Aetiology and pathology

Normally, slipping of one vertebrae upon the another is prevented by the engagement of its articular process with those of the segment next below it. A failure of this check mechanism produces spondylolisthesis. This may arise in five situations:

• slipping at a spondylolysis of the pars interarticularis:
  • caused by a fatigue fracture
  • the most common form of spondylolisthesis
    
    
• degenerative osteoarthritis:
  • mechanical wear of the posterior facet joints may result in vertebral slipping
  • the main problem is degenerative disc disease
  • it is most most common in women over the age of 55 years
    
    
• dysplastic:
  • a congenital deficiency of the posterior facet joints
  • this is most common at the lumbo-sacral joint allowing the L5 vertebra to slip forwards off S1
  • it is a rare condition, more common in girls than boys
  • complete displacement may produce a cauda equina syndrome
    
    
• trauma - very rarely, spondylolisthesis may result from an acute traumatic fracture, or a pathological fracture through a tumour
  
  
• pathological - weakening of the pars interarticularis by tumours and osteoporosis