Abstract
Total knee replacement is an increasingly popular operation for end stage knee arthritis. In the majority it alleviates pain and improves function. However up to 20% of patients remain dissatisfied, even with well-aligned and secure implants. Restoration of a neutral mechanical axis has traditionally been strived for, to improve both function and implant survival and there is historical data to support this. More recently this view has been questioned and some surgeons are trying to improve the function and outcomes by moving away from standard alignment principles in an attempt to reproduce the kinematics of the pre-arthritic knee of that individual. Others are using computers, robots and patient specific guides to improve accuracy. This article aims to review the traditional alignment concept and the newer techniques, along with the evidence behind it.