Clinical Findings

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  A 28-year-old man presented with left buttock and thigh pain having lasted for more than 1 year.

  
  
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  The VAS score was 9/10 for left leg pain and 3 to 4/10 for back pain.

  
  
• 
  

  Preoperative MRI showed a paramedian to left disk herniation at the L4-L5 level, and a CT scan also showed a soft disk ( Fig. 18.77 ).

Preoperative Plan

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  Axial MRI scans are used to determine the target point and the intended needle trajectory. The distance from the midline is ~13 cm ( Fig. 18.78 ).

  
  
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  The needle trajectory is 5 to 8 degrees in the cranial to caudal direction.

Surgical Procedures

1. 
   

   The needle insertion angle must be between 5 and 8 degrees above a horizontal line parallel to the end plate ( Fig. 18.79A,B ).

   
   
2. 
   

   The final position of the working channel is at the midpedicular line in the AP fluoroscopic view ( Fig. 18.79C ). The tip of the working channel should be half anterior and half posterior to the posterior border in the lateral fluoroscopic view ( Fig. 18.79D ).