title: Assessment of pelvic injuries treated with ilio-sacral screws: injury severity and accuracy of screw positioning.
abstract: The aim of this study was to analyse possible indicative parameters for percutaneous ilio-sacral stabilisation and to identify parameters associated with screw misplacement.
  
  
  
  Cohort study, level I trauma centre.
  
  
  
  (1) unstable pelvic injury, (2) percutaneous ilio-sacral screws placement.
  
  
  
  (1) sacral dysmorphy, (2) failed closed reduction, (3) navigated techniques. Indicative parameters were age, gender, body mass index, number of screws, screw angulation, fracture type and injury severity. End points were ilio-sacral screw position and associated complications. Screw placement accuracy was graded as follows: grade 0, no perforation; grade 1, perforation <2 mm; grade 2, perforation from 2 to 4 mm; grade 3, ≥4 mm perforation.
  
  
  
  Between March 2008 and March 2013, 102 (53 women) patients were included (mean age, 48.5 ± 21.4 years). The Injury Severity Score (ISS) and New Injury Severity Score (NISS) were 18.9 ± 9.9 and 22.3 ± 22.3, respectively. The positions of 137 ilio-sacral screws were analysed. Of all screws, 87.6 % (120) were placed satisfactory (<2 mm perforation). The incidence of screw misplacement was significantly higher in the case of two unilateral S1 screws compared with a single screw (failure rate: two unilateral screws 23.1 % vs single screw 7.0 %; p < 0.05). Screw perforation anterior to the lateral mass (in-out-in) represented the most frequent malposition. Revision was necessary in three cases due to malpositioning. Furthermore, no major complication occurred.
  
  
  
  We conclude, that twofold ilio-sacral screw positioning from one side increases the risk for screw misplacement. In this case, alternative techniques like navigation should be considered. Anterior screw perforation represents a common problem with a high incidence and warrants particular attention.
authors.affiliation: Department of Orthopaedic Trauma, University of Aachen Medical Center, Pauwelsstreet 30, 52074, Aachen, Germany. mpishnamaz@ukaachen.de.
authors.forename: Miguel
authors.initials: M
authors.lastname: Pishnamaz
authors.affiliation: Department of Orthopaedic Trauma, University of Aachen Medical Center, Pauwelsstreet 30, 52074, Aachen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dienstknecht
authors.affiliation: Department of Orthopaedic Trauma, University of Aachen Medical Center, Pauwelsstreet 30, 52074, Aachen, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Hoppe
authors.affiliation: Department of Orthopaedic Trauma, University of Aachen Medical Center, Pauwelsstreet 30, 52074, Aachen, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Garving
authors.affiliation: Department of Orthopaedic Trauma, University of Aachen Medical Center, Pauwelsstreet 30, 52074, Aachen, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Lange
authors.affiliation: Department of Orthopaedic Trauma, University of Aachen Medical Center, Pauwelsstreet 30, 52074, Aachen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Hildebrand
authors.affiliation: Department of Orthopaedic Trauma, University of Aachen Medical Center, Pauwelsstreet 30, 52074, Aachen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Kobbe
authors.affiliation: Department of Orthopaedic Trauma, University of Aachen Medical Center, Pauwelsstreet 30, 52074, Aachen, Germany.
authors.forename: Hans-Christoph
authors.initials: HC
authors.lastname: Pape
mesh_terms: D000328:Adult; D000368:Aged; D001863:Bone Screws / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000379:methods*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D010384:Pelvic Bones / Q000293:injuries* / Q000601:surgery; D012447:Sacrum / Q000601:surgery
keywords: ISS; Ilio-sacral screw; NISS; Pelvic trauma; Sacral fracture