Lumbar disk surgery for a ruptured or herniated disk is the most commonly performed surgical procedure for low back pain with pain radiating into a leg. A satisfactory result from lumbar disk surgery is as much dependent on proper patient selection as the actual performance of the surgery. A patient whose symptoms, examination and tests do not point to a specific ruptured disk may not improve with surgery.

Anatomy

• The lumbar spine and pelvis (the low back) supports the entire upper body
  
• The lumbar spine allows bending forward and back and to twist at the waist
  
• The normal lumbar spine is composed of five building blocks called vertebrae that sit on the sacrum, which is the back part of the pelvic bone (Figure 1)
  
• Each vertebra is constructed of a body, lamina and pedicles, which surround an opening, the spinal canal (Figure 2)
  
• Through the spinal canal pass the nerve roots that emerge from the end of the spinal cord and go to form the nerves to the legs. The roots float in fluid (cerebrospinal fluid) and are contained within a fibrous sac called the dura (Figure 3)
  
• Separating any two vertebral bodies is a soft elastic material called a disk. The disk is composed of two parts, a soft center called the nucleus and a tough outer band called the annulus. (Figure 4) There are five lumbar disks that are designated by the number of the lumbar vertebra just above the disk
  

Figure 1	Figure 2

Figure 3	Figure 4