(iv) Computer-assisted knee replacement techniques

SummaryImplant alignment errors are associated with inferior results after total knee arthroplasty. Computer assistance supplements mechanical instrumentation by the addition of measurements which are used to locate landmarks, direct surgical tools and thereby better align prosthetic components. Modern navigation systems are based on infrared-light tracking or, more recently, on electromagnetic guidance. After initial scepticism a variety of systems have found acceptance and a remarkable number of clinical and laboratory studies have been published. There appears to be a consensus that computer assistance brings about a significant reduction in the number of outliers and improved varus/valgus, rotation and slope alignment of components. Most studies conclude with the prediction that individual and cumulative improvement in component alignment will ultimately lead to better long-term results. The controversies surrounding routine use of computer assistance in knee arthroplasy are discussed. Data analysis founded on navigated dynamic intra-operative investigation will possibly be the key to future implant design and alignment.