Implicit Modeling of Screw Threads for Bone-implant Finite Element Analysis

Introduction The development and evaluation of orthopaedic devices are commonly assisted by finite element analysis [1]. Computational models are usually simplified through approximations to enable efficient simulations, without affecting the outcome of relative comparisons between different implant designs or configurations. The physical behavior of the bonescrew interface prior to osseointegration of the implant is not yet well understood [2]. Explicit modeling of screw threads with frictional contact is computationally expensive for complex bone-implant systems, while a perfectly bonded interface, which is commonly used, may be an oversimplification. The aim of this study was to develop and evaluate a technique to approximate the behavior of a finely threaded screw using a smooth cylinder with the threads implicitly represented through interfacial contact conditions.