Analysis and Evaluation of Limb Alignment in Total Knee Replacement

Abstract

Numerous factors contribute to success of a total knee replacement (TKR); including surgical instruments, operational methods, positioning of prosthesis, cementing techniques, surgical experience and limb alignment. Limb alignment of±30 has been rationally thought to be an acceptable alignment and clinical studies have to certain extent validated these assumptions. However these alignment boundaries still remain a hypothesis, as±30 is an arbitrary value; therefore need validation. In this work, the main objective was to analyze the pattern of relative stress distribution in TKR if the axial alignment is gradually increased or decreased including the range of±3°. This work shows an application of digital modeling of limbs and implants, where CAD has been applied to design and assembly of femur, tibia and knee implants. The analysis was carried out at different alignment positions in Ansys workbench 14.0. It was found that within±4° the rise in stress across the model surfaces is not much, however beyond±5° there is dramatic increase in pressure and pressure imbalance with every degree of change. This investigation will be useful for surgeons in TKR surgeries and possibly underlines the importance of use of computer assisted surgeries to obtain more accurate alignment and more ever to avoid the outliers outside±5° which might cause grater imbalance and early failure of implants. © 2013 Copyright CAD Solutions, LLC.