Finite element modeling of the finger flexion effect on median nerve compression

Carpal tunnel syndrome is a neurological disorder resulting in loss of sensory and motor functions in the hand. The median nerve passing through the carpal tunnel is squeezed by the surrounding tissues. In contrast to finite-element modeling, existing clinical methods for determining carpal tunnel syndrome do not demonstrate pressure in the median nerve. Patient-specified knowledge of pressure in the median nerve is a key factor in carpal tunnel syndrome. MRI and CT scans are used to build three-dimensional geometry of the carpal tunnel and index finger. The stress-strain state is obtained by finite-element modeling. The behavior of the soft tissues are considered hyperelastic and are described by the first-order Ogden constitutive model. The calculations are performed in the ANSYS software package. The results showed that with a slight flexion of the index finger, the median nerve experiences a pressure of 50 Pa. It has also been shown that dissection of the transverse ligament of the hand can lead to an increase in pressure in the median nerve up to 70 Pa. The model built in this study will make it possible to assess the influence of many other mechanical factors on median nerve compression.