100 patients scheduled for primary total knee arthroplasty were randomized to intraoperative placement of the tibial component using either a portable, accelerometer-based navigation device (KneeAlign, OrthoAlign, CA) or using conventional extramedullary guides. Radiographic outcome in patients was assessed at approximately 6 weeks post-surgery. The results indicated that the number of outliers and absolute deviation in tibial component alignment and posterior tibial slope were significantly reduced in the group treated with the KneeAlign device relative to patients who received placement with an extramedullary guide. No difference between groups were noted for femoral component alignment or overall mechanical alignment.