement curve is recorded, and bending stiffness and bending strength are determined. - Dynamic bending test
Two different dynamic bending tests are offered: a four-point bending test and a combined tensile or compressive and bending load test. In both cases, the bone staples are firmly clamped in the test fixture and cyclically loaded (50% or 75% of the static bending strength). The test ends when the bone staples fracture or when a defined number of cycles has been reached. The test is performed in liquid at 37 °C. - Pull-out test (staple/bone)
A bone staple is inserted into bone (or an analogous test material) and subsequently removed at a constant speed. A force–displacement curve is recorded, in which a significant drop in force indicates the pull-out force. Upon request, this test can also be performed in liquid to better simulate physiological conditions. - Holding strength in soft tissue
A bone staple (or multiple staples) is used to create a connection between soft tissue and bone (physiological or analogous materials). Subsequently, a tensile load is applied to the soft tissue at a constant speed, perpendicular to the bone staple, while a force–displacement curve is recorded. The test ends when the bone staple is released or one of the materials fails. Upon request, this test can also be performed in liquid to better simulate physiological conditions.
We offer characterization of the design and mechanical performance of intramedullary nails in accordance with ASTM F1264.
- Static four-point bending test
An intramedullary nail is clamped in the test fixture and loaded until a significant drop in force occurs (fracture or material yielding). During the test, a force–displacement curve is recorded and evaluated with respect to bending stiffness and bending strength. - Dynamic four-point bending test
An intramedullary nail is clamped in the test fixture and loaded over a defined number of cycles. The applied load should correspond to 75, 50, or 25% of the bending strength and be applied at a frequency of 1–10 Hz. Subsequently, an M–N diagram (maximum bending moment versus number of cycles) is generated and the fatigue strength is determined. - Static torsion test
An intramedullary nail is clamped in the testing machine and a constant axial force (5–10 N) is applied. Subsequently, torsion of 5° is applied at a constant rate of 5°/min. A torque–rotation angle curve is recorded, whose linear slope corresponds to torsional stiffness. - Dynamic four- or three-point bending test of locking screws
The dynamic bending test of the locking screw is performed in accordance with the test procedure used for intramedullary nails.
In addition to the mechanical characterization of intramedullary nails, we are also pleased to advise you on correct labeling, packaging, and the content of the manufacturer information to be provided with the product.
For fatigue testing of composite sliding nails, INNOPROOF GmbH has established the in-house procedure IP-05-05. The spatial alignment of the sliding nail is based on the testing standard for hip endoprostheses, ISO 7206-4. The load conditions for fatigue testing are defined in consultation with the customer. Typically, tests are performed over 100,000 to 1,000,000 load cycles.
If you have questions regarding physiological loads and expected application durations until complete fracture healing, we are happy to provide consultation.
