Accuracy of navigation: a comparative study of infrared optical and electromagnetic navigation.

We evaluated the accuracy of navigation systems for measuring the mechanical axis in patients undergoing total knee arthroplasty and in the synthetic bone model. Infrared optical and electromagnetic navigation systems were compared. Both systems were found to be accurate and reproducible in an experimental environment. However, the accuracies of both systems were affected by erroneous registration, and the optical system was found to be more reproducible. In clinical situations, the mean difference was 1.23 degrees, and difference greater than 3 degrees occurred in 15% of clinical trials. These discordances may have been due to ambiguous anatomic landmarks causing registration errors and the possibility of electromagnetic signal interference in the operating room.