Cutting error of the distal femur in total knee arthroplasty by use of a navigation system.

The aim of this study was to evaluate the alignment of the distal femoral cutting surface using a navigation system to determine the accuracy of bone cutting. We evaluated 20 knees in 20 patients. After cutting the distal femur, the cutting surface was validated using the navigated cutting block adapter, and the angular difference between the cutting surface and that preoperatively planned in the sagittal and coronal planes was recorded. The average error of all knees was 1.6° ± 2.2° in extension, and 14 (70%) of 20 knees were cut in an extended position. Our tendency is to cut the distal femur in an extended position with the first femoral cut in the sagittal plane.