Transpedicular Screw Fixation

KEY FACTS

Terminology

• Pedicle screw: Most common implant in spine surgery

  • High rigidity and resistance to pullout

  • Engages all 3 columns of spine

  • Resists motion in all 3 directions

• Used in wide variety of procedures

  • Maintain spine alignment while fusion occurs

  • Maintain reduction after fracture

  • Maintain correction of deformity

Procedure

• 3 common techniques

  • Free hand

  • Fluoroscopy based

  • Computer assisted (navigation) either 2D or 3D

    • –

      Safe and reproducible

    • –

      Incidence of exposed screws outside of pedicle decreased with 3D navigation from 12% to 7%

Outcomes

• CT is gold standard for assessment of pedicle screw position

• Screw malposition rates vary widely (0.5-13%)

• Medial wall penetration

  • Pedicle wall penetration (10-20% overall incidence)

  • Neural injury to root or cord (< 1%)

  • CSF leak if dural laceration

• Anterior or lateral penetration

  • Visceral injury, esophageal perforation

  • Pneumothorax

  • Aortic or segmental vessel penetration

  • Some canal intrusion is asymptomatic (< 2 mm)

• Pedicle fracture

• Pedicle plow

  • Occurs during vertebral rotation in scoliosis surgery

  • May cause aortic abutment of screw