2017 Volume 36 Issue 1 Pages 27-32
Objective: Accurate and precise bone incision and implantation are important for good clinical results in total knee arthroplasty (TKA). However, it is said that approximately 10-20% of malalignments occurs with conventional devices. Navigation is one of the tool to prevent malalignment. We estimated the accuracy of locating the calculated center of the ankle in two different navigation systems (precisioN and iASSISTTM) in this study.
Methods: Thirty patients who received TKAs in our hospital were included in this study. Preoperative computed tomography data were used to characterize the shape of each tibia and to establish the true centre of each ankle. The virtual center of each ankle was set as the midpoint of the bilateral malleoli in iASSISTTM, while it was set at 44% of spots from the medial malleoli in precisioN, respectively.
Results: Compared with the true ankle center, the ankle center of precisioN was present 1.9 mm medial, 2.7 mm posterior, and 3.2 mm distal, whereas the ankle center of iASSISTTM was present 1.6 mm lateral, 3.5 mm posterior, and 3.2 mm distal without skin thickness, respectively. Also, the ankle center of precisioN was present 2.4 mm medial, 2.7 mm posterior, and 3.4 mm distal, whereas the ankle center of iASSISTTM was present 1.7 mm lateral, 3.6 mm posterior, and 3.9 mm distal with skin thickness, respectively.
Conclusion: In this study, the error of recognizing the centre of the ankle was less than 1 degree in two different image-free navigation systems. If adequate reference points can be digitized, the application of different navigation systems can be utilized with accuracy intraoperatively.
