Pars interarticularis screws for posterior cervical fusion - investigating a new trajectory using a CT-based multiplanar reconstruction: Part I

Sara Lener, Christoph Wipplinger, Anto Abramovic, Heiko Koller (Co-author), Claudius Thome, Michael Verius, Sebastian Hartmann

Research output: Contribution to journalOriginal Articlepeer-review

Abstract

Background Lateral mass screw fixation is the standard for posterior cervical fusion between C3 and C6. Traditional trajectories stabilize but carry risks, including nerve root and vertebral artery injuries. Minimally invasive spine surgery (MISS) is gaining popularity, but trajectories present anatomical challenges. Research Question. This study proposes a novel pars interarticularis screw trajectory to address these issues and enhance in-line instrumentation with cervical pedicle screws. Materials and Methods A retrospective analysis of reformatted cervical CT scans included 10 patients. Measurements of the pars interarticularis morphology were performed on 80 segments (C3-C6). Two pars interarticularis screw trajectories were evaluated: Trajectory A (upper outer quadrant entry, horizontal trajectory) and Trajectory B (lower outer quadrant entry, cranially pointed trajectory). These were compared to standard lateral mass and cervical pedicle screw trajectories, assessing screw lengths, angles, and potential risks to the spinal canal and transverse foramen. Results Trajectory B showed significantly longer pars lengths (15.69 +/- 0.65 mm) compared to Trajectory A (12.51 +/- 0.24 mm; p < 0.01). Lateral mass screw lengths were comparable to pars interarticularis screw lengths using Trajectory B. Both trajectories provided safe angular ranges, minimizing the risk to delicate structures. Discussionand Conclusion. Pars interarticularis screws offer a viable alternative to lateral mass screws for posterior cervical fusion, especially in MISS contexts. Trajectory B, in particular, presents a feasible and safe alternative, reducing the risk of vertebral artery and spinal cord injury. Preoperative assessment and intraoperative technologies are essential for successful implementation. Biomechanical validation is needed before clinical application.
Original languageEnglish
Article number295
Number of pages8
JournalACTA NEUROCHIRURGICA
Volume166
Issue number1
DOIs
Publication statusPublished - 11 Jul 2024

Keywords

  • Dorsal cervical fusion
  • Dorsal cervical stabilization
  • Isthmus
  • Novel trajectory
  • Pars interarticularis

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