Degenerative Lumbar Scoliosis

Aetiology

  • Typically develops after age 50 years
  • Factors implicated in development of degenerative scoliosis:
    • Osteoporosis
    • Degenerative disc disease
    • Osteoarthritis
    • Stenosis
    • Endochondral abnormalities
    • Compression fractures
    • Facet tropism
    • Lateral listhesis
  • Essentially 2 pathophysiologic processes result in scoliotic deformity:
    • Isolated degenerative arthritis of posterior facet joints to point of incompetence, when anterolisthesis develops
    • Asymmetric collapse of disc & asymmetric incompetence & hypertrophy of facet joints, leading to a lateral & rotational deformity; result is deformity combined with varying degrees of central lateral recess & foraminal stenosis

Natural History

  • Characterised by minimal structural vertebral deformities, advanced degenerative changes, & a predominance of lower lumbar curves
  • Distinguished from adult idiopathic scoliosis by radiographic confirmation of a straight spine during adulthood with subsequent development of a degenerative curve
  • Unilateral radicular symptoms much more common on side of concavity of deformity
  • Risk factors for curve progression:

Degenerative Lumbar Scoliosis 1

 

Imaging

  • Plain radiographs:
    • Patient standing without bending at knees or hips, using full-spine films to assess overall spinal balance (including EOS imaging)
    • Evaluated for
      • Curve location
      • Number of levels involved
      • Direction of curve
      • Magnitude of curve
      • Risk factors for progression
        • Lateral listhesis
        • Apical rotation
        • Height of residual disk spaces throughout deformity
        • Spondylolisthesis
        • Osteoporotic compression fractures
  • MRI:
    • Spinal stenosis

Management

  • Non-operative:
    • Physiotherapy
      • Aerobic exercise to improve cardiovascular reserve while decreasing pain & increasing function
      • Trunk stabilisation
    • NSAIDs
    • Paracetamol-based analgesic
    • Pain unit consultation
      • §  Tricyclic antidepressants
        • Night pain & can decrease neurogenic pain
      • §  Gabapentin/Pregabalin
        • May help in decreasing neurogenic pain
      • §  Narcotic medications
    • Spinal orthoses
      • Used primarily to control symptoms & do not stop progression of curve
      • Potential for pain relief must be balanced with discomfort of wearing a brace & potential for trunk muscle deconditioning
      • If a patient is able to function better with a brace than without, its use may be justified
      • Patients who use a brace should exercise regularly to avoid further deconditioning
      • Choice of orthosis should be based on perceived goal
        • Rigid lumbosacral orthosis may provide reasonable function for some patients with degenerative scoliosis
        • Rigid thoracolumbosacral orthosis typically would be used to help rib-to-pelvis impingement
    • Transcutaneous electrical nerve stimulation (TENS)
    • Epidural steroids, facet blocks, nerve-root blocks
      • Useful for diagnostic purposes in addition to their short-term therapeutic benefit
  • Operative:
    • Indications
      • Severe, refractory pain limiting ADL’s
      • Progressive deformity
      • Progressive neurologic deficits
      • Spinal imbalance
    • Decompression
    • Decompression & fusion
      • Most patients should be treated with decompression & fusion with bilateral fixation devices
      • Decompression alone could lead to further collapse, instability, & increased lower back & nerve pain
      • 85% good to excellent results in terms of little to no lower extremity pain post-operatively

Surgical Recommendations

  • Decompression with or without fusion:
    • Most surgical candidates present with symptoms of neurogenic claudication, which necessitates decompression
    • If epidural injections provide temporary pain relief, & disc spaces through deformity are severely collapsed with no lateral listhesis or anterolisthesis, decompression alone or decompression with posterior spinal fusion without fixation devices can be considered
    • If more evidence of spinal instability is present, need for arthrodesis is clearer
  • Decompression & instrumented fusion:
    • In a patient with lateral listhesis >5mm, anterolisthesis, or residual disc space height with degenerative scoliosis, posterior fusion with instrumentation is reasonable
    • Technique also should be considered when substantial back pain accompanies neurogenic claudication
    • If no coronal or sagittal imbalance, fusion can be limited to levels decompressed
    • Fusion to sacrum is rarely indicated
      • If clinically significant stenosis involves L5-S1 level, a laminectomy of L5 can be done with a fusion to L5
      • If clinically significant spinal stenosis as well as a deformity, such as spondylolisthesis or severe foraminal stenosis at L5-S1 level, then fusion of L5 with S1 is indicated
      • Interbody fusion at L5-S1 level should also be considered, either through a posterior or separate anterior procedure, to structurally augment L5-S1 level & speed fusion
  • Deformity reconstruction:
    • Observation warranted with isolated or progressive deformity with minimal pain & well-maintained spinal balance
    • With mechanical back pain +/- neurogenic claudication, deformity is usually one of sagittal imbalance with a lumbar flat back, but it also may include elements of coronal imbalance
      • Decompression alone in this situation has a very high failure rate
      • Surgical plan should assure spinal balance &, in most cases, will require fusion to the sacrum
      • If deformity involves L5-S1 level, reconstruction must incorporate this level to assure spinal balance
      • Reconstructions often require either combined anterior & posterior approaches, multilevel posterior interbody procedures, or posterior osteotomies with fixation devices
  • Complications:
    • Occur in 20 to 40% & include
      • Pseudarthrosis
      • Wound infection
      • Paresthesias
      • Radiculopathy
      • CSF fistulas
      • Hardware failure
      • Compression fractures
      • Urinary tract infection
      • DVT / PE
      • Myocardial infarction
      • Adult respiratory distress syndrome
    • When junctional stenosis, degenerative disc disease, & progressive kyphosis proximal to fusion occur, extending proximal fusion in upper thoracic spine is justified
      • Fusion done 1 to 2 levels proximal to decompressed segments may ease transition to normal spine