Computer-assisted technology creates a new approach to total knee arthroplasty (TKA). The primary purpose of this technology is to improve component placement and soft tissue balance. We asked whether the use of navigation techniques would lead to a narrow range of implant alignment in both coronal and sagittal planes and throughout the flexion-extension range. Using a prospective consecutive series of 57 navigated TKAs, we assessed intraoperative knee measurements, including alignment, varus-valgus stress angles in extension, and varus-valgus angles from 0° to 90° of flexion comparing postimplant with preimplant. We found fewer outliers with coronal (100% of TKAs within ±2°) and sagittal (0% of TKAs with fixed flexion greater than 5°) alignment, soft tissue balancing (mean varus and valgus stress angles -3.2° and 2.3°; range, -5° to 5°), and mean femorotibial angle over flexion range 0° (-0.2°; range, -1° to 2°), 30° (-0.2°; range, -5° to 4°), 60° (-0.5°; range, -5° to 7°), and 90° (-0.2°; range, -5° to 10°). This technology allows a narrow range of implant placement and soft tissue management in extension. We anticipate improved ultimate patient outcomes with less tissue disruption.

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