The aim of this study was to determine differences in the specific collagen types of the transverse carpal ligament (TCL) in patients with carpal tunnel syndrome (CTS) and a control group without CTS.

Surgical specimens from 19 dissected TCLs in patients with idiopathic CTS and 5 controls without CTS were taken (1x1 cm2). We analyzed the manifestations of collagen types I and III by immunohistochemical staining.

We found a homogeneous manifestation of type I and III collagens in the control group. However, in CTS patients, type III collagen was sporadically found around the perivascular and pericellular area, and type I collagen showed no definite differences between the two groups. The cellularity in CTS patients was much lower than that in the control group.

The TCL in CTS patients shows reduced manifestation of type III collagen and less cellularity. These intrinsic changes may play a role in the different manifestations of collagen types in TCL.