Spine structured oral questions6: Spondylolisthesis

EXAMINER: What is this? (Figure 5.8.)

CANDIDATE: I can see T2-weighted sagittal and coronal MRI images showing the lumbar spine and there is a spondylolisthesis at L5/S1.

EXAMINER : What grade is it and what types of spondylolisthesis do you know?

CANDIDATE: Spondylolisthesis is graded according to Meyerding’s grading system which is graded I–IV according to how far from posterior to anterior the more cranial vertebral

Figure 5.8

T2-weighted MRI sagittal demonstrating L5/S1 spondylolisthesis.

body has slipped forward. Grade I is less than a ¼ (25%), grade II is ¼ – ½ (25–50%), grade III is ½ – ³₄ (50–75%) and grade IV is > ³₄ (>75%). A spondyloptysis is a slip greater than 100% where the more cranial vertebral body lies anterior to the more caudal one (grade V).

 

Five different types of spondylolisthesis were described by Wiltze

1. Dysplastic – Congenital abnormalities of the sacrum or L5 allow the slip to occur.

2. Isthmic – Here the defect is in the pars and it is subdivided into a lytic failure, an acute fracture, or an elongated but intact pars.

3. Degenerative – This is due to degenerative change that produces intersegmental instability (due to changes in disc, joint capsules and facet joints).

IV.Traumatic – Due to a fracture (but not of the pars,

e.g. pedicle).

IV.Pathological – Caused by local bone disease (disease may not be localized).

Spondylolisthesis background knowledge

Note: When considering an isthmic (spondylolytic) spondylolysis the ‘step’ in the spinous processes posteriorly the step in the posterior elements will occur one level above that of the pars defect. The posterior element step is at L4/5 in an L5 spondylolysis (the spondylolisthesis being at L5/S1).

In children spondylolytic (isthmic) spondylolisthesis at the L5/S1 junction is more common. Approximately 50% of spondylolyses have a spondylolysis without the associated slip. It is twice as common in men as in women. Typically it first occurs during or just before adolescence and may progress until skeletal maturity. There is a genetic component with between one-third and two-thirds having a family member affected. It may also be associated with spina bidifa (up to 40%). The main symptoms are usually a dull aching pain in the low back and buttocks exacerbated by activity; this may be associated with an L5 radiculopathy. Many are asymptomatic. Of symptomatic children the majority (90%) also become symptomatic again in adult life. Hamstring shortening is a common finding on examination. In high grade slips adolescents may present with a ‘spondylolytic crisis’ in which pain, neurological compromise and the Phalen–Dickson sign of flexed hips and knees and a waddling gait when walking may all be present.

Conservative management (activity modification, +/ bracing) may allow healing of the pars defect. Core stability exercises, hamstring stretching and bracing all have a role. Surgical stabilization may be considered if conservative management fails or a progressive slip is identified. Patients should be followed up until skeletal maturity after which it is unlikely that the slip will progress.

Degenerative spondylolisthesis most commonly occurs at the L4/L5 level and is frequently associated with stenosis at that level. There is an intact neural arch and the slip is caused by instability of the motion segment, in turn caused by dehydration of the disc and loss of disc height as well as facet joint degeneration. This type is five times more common in women than in men. Symptoms may be of back pain radiating into the thighs, radicular symptoms (50%), or symptoms of neurogenic claudication.