Imaging

• Magnetic resonance imaging (MRI)
  
• Computed tomography myelogram if MRI inconclusive with artifact
  
• Computed tomography allows pedicles and vertebral bodies to be measured accurately

Operative Planning

• Patient counseling
  
  
  
  
  • Cerebrospinal f luid leaks
    
  • Pseudoarthrosis
    
  • Spinal cord injury
    
  • Nutrition to optimize wound healing

Equipment

• Basic spine tray
  
• High-speed drill (Midas Rex with AM-8 and/or AM-35 bit)
  
• Kerrison punches

• Headlight
  
• Loupes
  
• Microscope (optional)
  
• Bipolar cautery and Bovie cautery
  
• Consider intraoperative fluoroscopy
  
• Consider intraoperative navigation (Stealth)
  
• X-ray compatible table
  
• Cell Saver

Anesthetic Issues

• Electrophysiologic monitoring (optional but should be considered in the thoracic spine)
  
• As for posterior lumbar transforaminal arthrodesis

Positioning

• On a standard operating room table, the patient is placed prone on chest rolls
  
• Arms abducted at 90 degrees and brought forward

Depilation

• As for posterior lumbar transforaminal arthrodesis

Planning of Sterile Scrub and Preparation

• As for posterior lumbar transforaminal arthrodesis

Planning of Incision

• May be based on either the 12th rib or counting up from the sacrum
  
• Correlate with preoperative studies to ensure only five lumbar vertebral bodies

Exposure

• Similar to posterior lumbar approach

Instrumentation Options

Instrumentation Technique for Thoracic Pedicle Screw

• Pedicle dimensions: smallest in midthoracic spine
  
• Entry points are dif ferent in upper, mid-, lower thoracic spine
  
  
  
  
  • T1–T3: entry is midpoint of transverse process (TP)
    
  • T4–T6: entry point is superior one third of TP
    
  • T7–T10: entry point is superior to TP
    
  • T11–T12: entry point is cephalad to midpoint TP
  
  
• Thoracic pedicle screw placement
  
  
  
  
  • Freehand technique
    
    
    
    
    • Decorticate entry point with drill
      
    • Access pedicle with Lenke probe
      
    • Undersize tap (pedicle may be dilated with serial tapping)
      
    • High torques may result in pedicle fracture
    
    
  • Decortication with drill to reveal the pedicle followed by tapping
    
  • Laminoforaminotomy
    
  • Image guidance (optional)
    
  • Fluoroscopy (optional)
  
  
• Screw sizes
  
  
  
  
  • Typically 4 to 5 mm screw into midthoracic spine
    
  • Typically 6 mm screws into T10–T12
    
  • Lengths typically 35 to 45 mm
    
  • Anatomic versus straight forward trajectories
  
  
• Normal thoracic curvature
  
  
  
  
  • Surgical goal to recreate with instrumentation
    
  • Twenty to 50 degrees T2–T12
    
  • Mean 36 degrees
    
  • Apex at T6–T8
    
  • Cervicothoracic and thoracolumbar junctions are neutral

Fusion

• Preparation of the bone graft bed with extensive decortication
  
• Minimize any soft tissue interfering with the direct onlay of graft on decorticated bone
  
• Autograft from the iliac crest

• Thoracic wedge fractures
  
  
  
  
  • Mostly anterior column disruption
    
  • If in overall balance, can consider bracing or posterior only construct
  
  
• Thoracic burst fractures
  
  
  
  
  • Anterior and middle column compromised
    
  • Consider 360 fusion
  
  
• Fracture/dislocation
  
  
  
  
  • Three column compromise
    
  • Consider 360 fusion
    
    
    
    
    • Patient age and comorbidities must be considered prior to 360 fusion
      
    • Levels to fixate with thoracolumbar junction fractures and tumors: three levels above and two levels below
      
    • May require anterior corpectomy and fusion

Closure

• Similar to posterior lumbar approach