Philippe MERLOZ (Grenoble)
The use of Computer Aided Orthopaedic Surgery (CAOS) technology for Total Knee replacement (TKR) allow a reduction of outliers in mechanical axis alignment (1/4 versus 1/10 in navigated / conventional TKR). Most of the systems are image free navigation systems (75%). With CAOS technology the average operative time is 20 minutes longer (on the average), but there is no additional blood loss. As compared to conventional procedure, CAOS technology makes no difference in functional / pain scores and no additional navigation-related complications, but allow in-vivo intraoperative quantitative measurement (axis, soft tissue balancing etc...). Cost, additional time, and learning curve might very well be compensated by the significant outlier reduction.
From a clinical point of view, the results of TKA performed using manual instrumentation have been reported by many authors to be excellent for a very large proportion of patients. It has, therefore, been difficult to conceive in what ways computer-assisted TKA’s could improve functional outcomes. Most of the studies indicate a consistent reduction in outliers in most measured parameters of functional outcomes. A reduction in outliers was consistently associated with the use of computer-assisted techniques, regardless of the implant system used. Many studies indicate that the consistency of alignment achieved with computer-assisted techniques results in a corresponding consistency in clinical functional outcomes.
From a methodological point of view, we need more through and systematic reporting, uniform reporting criteria per procedure and to define the best level of evidence (gold standard), with prospective, randomize, multicentric, and comparative studies. At the present time, we have no informations on long term follow-up (PE wear, longevity...).
Computer Assisted Knee Arthroplasty
In Lemaire R, Bentley G, Scott J, Horan F, Khanduja V. Eds.
European Instructional Course Lectures
The British Editorial Society of Bone and Joint Surgery, edit. London, 2007, Vol 8, 154-159