Failure of monoaxial pedicle screws at the distal end of scoliosis constructs: A case series

Pramod B. Voleti, Francis H. Shen, Vincent Arlet

Research output: Contribution to journalArticle

3 Scopus citations


Background The goals of instrumented fusion for scoliosis are to correct deformities, stabilize the spine, and achieve arthrodesis. Monoaxial pedicle screws are often used in scoliosis constructs and have shown superiority over other types of pedicle screws in their ability to correct vertebral rotation and lumbar lordosis. However, because of the fixed-angle nature of the monoaxial pedicle screw head, any malalignment at the rod-screw interface could result in less than optimum stability. Results This series exhibits 3 cases of set screw loosening with the use of monoaxial pedicle screws at the distal end of long spinal fusion constructs for the management of patients with scoliosis; these complications all occurred within 6 months of the index procedures. The results of a detailed microscopic analysis of the failed components from 1 of the cases are also presented. Conclusions From this evidence, the authors of the current study recommend that surgeons exercise caution when using monoaxial pedicle screws at the distal end of long spinal fusion constructs, especially after compression has been achieved on the convex portion of the curve.

Original languageEnglish (US)
Pages (from-to)110-121
Number of pages12
JournalSpine deformity
Issue number2
Publication statusPublished - Mar 2014
Externally publishedYes



  • Idiopathic scoliosis
  • Monoaxial pedicle screws
  • Posterior spinal fusion
  • Set screw loosening

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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