Computer-assisted surgery: A teacher of TKAs R. Iorio, D. Mazza ⁎, G.Bolle, J. Conteduca, A. Redler, F. Conteduca, A. Ferretti Orthopaedic Unit and “Kirk Kilgour” Sports Injury Centre, S. Andrea Hospital, University of Rome “Sapienza”, Italy abstract article info Article history: Received 10 January 2012 Received in revised form 23 June 2012 Accepted 25 June 2012 Keywords: TKA Overall alignment Computer-assisted surgery Learning curve Introduction: The hypothesis of this study is that computer-aided navigation experience could improve the ability to better place components in the coronal plane and to improve visual/spatial awareness based on the ability of navigation to provide instant feedback. The purpose of this study is to demonstrate the educa- tional role of the navigation system to obtain a better alignment of the prosthetic components with standard instrumentation after a computer-aided navigation experience. Materials and methods: One hundred fifty patients were operated by the same surgeon, with more than 5 years experience with TKA. They were equally divided in three groups: group A (operated with non-navigated tech- nique by surgeon without computer-assisted experience); group B (operated with computer-assisted surgery by the same surgeon); group C (operated with non-navigated technique by the same surgeon after the computer-navigated experience). We evaluated by full-length weight-bearing radiographs the overall alignment of the lower limb in the coronal plane. The optimum placement of the components was considered when the angle was within the limits of ±3° varus/valgus on the coronal x-rays. Comparison between groups was done using one-way ANOVA followed by post hoc Bonferroni test and Pearson chi-square statistics for proportions of optimum placement (P b 0.05). Results: In the group A 34 patients (68%) had the optimum placement on the coronal x-rays; in the group B they were 46 (92%) and in the group 41 (82%). The difference is statistically significant in comparing group A and Group B (b 0.001), group A and group C (P =0.04), but not for group B and C (P = 0.2). Conclusion: We believe that the navigation system has an educational role to improve the ability of surgeon of positioning prosthetic components precisely in the coronal plane. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Accuracy of implantation is an accepted factor for a successful out- come in total knee replacement. [1–3] Component malalignment is associated with detrimental effects such as early loosening, polyeth- ylene wear and pain relief. [4–6]. Varus or valgus malalignment has been described as the commonest cause of early loosening. Several studies [7,8] have suggested that alignment errors of > 3° are associ- ated with early failure and less satisfactory functional outcome. Navigation systems have been developed to address this issue by the careful identification of the anatomical planes and the overall alignment of the lower limb. [9] Computer assisted system (CAS) has been devel- oped to improve on the limitations inherent in mechanical instrumen- tation used for total knee replacement surgery [10] and several after studies [11–13] have demonstrated that computer-aided navigation improves accuracy of component positioning and decreases the blood loss [14]. The hypothesis of this study is that computer-aided navigation ex- perience could improve the ability to place components in the coronal plane. We could speculate that the use of the computer assisted tech- nique can improve visual/spatial awareness based on the ability of navigation to provide instant feedback. 2. Materials and methods Between March 2008 and June 2011, 150 patients with primary gonarthrosis were selected for unilateral TKR and operated with an uncemented posterior cruciate ligament sacrificing mobile bearing TKA (LCS De Puy Orthopaedics, Warsaw, IN) by the same surgeon, with more than 5 years experience with 250 TKAs (100 TKAs as first surgeon). Patients were equally divided into three groups: • Group A: operated with non-navigated technique by surgeon before computer-assisted experience; • Group B: operated with computer-aided navigation by the same surgeon; The Knee 20 (2013) 232–235 ⁎ Corresponding author at: Via Grottarossa 1035, Rome (RM), Italy. Tel.: +39 06 33775344; fax: +39 0633775917. E-mail address: daniele.mazza@hotmail.it (D. Mazza). 0968-0160/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.knee.2012.06.009 Contents lists available at SciVerse ScienceDirect The Knee