Neurosurgery notes/Procedures/TL spine procedures/Deformity techniques/Spinal release

Spinal release

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Deformity techniques

General

  • Spinal release techniques are employed to increase the flexibility of the vertebral column
  • Can be done either posterior or anterior approaches.

Posterior-Based Osteotomies

  • Purpose: Improve spinal mobility and facilitate deformity correction in Adolescent Idiopathic Scoliosis (AIS).
  • Facetectomies: Routinely performed to increase segmental flexibility, for example, in the convex pedicle screw technique.

Anterior Release

  • Purpose:
    • To increase spinal mobility
  • Current Relevance:
    • Valuable option for severe, rigid curves or deformities with significant thoracic lordosis (>10°).
      • Its popularity declined with pedicle screw instrumentation
      • Historically used for large, stiff curves or thoracic hypokyphosis.
  • Approach:
    • Open approach
      • Carries risks of pulmonary function impairment due to chest wall disruption.
    • Thoracoscopic approaches
      • Carries risks of pulmonary function impairment due to chest wall disruption.
      • Thoracoscopic release in the prone position offers similar safety and efficacy to the lateral position
        • Avoids single-lung ventilation and patient repositioning, with no adverse effect on pulmonary function.
  • Impact on Pulmonary Function:
    • Anterior release + posterior spinal instrumentation and fusion (PSIF) results in moderate pulmonary function improvement at two years postoperatively.
    • Anterior spinal fusion (ASF) causes a temporary decline in pulmonary function, which normalises to preoperative levels within two years.
    • Combined anterior and posterior spinal fusion (A/PSF) has shown no long-term pulmonary decline and significant improvement in quality of life with high patient satisfaction.
  • Advantages:
    • Allows performing an anterior thoracoplasty to improve the cosmetic aspect of convex rib prominence by excising rib heads, creating a "flail" convex hemithorax that heals in an improved position.
    • Circumferential 360° fusion (Anterior spinal release + posterior fusion)
      • Prevents the risk of crankshaft effect in younger patients due to remaining anterior vertebral body growth.
      • However, modern segmental pedicle screw constructs may also prevent this phenomenon.
  • Disadvantages:
    • Necessitates ligation of segmental vessels,
      • which can potentially lead to permanent neurological compromise (reported risk rates ranging from 0% to 0.86%).
      • Unilateral segmental vessel ligation is generally considered safe, except in cases involving complex congenital spinal deformities with associated vascular abnormalities.
  • Efficacy:
    • Clinical evidence does not consistently support its role in restoring thoracic kyphosis.
    • Studies have found no significant difference in thoracic kyphosis restoration or coronal/sagittal plane correction compared to posterior-only approaches.
    • Its indications should be carefully considered given the lack of consistent evidence for superiority over posterior-only approaches.