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