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 200 mmHg) 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. Findings 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 24.4 mm from its initial 25.1 mm (3% decrease), and the area changed to 301.6 mm2 from 290.3 mm2 (4% increase). Interpretation 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.

Electrophysiological, biomechanical, and finite element analysis study of sacral nerve injury caused by sacral fracture

“…In this study, the material parameters of the nerve were determined by simulating the tensile test, and were used to simulate the load that the nerve can bear when it is compressed. Although the real nerve bundle is composed of more fibers of different diameters, it is necessary to use simplified geometry to evaluate the electromechanical equivalence in the 3D finite element model and limit the computational cost ( Walia et al, 2017 ). The mechanical properties of the biomaterials involved in this experiment were assumed to be homogeneous and continuous.…”

A preliminary study of radioulnar wrist compression in improving patient-reported outcomes of carpal tunnel syndrome

“…As we’ve demonstrated, through geometric modeling [ 4 ], in vitro studies [ 6 ], and finite element analysis [ 5 ], carpal arch width narrowing via radioulnar wrist compression is associated with palmar bowing of the transverse carpal ligament, leading to increased arch height and area. This method of carpal tunnel area expansion maintains the tunnel’s structural integrity while also creating more space for the median nerve.…”

“…4 Hand Research Laboratory, Departments of Orthopaedic Surgery and Biomedical Engineering, University of Arizona, Tucson, AZ, USA. 5 Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH, USA. 6 Arthritis Center, University of Arizona, Tucson, AZ, USA.…”

“…When an external force is applied and directed across the width of the wrist in the radioulnar direction, the distance between the trapezium and hook of hamate narrows, bowing the transverse carpal ligament palmarly. The mechanisms of wrist compression for carpal arch space augmentation and its implications to decompress the median nerve have been demonstrated through geometric modeling [4], finite element analysis [5], and in vitro experiments [6], and in vivo study [7]. In particular, radioulnar wrist compression has also been shown to alleviate median Open Access *Correspondence: lizongming@arizona.edu nerve compression and restore impaired neurophysiological and biomechanical functions of the nerve in CTS patients, as indicated by improvements in median nerve flattening [7], nerve mobility [8], cross sectional area [9], and distal motor latency [10].…”

Finite element analysis for transverse carpal ligament tensile strain and carpal arch area

“…Subject-specific FE models based on medical imaging providing representation of patient-specific anatomy have been utilized in many fields. Specifically for the carpal tunnel, previous FE modeling has been used to examine the effects of TCL release on displacement of carpal bones and contact stress in the midcarpal joints (Guo et al, 2009), and carpal arch enlargement under optimal force direction (Walia et al, 2017). However, carpal tunnel FE modeling has paid little attention to the mechanical properties of the various soft tissues, i.e.…”