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Spondylolisthesis and Spondylolysis N039

Last amended 
13 March 2017
Current RMA Instruments
Reasonable Hypothesis SOP
24 of 2017
Balance of Probabilities SOP
25 of 2017
Changes from previous Instruments

Bulletin 195.pdf

ICD Coding:
  • ICD-9-CM: 738.4, 756.11, 756.12
  • ICD-10-AM: M43.0, M43.1, Q76.21, Q76.22
Brief description:    

The SOP covers:

  • Spondylolysis, which is a fracture or defect of a specific part of a vertebra (the pars interarticularis).
  • Spondylolisthesis, which is displacement of one vertebra relative to the one below.  Spondylolisthesis is most commonly a forward displacement of a vertebra relative to the one below (anterolisthesis), but uncommonly, there may be backward displacement of a vertebra relative to the one below (retrolisthesis).

Spondylolisthesis is mostly secondary to spondylolysis, but can also be due to spondylosis and some other causes.

Spondylolysis occurs at the L5 level of the lumbar spine in around 90% of cases, with the remainder almost all at L4.

Confirming the diagnosis

Diagnosis requires X-ray, CT scan or MRI scan showing a pars interarticularis fracture or displacement of one vetebra relative to the one below.

The specific type of the condition (see further comments below) needs to be known to apply some of the SOPs factors.  This will be evident from the imaging.

The relevant specialist is an orthopaedic surgeon.

Additional diagnoses covered by SOP
  • Anterolisthesis
  • Retrolisthesis
  • Degenerative spondylolisthesis
Conditions not covered by these SOPs
  • Spondylosis*

* another SOP applies

Further comments on diagnosis


  • Spondylolysis - pars interarticularis fracture (usually bilateral), without vertebral displacement.  The pars interarticularis is a segment of bone on the vertebral arch at the back of the vertebra which connects the superior articular facet to the inferior articular facet. It is best seen on oblique X-ray views as the collar on the ‘scottie dog’ image. This condition is either developmental – normally occurring in childhood at around 8 yrs of age, or a stress (overuse) fracture in child and adolescent athletes.
  • Spondylolytic spondylolisthesis - forward displacement of vertebra + bilateral pars interarticularis fracture. 
  • Degenerative spondylolisthesis -  displacement of vertebra associated with degeneration of facet joints and the absence of pars interarticularis fracture/s.  This occurs later in life and typically where there is advanced degenerative disease of the facet joints.
  • Spondylolisthesis may also rarely arise due to congenital dysplasia of the vertebrae, following severe, high impact trauma, or from bone pathology such as from osteomyelitis or an invasive neoplasm.
  • Retrolisthesis usually affects the cervical spine or the lumbar spine, most commonly in the setting of degenerative changes (spondylosis).
Clinical onset

The condition may be asymptomatic and found incidentally on X-ray.  This is particularly the case when it develops in early life.  In adolescent athletes onset is usually gradual, in the form of low back pain with activity.  It is not usually associated with an acute event.  Spondylolysis or spondylolytic spondylolisthesis is unlikely to be the cause of new onset back pain in an adult (especially if ≥ 25 yrs).  Degenerative spondylolisthesis and retrolisthesis usually manifest later in life in the setting of advanced degenerative disease.

Clinical worsening

Documented progression from spondylolysis to spondylolisthesis or an increase in the degree of slipping would represent a clinical worsening.