title: Subject-specific finite element analysis of the carpal tunnel cross-sectional to examine tunnel area changes in response to carpal arch loading.
abstract: BACKGROUND
  Manipulating the carpal arch width (i.e. distance between hamate and trapezium bones) has been suggested as a means to increase carpal tunnel cross-sectional area and alleviate median nerve compression. The purpose of this study was to develop a finite element model of the carpal tunnel and to determine an optimal force direction to maximize area.
  
  
  METHODS
  A planar geometric model of carpal bones at hamate level was reconstructed from MRI with inter-carpal joint spaces filled with a linear elastic surrogate tissue. Experimental data with discrete carpal tunnel pressures (50, 100, 150, and 200mmHg) and corresponding carpal bone movements were used to obtain material property of surrogate tissue by inverse finite element analysis. The resulting model was used to simulate changes of carpal arch widths and areas with directional variations of a unit force applied at the hook of hamate.
  
  
  RESULTS
  Inverse finite element model predicted the experimental area data within 1.5% error. Simulation of force applications showed that carpal arch width and area were dependent on the direction of force application, and minimal arch width and maximal area occurred at 138° (i.e. volar-radial direction) with respect to the hamate-to-trapezium axis. At this force direction, the width changed to 24.4mm from its initial 25.1mm (3% decrease), and the area changed to 301.6mm2from 290.3mm2(4% increase).
  
  
  CONCLUSIONS
  The findings of the current study guide biomechanical manipulation to gain tunnel area increase, potentially helping reduce carpal tunnel pressure and relieve symptoms of compression median neuropathy.
authors.affiliation: Hand Research Laboratory, Cleveland Clinic, Cleveland, OH, United States; Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH, United States.
authors.forename: Piyush
authors.initials: P
authors.lastname: Walia
authors.affiliation: Computational Biomodeling (CoBi) Core, Cleveland Clinic, Cleveland, OH, United States; Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH, United States.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Erdemir
authors.affiliation: Hand Research Laboratory, Cleveland Clinic, Cleveland, OH, United States; Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH, United States; Department of Orthopaedic Surgery, Cleveland Clinic, Cleveland, OH, United States; Department of Physical Medicine and Rehabilitation, Cleveland Clinic, Cleveland, OH, United States. Electronic address: liz4@ccf.org.
authors.forename: Zong-Ming
authors.initials: ZM
authors.lastname: Li
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002348:Carpal Bones / Q000502:physiology; D002349:Carpal Tunnel Syndrome / Q000503:physiopathology*; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008475:Median Nerve / Q000502:physiology; D008954:Models, Biological; D013710:Tendons / Q000502:physiology; D051222:Trapezium Bone / Q000502:physiology; D014955:Wrist Joint / Q000503:physiopathology*
keywords: Carpal tunnel; Cross-sectional area; Mechanics