Aetiology

The aetiology of cervical spondylolisthesis involves:

• congenital non-fusion of the dens with the axis - the dens and axis are attached only by fibrous tissue. The fibrous band slowly stretches allowing the dens, and with it, the atlas and skull, to slide gradually forwards.
  
  
• inflammatory softening of the transverse ligament of the axis - due to an inflammatory lesion in the upper part of the neck, for example, in rheumatoid arthritis, or to infection of the throat or glands. This permits the atlas to slide forwards upon the axis.
  
  
• instability from rheumatoid arthritis or previous injury
  
  
• traumatic spondylolisthesis - fracture through the pars interarticularis, especially, C2.