title: Is portable ultrasonography accurate in the evaluation of Schanz pin placement during extremity fracture fixation in austere environments?
abstract: OBJECTIVE
  The purpose of this study was to investigate the efficacy of ultrasonography to confirm Schanz pin placement in a cadaveric model, and the interobserver repeatability of the ultrasound methodology.
  
  
  METHODS
  This investigation is a repeated measures cadaveric study with multiple examiners.
  
  
  METHODS
  Cadaveric preparation and observations were done by an orthopaedic traumatologist and resident, and two general surgery traumatologists.
  
  
  METHODS
  A total of 16 Schanz pins were equally placed in bilateral femora and tibiae. Four examiners took measurements of pin protrusion beyond the distal cortices using first ultrasonography and then by direct measurement after gross dissection.
  
  
  METHODS
  Distal Schanz pin protrusion length measurements from both ultrasonography and direct measurement post dissection.
  
  
  RESULTS
  Schanz pin protrusion measurements are underestimated by ultrasonography (p < 0.01) by an average of 10 percent over the range of 5 to 18 mm, and they display a proportional bias that increases the under reporting as the magnitude of pin protrusion increases. Ultrasound data demonstrate good linear correlation and closely represent actual protrusion values in the 5 to 12 mm range. Interobserver repeatability analysis demonstrated that all examiners were not statistically different in their measurements despite minimal familiarity with the ultrasound methodology (p > 0.8).
  
  
  CONCLUSIONS
  Despite the statistical imparity of pin protrusion measurement via ultrasound compared to that of gross dissection, a consideration of the clinical relevance of ultrasound measurement bias during an austere operating theatre leads to the conclusion that ultrasonography is an adequate methodology for Schanz pin protrusion measurement.
authors.affiliation: Department of Surgery, Division of Orthopaedics and Rehabilitation, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Dahl
authors.affiliation: Department of Surgery, Division of Orthopaedics and Rehabilitation, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Pemberton
authors.affiliation: Department of Surgery, Division of Orthopaedics and Rehabilitation, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Beck
authors.affiliation: Department of Surgery, Division of General Surgery, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Bulent
authors.initials: B
authors.lastname: Cetindag
authors.affiliation: Department of Surgery, Division of General Surgery, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Wohltmann
authors.affiliation: Department of Surgery, Division of Orthopaedics and Rehabilitation, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Mark
authors.initials: M
authors.lastname: McAndrew
mesh_terms: D001858:Bone Nails; D002102:Cadaver; D016267:External Fixators; D005264:Femoral Fractures / Q000000981:diagnostic imaging* / Q000601:surgery; D005592:Fracture Fixation; D006801:Humans; D019095:Point-of-Care Systems; D015203:Reproducibility of Results; D013978:Tibial Fractures / Q000000981:diagnostic imaging* / Q000601:surgery; D014463:Ultrasonography / Q000295:instrumentation*