title: Analysis of the three-dimensional anatomical variance of the distal radius using 3D shape models.
abstract: Various medical fields rely on detailed anatomical knowledge of the distal radius. Current studies are limited to two-dimensional analysis and biased by varying measurement locations. The aims were to 1) generate 3D shape models of the distal radius and investigate variations in the 3D shape, 2) generate and assess morphometrics in standardized cut planes, and 3) test the model's classification accuracy.
  
  
  
  The local radiographic database was screened for CT-scans of intact radii. 1) The data sets were segmented and 3D surface models generated. Statistical 3D shape models were computed (overall, gender and side separate) and the 3D shape variation assessed by evaluating the number of modes. 2) Anatomical landmarks were assigned and used to define three standardized cross-sectional cut planes perpendicular to the main axis. Cut planes were generated for the mean shape models and each individual radius. For each cut plane, the following morphometric parameters were calculated and compared: maximum width and depth, perimeter and area. 3) The overall shape model was utilized to evaluate the predictive value (leave one out cross validation) for gender and side identification within the study population.
  
  
  
  Eighty-six radii (45 left, 44% female, 40 ± 18 years) were included. 1) Overall, side and gender specific statistical 3D models were successfully generated. The first mode explained 37% of the overall variance. Left radii had a higher shape variance (number of modes: 20 female / 23 male) compared to right radii (number of modes: 6 female / 6 male). 2) Standardized cut planes could be defined using anatomical landmarks. All morphometric parameters decreased from distal to proximal. Male radii were larger than female radii with no significant side difference. 3) The overall shape model had a combined median classification probability for side and gender of 80%.
  
  
  
  Statistical 3D shape models of the distal radius can be generated using clinical CT-data sets. These models can be used to assess overall bone variance, define and analyze standardized cut-planes, and identify the gender of an unknown sample. These data highlight the potential of shape models to assess the 3D anatomy and anatomical variance of human bones.
authors.affiliation: Department of General, Trauma and Reconstructive Surgery, University Hospital LMU Munich, Nussbaumstr. 20, Munich, 80336, Germany. sebastian.baumbach@med.uni-muenchen.de.
authors.forename: Sebastian F
authors.initials: SF
authors.lastname: Baumbach
authors.affiliation: Department of General, Trauma and Reconstructive Surgery, University Hospital LMU Munich, Nussbaumstr. 20, Munich, 80336, Germany.
authors.forename: Jakob
authors.initials: J
authors.lastname: Binder
authors.affiliation: Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Getreidemarkt 9, Vienna, 1060, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Synek
authors.affiliation: Department of Clinical Radiology, University Hospital LMU Munich, Nussbaumstr. 20, Munich, 80336, Germany.
authors.forename: Fabian G
authors.initials: FG
authors.lastname: Mück
authors.affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, University Hospital LMU Munich, Campus Grosshadern, Marchioninistraße 15, Munich, 81377, Germany.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chevalier
authors.affiliation: Department of General, Trauma and Reconstructive Surgery, University Hospital LMU Munich, Nussbaumstr. 20, Munich, 80336, Germany.
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Euler
authors.affiliation: Computational Imaging Research Laboratory, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, 1090, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Langs
authors.affiliation: Computational Imaging Research Laboratory, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, 1090, Austria.|Software Competence Center Hagenberg GmbH, Softwarepark 21, Hagenberg, 4232, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Fischer
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D011884:Radius / Q000033:anatomy & histology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Anatomical model; Computed tomography; Distal radius; Image processing; Statistical model