The anatomy of pedicle scews prove that the height is bigger its width further, and that makes the change of (SSA) have more space than the (TSA).

• 椎弓根解剖证实椎弓根的高度远大于它的宽度这使椎弓根螺钉的矢状面成角（SSA角）的改变相对水平面成角（TSA角）有更大的空间。