Pedicle screw entry points and angulation in the thoracic spine can be divided into four groups based on the relation of the pedicle with the articular facets and the transverse process.
The screw angulation is slightly medial and caudal.
The screw angulation is vertical or slightly lateral .
The entry point of the pedicle screw is defined as the confluence of any of the four lines:
A pedicle probe is used to navigate down the isthmus of the pedicle into the vertebral body.
The appropriate trajectory of the pedicle probe in the cranial caudal direction occurs by aiming for the contralateral transverse process.
Thereby paralleling the screws to the superior endplate.