What is the recommended management for hyperkyphosis (excessive outward curve of the thoracic spine) after failed thoracic fusion, particularly in relation to degenerative disk and vertebral body changes?

Management of Hyperkyphosis After Failed Thoracic Fusion

Revision surgery with extension of fusion to the sagittal stable vertebra (SSV) is recommended for hyperkyphosis after failed thoracic fusion, particularly when associated with degenerative disk and vertebral body changes. 1, 2

Understanding Post-Fusion Hyperkyphosis

Hyperkyphosis following thoracic fusion failure is a complex condition that can significantly impact patient morbidity, mortality, and quality of life. The causes are multifactorial:

• Degenerative changes in discs and vertebral bodies contribute to progressive kyphosis, especially in the aging population 3
• Failed fusion (pseudarthrosis) can lead to instrumentation failure and progressive deformity 4
• Improper selection of fusion levels during the initial surgery, particularly inadequate distal fusion level 1

Diagnostic Evaluation

• Radiographic assessment should include:

  • Standing full-spine radiographs to evaluate sagittal balance 1
  • Assessment of degenerative disc and vertebral body changes 3
  • Identification of the sagittal stable vertebra (SSV) - the most proximal lumbar vertebra touched by a vertical line from the posterior-superior corner of the sacrum 1
  • Evaluation of the first lordotic vertebra (FLV) - the vertebra just caudal to the first lordotic disc 1

• Clinical evaluation should focus on:

  • Pain severity and location 3
  • Neurological symptoms 4
  • Functional limitations and disability 3

Management Recommendations

Surgical Management

When revision surgery is indicated due to significant pain, disability, or progressive deformity:

• Extension of fusion to include the sagittal stable vertebra (SSV) is crucial 1, 2

  • Studies show significantly lower rates of distal junctional kyphosis (DJK) when fusion extends to the SSV (8%) compared to when it does not (71%) 1
  • Fusion to the SSV is superior to fusion to the first lordotic vertebra (FLV) for preventing DJK (13% vs 38% DJK rates) 2

• Surgical technique considerations:

  • Posterior spinal fusion with closing wedge osteotomies and hybrid instrumentation can achieve satisfactory correction 5
  • Careful attention to sagittal balance is essential 1
  • Bone grafting to promote solid fusion is recommended 5

Common Pitfalls to Avoid

• Stopping fusion short of the SSV - this is associated with a high rate (71%) of distal junctional problems 1
• Relying solely on the first lordotic vertebra (FLV) as the distal fusion level - DJK can still develop in 38% of cases despite extending to the FLV 2
• Failing to address sagittal balance - negative sagittal balance can contribute to adjacent segment problems 1

Outcomes

With appropriate surgical management:

• Significant correction of kyphosis can be achieved (mean correction of 39% in one study) 1
• SRS-22 scores can improve from a mean of 3.6 to 4.6, indicating substantial improvement in quality of life 5
• Complication rates can be minimized (12.5% in one study with proper technique) 5

Special Considerations

• Elderly patients with isolated hyperkyphosis are rarely treated surgically due to associated risks 3
• Non-operative management may be considered for mild cases or high-surgical-risk patients, though it typically only slows progression rather than correcting deformity 3
• Smoking status affects outcomes - non-smokers show greater improvement in quality of life following surgical correction 5