A new ASTM International standard will provide a consistent method for analyzing hip stems used in hip replacement surgery. The new standard, ASTM F2996, Practice for Finite Element Analysis (FEA) of Nonmodular Metallic Orthopaedic Hip Femoral Stems, was developed by Subcommittee F04.22 on Arthroplasty, part of ASTM International Committee F04 on Medical and Surgical Materials and Devices.
“ASTM F2996 was developed to harmonize the method by which finite element models are performed, as comments from regulatory agencies indicated many different methods were used by industry,” says Jeffrey Sprague, project manager, Smith and Nephew, and an F04 member. Sprague and Walter Schmidt, senior manager, modeling and simulation, Stryker Orthopaedics, co-chaired the task group that developed F2996. The new standard will allow for accurate comparisons to be made among different companies and researchers.
ASTM F2996 establishes requirements and considerations for the development of finite element models used in the evaluation of non-modular metallic orthopaedic hip stem designs. Procedures for performing model checks and verification are provided to determine if the analysis follows recommended guidelines. Testing with such models can predict static implant stresses and strains. Results from testing to F2996 will establish worst-case size for a particular implant.
Sprague notes that F04.22 is also currently working on a proposed new standard that will provide a finite element guide for knee femoral components. Companies and laboratories that design and test such components are encouraged to participate in this standards developing activity.
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