PURPOSE: We wanted to examine the accuracy of the lower limb alignment and implant positioning that was obtained with using the electromagnetic (EM) navigation technique. MATERIALS AND METHODS: We examined 64 patients who underwent 100 TKAs with using EM navigation technique from July 2006 to February 2007. Sixty-two patients who underwent 100 TKAs with using the conventional technique between August 2005 and July 2006 were used as controls. We assessed the mechanical axis and the alpha, beta, gamma and delta angles in the postoperative radiograph of each patient and we compared them among the two groups. RESULTS: The patients in the EM navigation group achieved better accuracy than did the conventional group in terms of the postoperative mean mechanical axis (1.2degrees vs. 2.3degrees). Less variations in the coronal femoral component and the tibial component angle were observed in the navigation group (femur: 89.3degrees vs. 88.7degrees; tibia: 89.6degrees vs. 89.3degrees, respectively), although the difference in the coronal tibial component angle was not significant. CONCLUSION: The use of EM navigation technique in TKA does not always guarantee the precise alignment of the mechanical axis in all planes, as compared to using the conventional technique. Yet it is useful for obtaining better coronal alignment of the femoral component.
Arthroplasty ; Axis, Cervical Vertebra ; Humans ; Knee ; Lower Extremity ; Magnets ; Osteoarthritis