Navigated versus Mechanical Knee Replacement: Comparison between Initial Navigated and Conventional Cases Performed by the Same Surgeon

OBJECTIVE The postoperative mechanical axis in 36 cases of total knee arthroplasty using navigated and mechanical alignment systems was evaluated and compared. All the operations were performed over the same period by the same surgeon and team, who were beginners in the navigated technique and experienced in the mechanical technique. METHODS Between 2008 and 2010, 36 total knee prostheses were performed and compared: 25 navigated and 11 mechanical procedures. Any deviation from the axis measured on the panoramic postoperative X-ray was considered positive. RESULTS The navigated prostheses produced a mean axis deviation of 1.32 degrees and standard deviation of 1.57 degrees and the mechanical, respectively 3.18 and 2.99 degrees. There was better alignment with a tendency towards a statistical difference favoring the navigated technique. CONCLUSION There were significantly more cases with axis deviation greater than three degrees using the mechanical technique. The navigated technique was incorporated by this team without additional complications and, even without experience of navigated surgery, the initial cases achieved better alignment than with the mechanical technique, and a significantly smaller number of outliers from the three-degree safety zone.