title: Three-Dimensional Analysis of Acute Scaphoid Fracture Displacement: Proximal Extension Deformity of the Scaphoid.
abstract: BACKGROUND
  Our goal was to analyze the movement of acute scaphoid waist fracture fragments and adjacent bones in a common coordinate system. Our hypothesis was that the distal scaphoid fragment flexes and pronates and the proximal fragment extends.
  
  
  METHODS
  Computed tomography (CT) scans of patients diagnosed with an acute scaphoid waist fracture were evaluated using a 3-dimensional (3D) model. The scans of 57 nondisplaced and 23 displaced fractures were compared with a control group of 27 scans showing no pathological involvement of the wrist. Three anatomical landmarks were labeled on the distal and proximal fragments of the scaphoid, the lunate, and the trapezium. Each set of labels formed a triangle representing the bone or fragment. Four landmarks were labeled on the distal radial articular surface and used to create a common coordinate system. The position of each bone or fragment was calculated in reference to these coordinates.
  
  
  RESULTS
  The displaced fracture group showed significant extension, supination, and volar translation of the proximal scaphoid fragment when compared with the other groups. The lunate tended toward a supinated position, which was not statistically significant. The distal scaphoid fragment and the trapezium showed no movement.
  
  
  CONCLUSIONS
  In acute displaced scaphoid fractures, it is the proximal fragment that displaces and should be reduced.
  
  
  CONCLUSIONS
  The typical "humpback" deformity is actually a "proximal extension" deformity, the consequence of displacement of the proximal fragment of the scaphoid (with the lunate). Manipulating only the proximal fragment (with the lunate) may be technically easier and more effective than manipulating both fragments.
authors.affiliation: 1Department of Orthopaedic Surgery, Hadassah-Hebrew University Medical Center, Jerusalem, Israel 2School of Engineering and Computer Science, the Hebrew University, Jerusalem, Israel 3University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Yonatan
authors.initials: Y
authors.lastname: Schwarcz
authors.forename: Yael
authors.initials: Y
authors.lastname: Schwarcz
authors.forename: Eran
authors.initials: E
authors.lastname: Peleg
authors.forename: Leo
authors.initials: L
authors.lastname: Joskowicz
authors.forename: Ronit
authors.initials: R
authors.lastname: Wollstein
authors.forename: Shai
authors.initials: S
authors.lastname: Luria
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D059925:Anatomic Landmarks; D002348:Carpal Bones / Q000000981:diagnostic imaging; D050723:Fractures, Bone / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008875:Middle Aged; D015588:Observer Variation; D011403:Pronation / Q000502:physiology; D021361:Scaphoid Bone / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods; D014955:Wrist Joint / Q000000981:diagnostic imaging; D055815:Young Adult