Comparison of limb and component alignment using computer-assisted navigation versus image intensifier-guided...

Total knee arthroplasty was performed in 282 knees with image-free navigation (group A) and in 185 with optimized conventional technique (group B). Mean postoperative mechanical axis of the limb was 179.7 degrees in group A and 179.1 degrees in group B (P < .002). There was a higher percentage of knees in group A that had restoration of mechanical axis to +/-1 degrees, +/-2 degrees, and +/-3 degrees of neutral (P < .0001). There were 9.2% outliers (+/-3 degrees) in group A and 21.6% outliers in group B (P < .0001). For knees exceeding 20 degrees varus, there was no significant difference between the mean mechanical axes in the 2 groups. Both components were aligned within 3 degrees of neutral in 90.8% of the knees in group A and 76.2% of the knees in group B (P < .0001).