Experimentally and Theoretically Narrowing Carpal Arch Width to Increase the Area Formed by the Transverse Carpal Ligament

Carpal tunnel syndrome is conventionally treated by open and endoscopic release surgeries in which transecting the transverse carpal ligament (TCL) relieves mechanical insults around the median nerve. The TCL release surgeries yield an increase in the tunnel cross-sectional area particularly within the volar aspect of the tunnel, the arch area, where the median nerve is located. As a result of increased arch area, post-operative follow-up studies using MRI confirmed a significant volar migration of the median nerve [1]. However, transecting the TCL compromises critical biomechanical roles of the carpal tunnel [2], and therefore, it is imperative to investigate an alternative method for treating carpal tunnel syndrome patients while preserving the TCL. Li et al. suggested that increasing the TCL length and narrowing the carpal arch width (CAW) as potential alternatives for increasing the arch area [3]. However, the data from their application of palmarly directed forces to the TCL from inside of the tunnel showed that the TCL length remained relatively constant while the carpal bones were mobilized to increase the arch area [3]. The purpose of this study was to investigate the relationship between CAW narrowing and the TCL-formed arch area by experimental and geometrical modeling.