Evaluation of accuracy of an electromagnetic computer-assisted navigation system in total knee arthroplasty

Abstract

The objective of this study was to develop a method to assess the accuracy of an electromagnetic technology image-free navigation system for total knee arthroplasty in a leg with normal or abnormal mechanical alignment. An acrylic phantom leg was constructed to simulate tibia and femur deformation. Determination of actual leg alignment was achieved using a digital caliper unit. In the setting of normal alignment, the mean error of the system characterised as the difference between the measured computer navigation and digital caliper angles ranged between 0.8°(frontal plane) and 1.5°(lateral plane). In the setting of abnormal alignment, the mean error ranged between 0.4°(frontal plane) and 1.6°(lateral plane). Deformity had no demonstrable effect on accuracy. The study demonstrates satisfactory in vitro system accuracy in both normal and abnormal leg mechanical alignment settings.Résumé Le but de cette étude était d'évaluer les techniques de navigation sans image par technologie électro-magnét-ique au cours des prothèses totales du genou. Un fantôme acrylique de membre inférieur a été construit de façon à simuler la déformation du tibia et du fémur. La différence moyenne entre la mesure par computer et la mesure instrumentale est de 0,8°dans le plan frontal et de 1,5°d ans le plan latéral. Dans les cas de mauvais alignements la moyenne a été de 0,4°dans le plan frontal et de 1,6°sur le profil. Cette étude in-vitro montre que ce système est fiable aussi bien pour un membre inférieur normalement axé que désaxé.

Electromagnetic Navigation in Total Knee Arthroplasty—A Single Center, Randomized, Single-Blind Study Comparing the Results With Conventional Techniques

“…Our experience was that in the presence of ferrous materials the system would go 'blind' and prior to loss of signal, no unexplained change in the system readout values was noted. Other in vitro and in vivo studies looking at the results of electromagnetic navigation have confirmed that system accuracy is not problematic, with good results comparable to infra-red systems [35,40,41]. Two clinical studies have compared the electromagnetic technique directly with traditional infra-red navigation systems and found similar, high degrees of accuracy [42,43], although the numbers in these studies were small.…”

“…Some of our increased time was associated with data collection for the study to assist in post-operative analysis but the majority results from array insertion, landmark registration and inevitable, although uncommon software glitches. This increase in surgical time allied to the additional costs of hardware, software and disposables required to carry out the surgery all put pressure on navigation techniques to deliver better surgical outcomes [11,[14][15][16][17]19,[30][31][32][33][34][35][36].…”

The effect of pelvic movement on the accuracy of hip centre location acquired using an imageless navigation system

“…For this reason a different, independent system (3D measurement device) was used in this study to assess the precision of the navigation system. Pitto et al [17] used the same method to assess the accuracy of an infrared CAS navigation system in legs with abnormal mechanical axes and to determine accuracy of CAS based on electromagnetic technology [18].…”

Assessment and validation of CT scanogram to compare per-operative and post-operative mechanical axis after navigated total knee replacement

“…Given the precise algorithm which allows accurate measurement of mechanical axis, computer navigation is now considered to be the new gold standard for the purpose. Recently, Graydon et al [6] evaluated the in vitro use of a navigation system based on electromagnetic technology, reporting accuracy similar to infrared-based navigation systems for total knee arthroplasty.…”