Fig. 2

a Measure the angle between the line of the midpoints of the two cross-pins and Blumensaat's line on the postoperative image. b Mark the direction of the cross-pin on the postoperative image. c Measure the angle between the direction of the cross-pin and the line along the lowest point of the posterior side of the medial and lateral femoral condyles on the postoperative image. d Measure the mediolateral diameter of the femoral condyle on the image. e Measure the anteroposterior diameter of the lateral femoral condyle on the postoperative image