This benchtop test provides empirical evidence for the mechanical properties of intramedullary fixation devices such as bone screws. The example test described here is 3-point static bending testing of bone screws.
Testing objective is determining the stiffness of bone screws per ASTM F1264-16. Bending tests are performed at ambient air environment in displacement control. Bending fixture stiffness is measured, and its artifact is taken into account in bone screw stiffness calculations as shown here: 1/(Screw-Fixture Stiffness)=1/((Screw Stiffness)+1/(Fixture Stiffness). A device failure is defined by the device manufacturer (for example, any visibly cracked or broken lead, or a change in conductivity / DC resistance). The device manufacturer will also examine the devices post-testing against the acceptance and/or failure criteria.
The test system utilizes a 3-point bending fixture designed by MDT (see picture) that is integrated with a Bose ElectroForce 3200 Series Test Instrument. The ElectroForce 3230 instrument used is rated to 450N (100 lbs) and performs precision materials tests including tension/compression, fatigue and dynamic materials characterization.
MDT tests are conducted in accordance with ANSI/ISO/IEC 17025-2005. Testing schedules and resource needs are determined during project kickoff meetings with MDT engineers and the customer. Services are performed in accordance with standard operating procedures and test protocols specific to the project. Standard tests do not begin without a protocol signed by both the customer and an MDT representative. For feasibility or non-standard tests, MDT will develop a method and protocol with customer input and will review the final process with the customer prior to initiation of the test.
The test equipment software monitors the cycle count and displacement throughout the duration of the test. MDT engineers monitor the test daily and record the temperature and pressure for the system, as well as the outside radial strain at predetermined positions for each device being tested. MDT sends weekly updates to ensure customers are apprised of the status of their test. Updates include raw data collected throughout the week for the customer's analysis.
Inspection Services Offered:
MDT offers several inspection and monitoring methods including:
• High speed video inspection of devices or fixture validation
• Visual Inspections
Tests are conducted in accordance with ANSI/ISO/IEC 17025-2005. In compliance with this standard, MDT test reports include comprehensive documentation and summary of the test protocol and results. Any test method deviations, additions, or exclusions are documented and reviewed with the customer prior to beginning the test. Information within the report includes the specific test conditions, statements of compliance with test protocol, and the estimated measurement uncertainty. The reported results only relate to the items tested. Any opinions and interpretations provided by MDT are clearly marked as such. Any additional information required by customer-specific methods will also be noted. At the conclusion of the test, MDT provides the customer with a Microsoft Windows formatted CD containing copies of all raw data, inspection results, and other information collected during the test (see example test reports).
Please take a few moments to tell us more about your device and test requirements in our short questionnaire, and we will be happy to provide you with a quote.