Anatomical relation between the accessory process and pedicle in the lumbar vertebrae

Area of Science:

• Orthopedics
• Neurosurgery
• Anatomy

Background:

• Pedicle screws are crucial in spinal surgery, with insertion points typically based on anatomical landmarks like the mammillary and transverse processes.
• Limited morphological data exists regarding the relationship between the accessory process and the pedicle, hindering its use as a surgical landmark.

Purpose of the Study:

• To clarify the morphological relationship between the accessory process and the lumbar pedicle isthmus.
• To establish a new anatomical basis for pedicle screw insertion using the accessory process as a landmark.

Main Methods:

• Recruited 50 cases diagnosed with lumbar intervertebral disc herniation using 3D CT scans of lumbar vertebrae.
• Identified the pedicle isthmus in transverse and sagittal planes.
• Measured angles and distances from the accessory process tip to the pedicle isthmus.

Main Results:

• In the transverse plane, the optimal trajectory from the accessory process tip through the pedicle isthmus is 20 (±6.6) degrees medially.
• In the sagittal plane, the trajectory is 5 (±4.3) degrees cranially.
• The distance from the accessory process tip to the pedicle isthmus is 1.5 (±0.3) cm.

Conclusions:

• The study provides quantitative anatomical data defining the relationship between the accessory process and the pedicle isthmus.
• This research establishes the accessory process as a viable anatomical landmark for guiding pedicle screw placement in spinal surgery.