Non-invasive navigation in total knee arthroplasty : a validation study

The purpose of this study was to evaluate intraoperative alignment during total knee arthroplasty using a handheld navigation system, iAssist, in comparison with conventional optical surgical navigation. Sixty-two consecutive patients were enrolled in this prospective study. iAssist was used to determine implant component positioning. Orientation of the cuts were verified using a conventional optical surgical navigation system. We compared the iAssist system with the conventional system in terms of accuracy, percentage of outliers, bias, and precision. The occurrence of component malalignment was low. Taking standard radiography as the reference, there were no relevant differences between the handheld device and optical navigation in terms of measurement of accuracy or in outlier occurrence. Bias was small for both technologies, and precision was comparable. The study provides preliminary evidence that the use of iAssist leads to satisfactory implant alignment. The results from this study imply that iAssist could be a viable alternative to conventional optical navigation.