How Safe Is Unilateral Pedicle Screw Fixation in Lumbar Fusion Surgery for Management of 2-Level Lumbar Degenerative Disorders Compared with Bilateral Pedicle Screw Fixation? Meta-analysis of Randomized Controlled Trials

World Neurosurg. 2020 Aug;140:357-368. doi: 10.1016/j.wneu.2020.05.078. Epub 2020 May 16.


Objective: We performed this meta-analysis to compare the safety of unilateral with bilateral instrumented fusion in 2-level degenerative disorders of the lumbar spine.

Methods: We conducted an independent and a duplicate electronic database search including PubMed, Embase, and Cochrane Library until January 2020 for randomized controlled trials (RCTs) comparing unilateral pedicle screw fixation with bilateral pedicle screw fixation for multilevel lumbar degenerative disorders. Fusion and complication rates were the primary outcomes analyzed. Analysis was performed in R platform using OpenMeta[Analyst] software.

Results: Five RCTs including 215 patients (Unilateral/Bilateral = 106/109) were included in the meta-analysis. There was no significant difference between the 2 groups regarding fusion rate, complication rate, blood loss, duration of hospital stay, functional outcome scores like Visual Analog Scale, Oswestry Disability Index, and Short-Form 36 health survey at the final follow-up. Unilateral pedicle screw fixation was associated with a significant reduction in operation time (P < 0.001). Compared with the open approach, the minimally invasive approach showed a significant difference in terms of factors like operative time, blood loss, hospital stay, Visual Analog Scale, and Oswestry Disability Index (P = 0.004).

Conclusions: Our meta-analysis establishes the immediate safety and significant lesser operative period of unilateral pedicle screw fixation in lumbar fusion. However, due to lack of evidence on complications like cage subsidence and adjacent segment disease, unilateral pedicle screw fixation cannot be recommended as an alternative to bilateral pedicle screw fixation for 2-level degenerative spinal disease. Our analysis established the lacunae in literature for high-quality evidence on the subject; hence we recommend further large multicenter studies with longer follow-up to arrive at a conclusion.

Publication types

  • Meta-Analysis
  • Review

MeSH terms

  • Humans
  • Intervertebral Disc Degeneration / surgery*
  • Lumbar Vertebrae / surgery*
  • Pedicle Screws / adverse effects*
  • Randomized Controlled Trials as Topic
  • Spinal Fusion / adverse effects
  • Spinal Fusion / methods*
  • Treatment Outcome