Design and analysis of a composite osteosynthesis implant

Abstract

According to recent studies in the medical field that have investigated the biological mechanisms of bone healing, it is believed, that the mechanical properties of bone fixation plates (particularly the bending stiffness) should be adaptable to the individual needs of the host bone. Furthermore, the implant should reduce its stiffness in the course of the reconsolidation process in order to subsequently introduce load to the buttressed extremity. In consideration of the biological healing mechanisms of bone, an adaptable composite implant was designed for internal fracture treatment in orthopaedics and casualty surgery and tested in-vitro. The implant aims at the stabilisation of highly loaded extremities such as the lower limbs. Ei order to generate a better understanding of the spectrum within which the bending stiffness and correlated stiffness decay can be adjusted, a finite element model was developed. By means of this design tool, plates with varying fibre volume fraction and laminate architecture can be assessed prior to the actual implant production. Affixing the implant to a bone-like structure its behaviour can be simulated in consideration of specific patient data such as body weight and age. Furthermore, other implant designs Iike the Limited Contact-Dynamic Compression Plate (LC-DCP) can be modelled and characterised. Ei the course of the experimental studies as well as the subsequent simulation work it became evident, that the structural properties of composite implants can be adjusted within a wide window. Consequently these implants provide optimum prerequisites to serve the specific needs of the patient. Incorporating a biodegradable component into the body of the composite implant a gradual stiffness decay and thus a subsequent Ioad transfer from implant to bone was achieved.