Needle entry point:

The intersection of 5 mm below the horizontal line of the upper edge of C2 axis lamina and 7 mm outside the medial edge of spinal canal;

The intersection of the upper-middle horizontal line 1/4 and the vertical line 1/4 behind C3-6 side block;

The intersection point between the upper 1/4 horizontal line and the midpoint vertical line on the back of C7 side guard is slightly higher;

Angle: C2 inclines 30 degrees in the sagittal plane and 20 degrees in the horizontal plane;

The sagittal plane of C3-6 is inclined at 40-45 degrees, and the horizontal plane is parallel to the endplate;

The C7 sagittal plane is inclined at 40-45 degrees, and the horizontal plane is parallel to the endplate. The screw diameter (mm) is 3.5 cortical bone screws, and the nail penetration depth (mm) is 18-20, and the nail penetration does not exceed 80%.

After determining the nail entry point, first bite the cortical bone that falls into the nail entry point, open the opener, and the pathfinder will slowly enter with constant force. In cancellous bone, the resistance should be small and uniform. If the resistance is large, you may encounter cortical bone. You have to pull out the Pathfinder, take out the bitten spinous process, trim the osteogenic strip and fill it in the nail canal. If you use Pathfinder again, it will be easy to control the direction and avoid slipping into the original nail path. Before entering the nail, the probe must be used to detect the obvious bone sensation on the four walls of the nail channel, and then the screw must be slowly screwed in after confirming that the nail channel is in the pedicle.