EFFECTS OF INCORRECT ACQUISITION OF ANATOMICAL LANDMARKS ON IMAGE-FREE NAVIGATION-ASSISTED TOTAL KNEE ARTRHOPLASTY

Background The study was designed to assess whether, and to what extent, incorrect acquisition of anatomical landmarks during navigated total knee arthroplasty affects the accuracy of implant positioning. Methods An artificial model of the lower limb was used to simulate a navigated total knee arthroplasty. The anatomical landmarks necessary for navigation were identified and the procedure performed as usual. Navigation was then repeated after having collected the anatomical landmarks with an error of 10mm from the reference points. The spatial orientation of resulting bone cuts was registered with the navigation system and compared with that of bone cuts performed with correct anatomical landmarks. Results Compared with the reference cuts, the incorrect collection of anatomical landmarks led to changes in the coronal alignment of tibial and femoral cuts within 18 and 2.28, respectively, and in sagittal alignment within 1.58 and 2.18, respectively. Incorrect landmarks of the medial and lateral epicondyles led to errors in the rotation of the epicondylar axis of 10-178. Conclusions When computer-navigation is used, the coronal and sagittal alignment of total knee arthroplasty may be improved by an accurate collection of anatomical landmarks. Axial rotation of the femoral component should be assessed using other techniques in addition to the palpation of femoral epicondyles