Trace elements in human tendons and ligaments.

Tendons and ligaments are key structures in promoting joint movement and maintaining joint stability. Although numerous reviews have detailed their structure, molecular composition, and biomechanical properties, far less attention has been paid to their content of trace elements. Tendons and ligaments are generally rich in calcium, sulfur, and phosphorus, although there are intriguing differences between one tendon/ligament and another. Furthermore, there can be significant regional variations that correlate with the presence or absence of fibrocartilage in the "wrap-around" regions of tendons or ligaments, where they change direction and press against bone. Here, their sulfate and calcium contents are particularly high. This is undoubtedly associated with the high levels of proteoglycans that are found in these cartilaginous tissues and the occasional presence of sesamoid bones within them.