title: Displaced scaphoid fractures treated with open reduction and internal fixation with a cannulated screw.
abstract: BACKGROUND
  This study was performed to determine if the accuracy of screw placement was improved with use of the Herbert-Whipple cannulated screw compared with use of the AO/ASIF cannulated screw and also to evaluate the functional results in patients with an acute displaced fracture of the waist of the scaphoid treated with open reduction and internal fixation with a cannulated screw.
  
  
  METHODS
  We retrospectively reviewed the results for thirty-five patients in whom an acute displaced fracture of the waist of the scaphoid had been treated with internal fixation with use of a cannulated screw. The patients were divided into two groups; Group 1 consisted of nineteen patients managed with a 3.5-millimeter cannulated AO/ASIF screw from 1990 through 1997, and Group 2 consisted of sixteen patients managed with a Herbert-Whipple screw from 1993 through 1997.
  
  
  RESULTS
  There were no clinical or radiographic differences between the two groups. The average time to union (and standard deviation), confirmed with tomography, was 4.2 +/- 1.2 months for Group 1 and 4.0 +/- 1.2 months for Group 2. Both screws significantly improved the alignment of the scaphoid and decreased carpal collapse (p < 0.01). Importantly, the use of either cannulated screw improved the height-to-length ratio and the lateral intrascaphoid angle, which were correlated with an increase in the range of motion of the wrist (r = 0.584 and 0.625). In addition, both screws allowed for accurate placement in the central portion of the proximal pole. Regardless of the type of screw used, the time to union increased with increasing age of the patient (r = 0.665) and with increasing initial displacement of the fracture (r = 0.541). Within both groups, the time to union was longer for the patients who smoked (p < 0.01).
  
  
  CONCLUSIONS
  Within both groups, cannulated screw fixation maintained the corrected fracture alignment and promoted healing and return of function. Our study shows cannulated screws to be a safe and effective method of treatment.
authors.affiliation: Department of Orthopaedics, University of Washington Medical Center, Seattle 98195, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Trumble
authors.forename: M
authors.initials: M
authors.lastname: Gilbert
authors.forename: L W
authors.initials: LW
authors.lastname: Murray
authors.forename: J
authors.initials: J
authors.lastname: Smith
authors.forename: G
authors.initials: G
authors.lastname: Rafijah
authors.forename: W V
authors.initials: WV
authors.lastname: McCallister
mesh_terms: D000328:Adult; D001863:Bone Screws; D002348:Carpal Bones / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery*; D004867:Equipment Design; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D014954:Wrist Injuries / Q000601:surgery; D014955:Wrist Joint