Development of an experimental apparatus for testing a total knee prostheses focused on Mexican phenotype

Abstract

This work was focused on the design and development of an experimental loading rig adapted to make experimental tests of total knee prosthesis. Location of contact points due to rotation and translation of simultaneous movements was analyzed carefully. This takes place between the femoral component and the polyethylene insert, since this is one of the main obstacles in the design of devices adapted to reproduce movements similar to healthy knee. In this apparatus, contact tests can be made for flexion angles of 0 to 140° with 10° stepping. Also, two positions, 5 and 15°, are located where axial load on the knee becomes higher, which allows the finding of critical contact stress areas in the polyethylene insert using a Fuji PRESCALE™ film or Tkscan K-SCAN™ that are sensible to pressure. Design process involves computational programs like SOLID WORKS™ andANSYS V12™, in order to develop three-dimensional (3D) and finite element (FE) models to evaluate operational and structural behaviour. The main advantages of this experimental simulator are its design simplicity, easy construction and low cost. So a better design apparatus was obtained for the experimental tests, focused on the development of a customized total knee prosthesis for the Mexican phenotype, as it allows the assembly of components with different dimensions and geometry considering a few sizes of total knee replacements (TKRs), based on a model SCORPIO II™ of STRIKER Co., and using a femoral insert size 9R, which is the most applied in Mexican healthy institutions. Key words: Experimental simulator, total knee prosthesis, phenotype, contact mechanics, mechanism of wear.