The effect of bone healing condition on the stress of screw fixation in orthotropic femur bone for fracture stabilization

Abstract The stability on the fracture site is an important precondition for successful healing. Osteosynthesis is an alternative treatment for the stabilization of femur bone. Besides, the fractured bone experiences direct (primary) or indirect (secondary) healing which can be divided into two healing conditions (i.e. contact healing and gap healing). The healing of unstable fracture is essentially characterized by callus formation prior to healing. Understanding the stability on the fracture site is necessary to determine the parameters which will influence the implant stability. Nonetheless, there is a lack of study with regards to the influence of the osteosynthesis on the fixation strength and micro motion at of the fracture gap. Hence, for all intents and purposes, this study is aimed to investigate the influence of healing condition on the critical stress of cortex screws. Apart from that, this study is also expected to identify the yield region on cortex screws. Uninterruptedly, the results have revealed that the stress of plate fixation is significantly affected by the healing conditions. In particular, bone healing leads to a greater stress concentration on the screws, whilst the distribution is more uniform in contact healing condition. Furthermore, the results show that the different material properties at different modulus of bone healing imparted effect to the stress concentration on the screws.