Angled orthopaedic fixation devices or hip compression screws are used to treat fractures in the metaphyseal areas of long bones. Loading creates a compression bending load at the angled portion, which must be evaluated for strength and stiffness by researchers when comparing materials and designs, and also by the surgeon to predict performance.
Fatigue life over a specific time or loading range must also be determined. For these reasons, the test fixture must simulate compressive loads experienced by the angled portion of the plate as a result of body weight.
Testing is based on standard ASTM F384 - Standard Specifications and Test Methods for Metallic Angled Orthopedic Fracture Fixation Devices. For static testing, a ramped compression load is applied until the fixation device plastically deforms or a set deflection is reached. The objective is to determine the static bending stiffness of the plate. Four-point bending and fatigue testing, using an ElectroPuls™ Test Instrument or 8870 Fatigue Testing System, is also necessary to accurately evaluate the fixation device. The fixture is designed to work with or without a saline bath and can be adapted to suit a variety of specimen sizes and geometries.