Abstract

The term spondylolisthesis defines a condition in which the vertebral bodies slip forward in relation to the vertebrae beneath. Most commonly L5 slips over S1. The disease affects approx. 6–9% of the population. The condition most commonly occurs in children, adolescents, and in individuals > 50 years old. Risk factors are repetitive hyperextension of the spine (e.g., gymnastics), trauma, bone pathologies, or degenerative spine disease. Spondylolisthesis may be asymptomatic or cause lumbar pain on exertion, gait problems, radiculopathic pain, or urinary incontinence. In some patients a step-off at the lumbosacral area is palpable. Diagnosis is established through imaging. Most patients achieve good results with conservative treatment (e.g., physical therapy). Surgical treatment (e.g, vertebral fusion, decompression of the nerves) is reserved for patients with refractory cases and neurologic deficits. Overall, children and adolescents achieve better results than adults and elderly.

Epidemiology

Affects up to 10% of the population
Most common in children < 6 years, 12–17 years (congenital and spondylolytic form) and adults aged > 50 years (degenerative form)
Sex: ♂ > ♀ (congenital and spondylolytic form); ♀ > ♂ (degenerative form)
Defect most commonly occurs in the lumbar spine (L5 in 80% of cases), L4 in 15% of cases

References:^[1]^[2]^[3]^[4]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

Risk factors:
- Congenital malformation (dysplasia or hypoplasia) of the lumbosacral joints in L5–S1
- Repetitive hyperextension and rotation movements at L5–S1
  - Commonly associated with gymnastics, swimming, and weight lifting
- Spondylolysis: lytic defect in the pars interarticularis, permitting forward slippage of the superior vertebra
- Degenerative disease: most commonly in the elderly at L4–L5
- Trauma
- Local or systemic pathology (e.g., tumor, Paget's disease, osteogenesis imperfecta, Tbc)

References:^[1]

Clinical features

Asymptomatic (∼ 90% of cases)
Chronic lumbar pain that worsens with exertion and/or when reclining
Gait problems (e.g., waddling gait)
Possibly urinary or bowel incontinence

References:^[1]

Diagnostics

Physical examination
- Step-off sign: In advanced stages, a noticeable step-off at the lumbosacral area may be palpated or even seen when the patient is standing.
- Straight leg raise test: A straight leg raise with the patient lying on the back causes pain and therefore triggers elevation of the entire trunk (to relieve the pain).
- Tight, contracted hamstring muscles
- Possible weakness and atrophy in lower legs; reduced sensation and reflexes

Provocative test: The relief from pain after local injection of lidocaine at the level of the pars interarticularis may help confirm the diagnosis.

Radiologic examination:
- Conventional x-ray of lumbosacral spine
  - Indication: to evaluate the vertebral structures, the degree and severity of forward slippage, the slip angle, and the presence of concomitant spine pathologies
  - Usually spondylolisthesis is an incidental finding.
  - Specific signs:
    - Scotty dog with a collar sign in spondylolysis: normal appearance of the lumbar spine in an oblique projection at 45° is referred to as "Scotty dog sign" → in spondylolysis, the fracture line appears as the "dog's collar"
CT scan: used to rule out other causes of pain (e.g., tumor), in traumatic cases, and to guide surgical treatment.
MRI: helps visualize the compression of the nerve roots

SPECT (Single-photon emission computed tomography): useful in detecting stress injuries or defects, their progression and healing potential, guiding the treatment

References:^[5]

Differential diagnoses

Ankylosing spondylitis
Multiple myeloma
Spinal disc herniation
Metastatic bone disease
Scheuermann's disease
Facet joint syndrome
- Irritation of the facet joints, usually due to spondyloarthritis

The differential diagnoses listed here are not exhaustive.

Treatment

The main goals in the treatment of spondylolisthesis are to reduce pain, restore the mobility of the spine, and prevent further disease progression.

Conservative treatment
- Indication: patients with low-grade spondylolisthesis (< 50% slippage of cranial vertebra over the caudal vertebra) and degenerative spondylolisthesis with no neurological deficits
- Physical therapy emphasizing training of back and abdominal muscles
- Activity modification: avoid sports which contribute to spondylolisthesis
- Orthotic braces
Surgical treatment
- Indication: high-grade spondylolisthesis (> 50% slippage of cranial vertebra over the caudal vertebra), neurologic deficits, traumatic spondylolisthesis or if symptoms progress despite conservative treatment
- Standard procedure: vertebral fusion
- Nerve decompression in the case of radiculopathic pain or bowel/bladder dysfunction

References:^[5]^[1]

Prognosis

Conservative treatment gives satisfactory results in 80% of cases.
The rate of success from surgical treatment is higher in children than in adults.

References:^[6]^[7]^[8]^[9]