Spondylolysis and Spondylolisthesis

Diagram of a human spine showing the grades of SpondylolysisA spondylolysis is a type of broken bone in the spine.  Both struts holding the front and back parts of the bone together break. The back part of the vertebral bone (the lamina) separates from the front part (the body).  Because of the broken bone, the spine can become unstable and the body can slip forward.  The slippage is called a spondylolisthesis. 

Spondylolisthesis is graded.  Higher numbers indicate a more severe problem.  There are five grades, or levels, of severity. 

To determine the grade of spondylolisthesis, or slippage, the disc is divided in quarters.  The grade is equal to the number of quarters of slippage.  If there is no slippage, the grade is zero.  If the slippage is equal to one quarter of the total width of the disc, the slippage is grade one.  If the slippage is three quarters of the width of a disc, it is a grade three spondylolisthesis.  If the slippage is more than four quarters (the whole disc space) then it is called a grade 5.  In a grade 5 spondylolisthesis, the spine is completely dislocated.

Diagram showing spondylolysis grade zero (0) Diagram showing spondylolysis grade one (1) Diagram showing spondylolysis grade two (2)  
  Diagram showing spondylolysis grade three (3) Diagram showing spondylolysis grade four (4) Diagram showing spondylolysis grade five (5)

Go to the next chapter on symptoms, starting with back pain.

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Last modified: 07/27/08