title: Accuracy of the Free-hand Placement of Pedicle Screws in the Lumbosacral Spine Using a Universal Entry Point: Clinical Validation.
abstract: METHODS
  Retrospective radiographic study.
  
  
  OBJECTIVE
  To evaluate the accuracy of the free-hand placement of pedicle screws (PSs) using a new method of localization of entry points.
  
  
  BACKGROUND
  The PSs are essential in modern spinal surgery but their placement can be technically demanding. To improve this accuracy, numerous aids have been developed, some of them technologically advanced. Despite advances in technology the free-hand technique is still very popular. A simple geometric method of localization of entry points is proposed, designed to improved anatomic orientation.
  
  
  METHODS
  The radiographic and clinical data of 92 consecutive patients who underwent primary placement of PS in the lumbar spine were retrospectively analyzed. Postoperative computed tomography scans were used to assess the accuracy of screw placement using both quantitative and anatomic criteria.
  
  
  RESULTS
  A total of 85 patients with 410 screws were included in the study. Twenty screws were malpositioned, thus the overall accuracy was 95.12%. Of all levels instrumented the breach rate for the L1 level was highest (21.43%) and the difference was statistically significant. Two screws in 2 patients were symptomatic, causing radicular pain. Both underwent successful revisions.
  
  
  CONCLUSIONS
  The proposed method of PS placement is safe and reliable for all levels from L2 to S1, with the accuracy similar to image-guided navigation systems.
authors.affiliation: *Department of Neurosurgery, Specialist Medical Center, Polanica-Zdroj †Department of Neurosurgery, Regional Medical Center, Opole ‡Department of Orthopedics and Traumatology, University of Medical Sciences, Poznan, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Miekisiak
authors.forename: Piotr
authors.initials: P
authors.lastname: Kornas
authors.forename: Maciej
authors.initials: M
authors.lastname: Lekan
authors.forename: Wladyslaw
authors.initials: W
authors.lastname: Dacko
authors.forename: Dariusz
authors.initials: D
authors.lastname: Latka
authors.forename: Jacek
authors.initials: J
authors.lastname: Kaczmarczyk
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000453:epidemiology / Q000628:therapy; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D019637:Orthopedic Procedures / Q000379:methods*; D065289:Pedicle Screws; D011183:Postoperative Complications / Q000453:epidemiology / Q000628:therapy; D012189:Retrospective Studies; D012445:Sacrococcygeal Region; D013123:Spinal Fusion / Q000379:methods*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult