title: Estimating Scaphoid Lengths Using Anatomical Measurements in the Wrist.
abstract: OBJECTIVE
  In reconstructive surgery of scaphoid nonunions with humpback deformity, some surgeons recommend restoration of the normal scaphoid length whereas others overexpand the normal length to ensure carpal realignment and prevent late collapse. To be able to define overexpansion and investigate which levels of overexpansion yield optimal clinical results, a precise method for estimating the original scaphoid length is required. The purpose of this anatomic study was to investigate the precision of estimating normal scaphoid lengths based on intact adjacent bone dimensions, compared with using the contralateral scaphoid length.
  
  
  METHODS
  From bilateral computed tomographic scans of 28 healthy wrist pairs, 3-dimensional virtual bone models were created. The left and right scaphoid lengths were determined at the central axis. The capitate length at the central axis and the distal radius width served to derive an ipsilateral scaphoid length estimate. Estimation precision for individual cases was based on the 95% range (±1.96 × SD) of the observed differences between the actual and estimated lengths.
  
  
  RESULTS
  On average, the capitate length was 10% smaller than the scaphoid length; the radius width was 9% larger. Consequently, we averaged the capitate length and radius width for ipsilateral estimations. The average difference between the scaphoid length and the latter ipsilateral estimate was 0.1 mm. The average contralateral scaphoid length difference was also 0.1 mm. Estimation precisions, however, were ±2.2 and ±1.4 mm, respectively.
  
  
  CONCLUSIONS
  Scaphoid length estimation based on the contralateral scaphoid is more precise than the estimating scaphoid length using the ipsilateral radius and capitate.
  
  
  CONCLUSIONS
  Scaphoid overexpansion can be ensured if the restored length is at least 1.4 mm longer than the contralateral length. This may be valuable information when establishing a target length for reconstruction and investigating the consequences of scaphoid overexpansion on clinical function, such as range of motion, which are currently unknown.
authors: Department of Plastic, Reconstructive, and Hand Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. Electronic address: paultenberg@hotmail.com.
authors: Paul W L
authors: PW
authors: Ten Berg
authors: Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors: Johannes G G
authors: JG
authors: Dobbe
authors: Department of Orthopaedics, Lievensberg Hospital, Bergen Op Zoom, The Netherlands.
authors: Geert
authors: G
authors: Meermans
authors: Department of Plastic, Reconstructive, and Hand Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors: Simon D
authors: SD
authors: Strackee
authors: Department of Orthopaedics, Monica Hospital, Antwerp, Belgium.
authors: Frederik
authors: F
authors: Verstreken
authors: Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors: Geert J
authors: GJ
authors: Streekstra
mesh_terms: D000328:Adult; D001837:Body Weights and Measures; D051224:Capitate Bone / Q000000981:diagnostic imaging*; D003198:Computer Simulation; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D011884:Radius / Q000000981:diagnostic imaging*; D021361:Scaphoid Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D014953:Wrist / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: Scaphoid nonunion; anatomy; nonunion; reconstruction; scaphoid