title: The effect of landmarks and bone motion on posture-related changes in carpal tunnel volume.
abstract: BACKGROUND
  Deviated wrist postures have been linked to carpal tunnel syndrome development, yet the effect of posture on carpal tunnel volume remains unclear. The purposes of this study were (i) to evaluate the effect of boundary definitions on tunnel volume estimates in neutral and non-neutral (30 degrees flexion, 30 degrees extension) wrist postures and (ii) to develop a biomechanical wrist simulation to predict posture-related changes in tunnel volume.
  
  
  METHODS
  Two carpal tunnel volume measures were calculated using (i) ulnar bony landmarks and (ii) radial and ulnar bony landmarks identified directly from magnetic resonance imaging (MRI) scans. A third volume measure combined computerized tunnel reconstructions with modelled bone surfaces to calculate an anatomically landmarked volume. Six individual simulations were then generated to predict volume in the flexed and extended postures based on individual carpal bone motions.
  
  
  RESULTS
  Boundary definitions influenced the absolute volume in each posture and the relative changes between postures. Relative to fully reconstructed volumes, radial and ulnar landmarked volumes were 15-25% larger across postures (681 (SD 467) mm(3); P=0.01), while the ulnar-only landmarked volumes were 10-20% smaller (562 (343) mm(3); P<0.01). Simulation predicted volumes were not significantly different from the reconstructed anatomically landmarked volumes, with less inter-individual variability between postures compared to MRI-based volumes.
  
  
  CONCLUSIONS
  Comparison of volume measures indicated the importance of capturing posture-related changes in the orientation of the proximal and distal tunnel boundaries, and revealed potential sources of error associated with volume reconstruction. Simulations can enable changes in tunnel dimensions to be related to bone movements throughout a range of motion.
authors: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA.
authors: Jeremy P M
authors: JP
authors: Mogk
authors: Peter J
authors: PJ
authors: Keir
mesh_terms: D002348:Carpal Bones / Q000473:pathology* / Q000503:physiopathology*; D002349:Carpal Tunnel Syndrome / Q000473:pathology* / Q000503:physiopathology*; D003198:Computer Simulation; D006801:Humans; D008953:Models, Anatomic; D008954:Models, Biological; D009068:Movement; D011187:Posture; D016059:Range of Motion, Articular; D014955:Wrist Joint / Q000473:pathology* / Q000503:physiopathology*