Spondylolisthesis is the forward displacement of one vertebra on another, usually the fifth lumbar on the sacrum, or the fourth lumbar on the fifth. It may be due to a developmental defect or a fatigue fracture in a certain area of the vertebra. This defect in the pars occurs in 5-8% of the population of unknown cause, but often related to an acquired condition or as a result of repetitive stress (weight lifters, gymnasts, football lineman).

 

Spondylolisthesis can be described according to its degree of severity. One commonly used description grades spondylolisthesis, with grade 1 being least advanced, and grade 5 being most advanced. The spondylolisthesis is graded by measuring how much of a vertebral body has slipped forward over the body beneath it.

Grade 1 25% of vertebral body has slipped forward Grade 2 50% Grade 3 75% Grade 4 100% Grade 5 Vertebral body completely fallen off (i.e.,spondyloptosis)

Approximately 5-6% of males, and 2-3% of females have a spondylolisthesis. It becomes apparent more often in people who are involved with very physical activities such as weightlifting, gymnastics, or football. Males are more likely than females to develop symptoms from the disorder, primarily due to their engaging in more physical activities. Although some children under the age of five may be pre-disposed towards having a spondylolisthesis, or may indeed already have an undetected spondylolisthesis, it is rare that such young children are diagnosed with spondylolisthesis. Spondylolisthesis becomes more common among 7-10 year olds. The increased physical activities of adolescence and adulthood, along with the wear- and-tear of daily life, result in spondylolisthesis being most common among adolescents and adults.