Adult Spinal Deformity

Adult Scoliosis

Definition

  • Scoliosis (>10-degree curve) diagnosed after skeletal maturity
  • Mean age: 60 years
  • Men = Women

Aetiology

  1. Idiopathic: Remnant of undiagnosed AIS (Adolescent Idiopathic Scoliosis)
  2. De Novo:
    • Degenerative (most common)
    • Pathologic
    • Traumatic
    • Iatrogenic
    • Neuromuscular

Classification

Idiopathic Adult Scoliosis

  • Based on location of curve & degree of sagittal & coronal imbalance

Degenerative Scoliosis

  • Type 1: No rotational element
  • Type 2: Rotational element
  • Type 3: Sagittal or coronal plane imbalance (plumb line)
    • Each has a subtype +/- neurologic symptoms

Clinical Presentation

  • Back pain is more common in adults with scoliosis
    • Not usually severe
  • Neurologic symptoms not common but can occur:
    • Stenosis (concavity of curve)
    • Radiculopathy
  • Cosmetic deformity
  • Cardiopulmonary problems (thoracic curves >70 degrees)
    • Mortality possible with curves >90 degrees

Curve Patterns

  • Idiopathic – remnant of AIS:
    • Right Thoracic most common
  • De-Novo (degenerative):
    • Lumbar/Thoracolumbar curves:
      • Lower magnitude
      • Fewer levels involved
      • No real pattern

Progression of Curve

  • 1 degree per year for thoracic curves >50 degrees
  • 0.5 degrees per year for thoracolumbar curves
  • 0.25 degrees per year for lumbar curves

Risk Factors for Progression

  • Curves >30 degrees
  • Younger patients
  • Right thoracic curves

Diagnosis

History

  • Pain – does it correlate to scoliosis?
  • Neurologic symptoms
  • Curve progression
  • Functional impairment

Examination

  • Neurology
  • Forward & side bending – do curves correct?
  • Which are structural/compensatory?

X-Rays

  • 36-inch cassette XR AP & lateral
  • Plumb line to assess sagittal & coronal balance:
    • Should pass just anterior to sacrum from C7
  • Forward and Side bending views
  • Structural and compensatory curves (primary & secondary)
  • Are curves flexible? i.e., do they need release before correction?

Lieberman J (2009) AAOS Comprehensive Review

  • Sagittal plane plumb line should be 1-2cm anterior to anterior sacrum:
    • Increase = positive balance, decrease = negative balance
  • Coronal plane balance should be within 2cm of centre of sacrum

MRI

  • Assess neural structures

Management

  • Mainstay is non-surgical:
    • Physiotherapy, education, analgesia & activity modification

Surgical

  • Indications:
    • Intractable pain
    • Neurologic deficit
    • Cardiopulmonary compromise
    • Significant gait disturbance
    • Cosmesis (relative)
    • Curve >50 degrees in younger patients – more time to progress
    • Curve >70 degrees in older patients

Goals

  • Pain relief
  • Solid fusion
  • Spinal balance

Techniques

  • Posterior instrumented fusion between normal vertebrae
    • In thoracic curves, better to sacrifice proximal levels and spare distal levels
    • Don’t stop fusion at thoracolumbar junction – leads to kyphosis
  • Consider 2-stage surgery if curves rigid
  • Consider anterior supplementation for large curves (>70 degrees)
2-Stage Surgery +/- Supplementary Anterior Fusion
  • For large curves (>70 degrees)
  • Rigid curves as demonstrated by side bending X-rays
  • Lumbar curves
  • Anterior fusion only is possible for milder thoracolumbar curves:
    • Reduces the number of levels to fuse – stop at neutral rather than horizontal vertebra
Fusion to Sacrum
  • Necessary in large lumbar deformities
  • Associated spondylolisthesis at L5/S1
  • Rigid curve requiring anterior lumbar release
  • Problems:
    • Higher pseudoarthrosis rate
    • Pain
    • Instrumentation failure
    • Loss of lordosis
Sacropelvic Fusion
  • With iliac screws
  • Consider if sacrum included in a long fusion
  • Stabilises sacrum further
Osteotomy
  • For rigid kyphotic deformity
  • Pedicle subtraction or Smith-Peterson anterior opening wedge
  • Higher complication rate

Overall Complications

  • Higher in older patients, patients where sacrum included & larger curves
  • Pseudoarthrosis (most common: 5-20%):
    • Occurs most at junctional levels (T12/L1 & L5/S1)
  • Infection
  • Bleeding
  • UTI
  • Metalware failure
  • Neurologic compromise (1-5%)

Kyphosis

Aetiology

  • Most often thoracic spine but may occur anywhere, especially at junctional levels
  • Idiopathic, Post-traumatic, Osteoporotic

Idiopathic

  • Residual Scheuermann’s or congenital kyphosis
  • Management:
    • Surgical if non-operative treatment fails & symptoms severe
    • Posterior instrumented fusion of whole kyphotic segment
    • Anterior release and fusion if stiff curve:
      • Does not correct to at least 55 degrees on extension XR

Post-Traumatic

  • Post-fracture Rx non-operatively
  • Post-instrumentation with failed fusion
  • Post-laminectomy without fusion:
    • Can cause pain & instability
    • Progressive kyphosis may occur
    • Posterior corrective fusion with instrumentation
    • Add anterior decompression if neurologic compromise

Osteoporotic

  • Single or multiple wedge compression fractures
  • Can be treated in the same way as above if very symptomatic
  • But due to osteoporosis, failure is much higher
  • Complications all higher
  • Kyphoplasty & Vertebroplasty:
    • Good and equal short-term pain relief
    • Kyphoplasty meant to correct deformity as well
    • Long-term results not proven

Corrective Osteotomy

  • An option for rigid & severe deformities (>70 degrees)

Pedicle Subtraction Osteotomy

  • 3-column osteotomy
  • Up to 30-degree correction per level
  • More neurologic risk
  • Therefore preferred below conus where cord has ended

Anterior Opening Wedge Smith-Peterson Osteotomy

  • Osteotomy through posterior column only – more traditional method
  • Up to 10-degree correction per level
  • Complications with all osteotomies are higher, especially in:
    • Older patients
    • Multiple co-morbidities
    • Poor nutrition
    • Osteoporosis
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