# Age-dependent changes in the transverse carpal ligament and median nerve: a cadaveric histological and biomechanical study

## TL;DR

This study shows that aging causes structural and mechanical changes in the wrist ligament and median nerve, increasing the risk of carpal tunnel syndrome in older people.

## Contribution

The study provides novel biomechanical and histological insights into age-related changes in the transverse carpal ligament and median nerve using cadaveric specimens.

## Key findings

- TCL stiffness increases with age, while elasticity and relaxation decrease.
- Histology shows disorganized collagen and reduced fibroblast density in older specimens.
- Median nerve shows thinning connective tissue and diminished myelin sheaths with age.

## Abstract

Age-related alterations in the transverse carpal ligament (TCL) and the median nerve are thought to increase susceptibility to carpal tunnel syndrome in older individuals. This study aimed to investigate the mechanical properties of the TCL and histological changes in both the TCL and the median nerve in cadavers across a wide age range.

Fifty formalin-embalmed cadavers (40–93 years old) were studied, yielding 100 TCL specimens. A digital palpation device (MyotonPRO) was used in situ to measure TCL dynamic stiffness, elasticity (logarithmic decrement), mechanical stress relaxation time, and creep at proximal, middle, and distal regions. After testing, each TCL and corresponding median nerve were excised. Masson’s trichrome staining and scanning electron microscopy were performed to assess collagen fiber organization, fibroblast density, and nerve structure. Pearson’s correlation was used to determine associations between TCL properties and age.

An age-dependent increase in TCL stiffness was observed, alongside decreased elasticity, relaxation time, and creep. Histological analyses revealed reduced fibroblast density, disorganized collagen fibers with large clefts between bundles, and increased fine collagen meshwork in interfascicular matrix in older specimens. Furthermore, thinning of connective tissue layers surrounding the median nerve and diminished myelin sheaths were noted with advancing age.

This cadaveric study reveals that the TCL stiffens and becomes structurally disorganized with advancing age, paralleled by degenerative changes in the median nerve. Such age-related alterations may predispose elderly individuals to a higher risk of carpal tunnel syndrome, underscoring the need for targeted preventive and therapeutic strategies.