What are potential complications of spinal fusion?

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Last updated: October 8, 2025 • View editorial policy

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Complications of Spinal Fusion

Spinal fusion surgery can lead to several significant complications including pseudarthrosis (failed fusion), adjacent segment disease, hardware failure, infection, and neurological deficits, all of which may require revision surgery and significantly impact patient morbidity and mortality. 1, 2

Major Complications

Pseudarthrosis

  • Pseudarthrosis (failed fusion) is one of the most common complications of spinal fusion, occurring in up to 56% of patients 1
  • Risk factors include:
    • Patient factors: age, smoking status, diabetes, hypoalbuminemia 1
    • Surgical factors: number of levels fused, surgical approach/technique, type of bone graft 1, 2
  • Diagnosis typically requires CT imaging, which is considered the most sensitive and specific modality for assessment of fusion status 1, 3
  • Even when asymptomatic, pseudarthrosis may lead to multiple readmissions or revision surgeries 1

Adjacent Segment Disease

  • Accelerated degeneration of spinal segments above or below the fusion site 1
  • Reported incidence of 3.1% for total disc replacement and reoperation rates of 22.2% at 10 years for anterior cervical arthrodesis 1
  • Can lead to new pain, neurological symptoms, and need for additional surgery to extend the fusion 2

Hardware Complications

  • Include screw loosening, pull-out, breakage, or migration 4
  • May result in instability, deformity, or neurological compromise 4
  • CT scans are the preferred imaging modality for detecting hardware complications 1
  • Often requires revision surgery with more extensive instrumentation 5

Infection

  • Surgical site infections (SSIs) occur in approximately 3-4.5% of spinal fusion cases 1
  • Risk factors include:
    • Low preoperative albumin and total protein levels 1
    • Thicker subcutaneous fat 1
    • Higher American Society of Anesthesiologists score 1
    • Longer postoperative wound drainage 1

Neurological Complications

  • Can range from radiculopathy to myelopathy or cauda equina syndrome 1
  • May result from direct neural injury, hardware migration, or hematoma formation 1
  • Reported in up to 2% of patients undergoing posterior fusion procedures 6

Approach-Specific Complications

Anterior Approach Complications

  • Dysphagia, hoarseness, and injury to adjacent structures (esophagus, trachea, vessels) 2, 5
  • Pseudarthrosis rate of approximately 2.6% for anterior cervical discectomy and fusion 1

Posterior Approach Complications

  • Higher risk of wound complications and infection 1
  • Potential for muscle denervation and chronic pain 1
  • Late deterioration reported in up to 29% of patients undergoing laminectomy 1

Combined Anterior-Posterior Approach

  • Higher complication rates due to increased surgical time and blood loss 6
  • May be necessary for complex cases with severe deformity or hardware failure 4

Management of Complications

Revision Surgery

  • Often required for symptomatic pseudarthrosis, hardware failure, or adjacent segment disease 2
  • May involve:
    • Replacing loose instrumentation 4
    • Extending the fusion construct 2
    • Adding more potent biologics to enhance fusion 7
    • Using interbody fusion techniques 7

Prevention Strategies

  • Preoperative optimization of modifiable risk factors (smoking cessation, nutritional status) 1, 2
  • Appropriate surgical technique and instrumentation selection 2
  • Use of bone graft extenders or substitutes in high-risk patients 1
  • Consideration of bone morphogenetic proteins (BMPs) in select cases, though these carry their own risks 1

Special Considerations

Elderly Patients

  • Higher risk of perioperative complications, especially in those over 65 years 6
  • Excessive intraoperative blood loss is a significant risk factor for early complications 6
  • Number of levels fused correlates with blood loss and complication risk 6

Nutritional Status

  • Hypoalbuminemia significantly increases risk of surgical site infections and pseudarthrosis 1
  • Preoperative albumin and bone turnover markers are independently predictive of nonunion 1
  • Preoperative nutritional assessment and optimization is recommended 1

By understanding these potential complications, surgeons can better counsel patients, optimize modifiable risk factors, and select appropriate surgical techniques to minimize adverse outcomes following spinal fusion.

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

4
Guideline

Medical Necessity of Combined Anterior-Posterior Approach for Hardware Failure in Cervical Spine

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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