Wear and fatigue testing is performed to validate hip implant durability and performance over an extended period of time. Range of motion, axial push-in/out, modular connection strength, component interlock strength, and assembly/disassembly force properties are also evaluated by static testing.
Hip stem fatigue testing, governed by ISO 7206-4 Partial and total hip joint prostheses Part 4: Determination of endurance properties and performance of stemmed femoral components, applies an axial load to an implant that has been potted in such a way as to represent loosening of the implant proximally. The orientation translates axial load into a combination of compression, torsion, and bending stresses on the stem of the specimen. Tests typically run to 5M cycles and must meet the 2,300 N (517 lbs) load requirement.
Femoral neck fatigue testing, outlined in ISO 7206-6 Implants for surgery – Partial and total hip joint prostheses Part 6: Endurance properties testing and performance requirements of neck region of stemmed femoral components, simulates loads experienced by a properly fixed implant during gait. Implants are expected to withstand 10M cycles without failure and are tested at 5,340 N (1,200 lbs).
Orbital hip wear testing aims to characterize the tribological properties of a hip implant system by utilizing wear simulator technology to reproduce walking kinematics using flexion/extension, abduction/adduction, and internal/external rotation. Advanced SEM analysis and surface scanning can be performed to evaluate particulate and wear scars.
ASTM F1814 Standard Guide for Evaluating Modular Hip and Knee Joint Components provides an overview of relevant tests depending on the type of hip implant design.
ASTM F1820 Standard Test Method for Determining the Forces for Disassembly of Modular Devices provides a standard methodology for determining the attachment strength or locking mechanism strength between modular acetabular shell and liner.
Wear and fatigue testing is performed using a variety of MTS and custom servohydraulic and electromechanical equipment.
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 peak and valley data throughout the duration of the test. MDT engineers monitor the tests daily and evaluate other factors such as cement integrity.
MDT offers several inspection and monitoring methods including:
• High speed video inspection of devices or fixture validation
• Visual Inspections
• Fretting and corrosion testing of modular components
• Digital and optical analysis
• SEM particulate analysis
• Topographical surface scanning
• Metallurgical services
• Failure analysis
Tests are conducted in accordance with ANSI/ISO/IEC 17025-2005. In compliance with this standard, MDT test reports include comprehensive documentation and a 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, and 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.