Modular Connection Fatigue Testing of a Linked Semi-Constrained Total Elbow Prosthesis

Introduction: The evolution of third and fourth generation linked, semi-constrained total elbow replacements (TER) have employed an increasing use of modularity to facilitate component linkage and inter-operative flexibility. In general, modular connections (MC) used in orthopedic devices may carry inherent risks of adverse events resulting from component fracture, loosening, micromotion, fretting and corrosion [1]. Specific to TER, no peer-reviewed literature could be located on this subject. However, a search of the US Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience Database (“MAUDE”) suggests that a number of TER reported adverse events have been associated with set screw fracture or loosening and concomitant component disassociation requiring revision surgery [2]. Further, no international standards exist to evaluate modular connection fretting fatigue (MCF) of modern TER. Therefore an MCF test method to characterize the fatigue strength, fretting corrosion behavior and resistance to screw-loosening was developed and is applied here to the NexelTM Total Elbow (Nexel) (Zimmer, Inc.).