title: Feasibility and accuracy of new insertion technique of S1 transpedicular screw. Computed tomography-based morphometric analysis.
abstract: OBJECTIVE
  To assess feasibility and accuracy of a new insertion technique of S1 transpedicular screw.
  
  
  BACKGROUND
  Transpedicular stabilization in the first sacral vertebra (S1) is a technically demanding surgical procedure with inherent risk of loosening of the implant. A modification of the technique was recently proposed, along with the analytical verification which was performed based on the available literature. In the study, we performed radiological assessment of screws inserted into the S1 using the classical and modified techniques.
  
  
  METHODS
  The analysis was performed in two parts. The first part was performed on eight cadaver specimens after implantation of the screws. In the second part, we used computed tomography images of patients with degenerative disk disease with a superimposed representation of screws. The thickness of the posterior cortex adherent to the screws, screw trajectory and their position with regard to the spinal canal was measured. The area of posterior cortex in contact with the screws was also calculated.
  
  
  RESULTS
  The contact length and area was found to be two times greater for screws introduced with the modified technique. The convergence angle was comparable between the techniques, despite the shift of entry point. There was no canal breach, although with the modified technique the screws passed closer to the spinal canal.
  
  
  CONCLUSIONS
  The modified technique is considered safe. In this technique, the screws pass through a thicker portion of the posterior cortex compared to the classical technique that aims at improving the stability of the fixation.
authors: Department of Orthopedic and Traumatology, W. Dega University Hospital, Poznań, Poland.
authors: Łukasz
authors: Ł
authors: Kubaszewski
authors: Department of Neurosurgery, Specialist Medical Center, Polanica-Zdrój, Poland. Electronic address: gmiekisiak@gmail.com.
authors: Grzegorz
authors: G
authors: Miękisiak
authors: Department of Spine Surgery, Oncology, Orthopedics and Traumatology, W. Dega University Hospital, Poznań, Poland.
authors: Andrzej
authors: A
authors: Nowakowski
authors: Faculty of Mechanical Engineering, Wroclaw University of Technology, Wrocław, Poland.
authors: Celina
authors: C
authors: Pezowicz
authors: Department of Human Anatomy, Medical University of Silesia, Katowice, Poland.
authors: Grzegorz
authors: G
authors: Bajor
authors: Wrocław University of Environmental and Life Sciences, The Faculty of Veterinary Medicine, Wroclaw, Poland.
authors: Zdzisław
authors: Z
authors: Kiełbowicz
authors: Wrocław University of Environmental and Life Sciences, The Faculty of Veterinary Medicine, Wroclaw, Poland.
authors: Wojciech
authors: W
authors: Kinda
authors: Faculty of Mechanical Engineering, Wroclaw University of Technology, Wrocław, Poland.
authors: Magdalena
authors: M
authors: Wojtków
authors: Department of Orthopedic and Traumatology, W. Dega University Hospital, Poznań, Poland.
authors: Jacek
authors: J
authors: Kaczmarczyk
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D002102:Cadaver; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007593:Joint Instability / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D019635:Neurosurgical Procedures / Q000379:methods*; D019637:Orthopedic Procedures / Q000379:methods*; D019651:Plastic Surgery Procedures; D013115:Spinal Canal / Q000000981:diagnostic imaging / Q000601:surgery; D013123:Spinal Fusion / Q000379:methods; D014057:Tomography, X-Ray Computed
keywords: Anatomy; Entry point; Pedicle screw; Sacrum