title: Tangential View and Intraoperative Three-Dimensional Fluoroscopy for the Detection of Screw-Misplacements in Volar Plating of Distal Radius Fractures.
abstract: BACKGROUND
  Volar locking plate fixation has become the gold standard in the treatment of unstable distal radius fractures. Juxta-articular screws should be placed as close as possible to the subchondral zone, in an optimized length to buttress the articular surface and address the contralateral cortical bone. On the other hand, intra-articular screw misplacements will promote osteoarthritis, while the penetration of the contralateral bone surface may result in tendon irritations and ruptures. The intraoperative control of fracture reduction and implant positioning is limited in the common postero-anterior and true lateral two-dimensional (2D)-fluoroscopic views. Therefore, additional 2D-fluoroscopic views in different projections and intraoperative three-dimensional (3D) fluoroscopy were recently reported. Nevertheless, their utility has issued controversies.
  
  
  OBJECTIVE
  The following questions should be answered in this study; 1) Are the additional tangential view and the intraoperative 3D fluoroscopy useful in the clinical routine to detect persistent fracture dislocations and screw misplacements, to prevent revision surgery? 2) Which is the most dangerous plate hole for screw misplacement?
  
  
  METHODS
  A total of 48 patients (36 females and 13 males) with 49 unstable distal radius fractures (22 x 23 A; 2 x 23 B, and 25 x 23 C) were treated with a 2.4 mm variable angle LCP Two-Column volar distal radius plate (Synthes GmbH, Oberdorf, Switzerland) during a 10-month period. After final fixation, according to the manufactures' technique guide and control of implant placement in the two common perpendicular 2D-fluoroscopic images (postero-anterior and true lateral), an additional tangential view and intraoperative 3D fluoroscopic scan were performed to control the anatomic fracture reduction and screw placements. Intraoperative revision rates due to screw misplacements (intra-articular or overlength) were evaluated. Additionally, the number of surgeons, time and radiation-exposure, for each step of the operating procedure, were recorded.
  
  
  RESULTS
  In the standard 2D-fluoroscopic views (postero-anterior and true lateral projection), 22 screw misplacements of 232 inserted screws were not detected. Based on the additional tangential view, 12 screws were exchanged, followed by further 10 screws after performing the 3D fluoroscopic scan. The most lateral screw position had the highest risk for screw misplacement (accounting for 45.5% of all exchanged screws). The mean number of images for the tangential view was 3 ± 2.5 images. The mean surgical time was extended by 10.02 ± 3.82 minutes for the 3D fluoroscopic scan. An additional radiation exposure of 4.4 ± 4.5seconds, with a dose area product of 39.2 ± 14.5 cGy/cm(2) were necessary for the tangential view and 54.4 ± 20.9 seconds with a dose area product of 2.1 ± 2.2 cGy/cm(2), for the 3D fluoroscopic scan.
  
  
  CONCLUSIONS
  We recommend the additional 2D-fluoroscopic tangential view for detection of screw misplacements caused by overlength, with penetration on the dorsal cortical surface of the distal radius, predominantly observed for the most lateral screw position. The use of intraoperative 3D fluoroscopy did not become accepted in our clinical routine, due to the technical demanding and time consuming procedure, with a limited image quality so far.
authors.affiliation: Trauma Department, Jena University Hospital, Jena, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Rausch
authors.affiliation: Trauma Department, Jena University Hospital, Jena, Germany.
authors.forename: Ivan
authors.initials: I
authors.lastname: Marintschev
authors.affiliation: Trauma Department, Jena University Hospital, Jena, Germany.
authors.forename: Isabel
authors.initials: I
authors.lastname: Graul
authors.affiliation: Trauma Department, Jena University Hospital, Jena, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Wilharm
authors.affiliation: Foot and Ankle Department, Catholic Medical Center, Mainz, Germany.
authors.forename: Kajetan
authors.initials: K
authors.lastname: Klos
authors.affiliation: Trauma Department, Jena University Hospital, Jena, Germany ; Berufsgenossenschaftliche Kliniken Bergmannstrost Halle, Halle, Germany.
authors.forename: Gunther O
authors.initials: GO
authors.lastname: Hofmann
authors.affiliation: Trauma Department, Jena University Hospital, Jena, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Florian Gras
keywords: Distal Radius Fracture; Doenicke View; Imaging; Intraoperative; Screw Penetration