Publications

Background: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Subject Areas: anatomy and physiology, pathology, histology

Keywords: aging, transverse carpal ligament, median nerve, carpal tunnel, mechanical property

This study highlights significant age-related changes in the TCL and median nerve that contribute to the pathophysiology of CTS in older adults. Structural changes in the TCL, including increased stiffness, fibroblast loss, and collagen disorganization, were accompanied by degeneration of the median nerve, including thinning of connective tissue sheaths, axonal degeneration, and myelin breakdown. These findings provide valuable insights into the mechanisms underlying the higher prevalence and severity of CTS in the elderly, emphasizing the need for targeted interventions to address these age-associated changes.