Fig. 1.

Line drawings on axial computed tomography scan showing landmarks for determining skin entry point. Line C is drawn along the lateral border of vertebral body at opposite side. Line B is drawn along the outmost part of pedicluar ring at same side. Line A is apart from line C by 2.5 times of β distance, irrespective of levels. Ideal trajectory of far lateral approach in single balloon kyphoplasty should start from the point a (entry point), through the point b (the outmost border of the ipsilateral pedicle ring), and the point c (the imaginary point where the horizontal line drawn along the anterior cortex meets the vertical line along the contralateral border of the fractured body) is the target. α : a distance between the line A and C, β : a distance between line B and C.