These connective tissue tubes, which are filled with a lubricating fluid, surround the tendon like a tunnel. The tendon itself is enveloped by the tendinous membrane. If this becomes inflamed or undergoes change due to permanent overstrain, dragging pain occurs along the course of the tendon. Although the cause is usually overstrain of the tendon, an inflammatory joint condition may also cause the symptoms. The tendons of the wrist are most often affected, but the condition can also occur in any other tendon with a synovial sheath. In most cases the inflammation is due to chronic overstrain, not an infection.

The symptoms are severe and recurrent dragging pain. Initially they occur during movement, but later they appear at rest as well. Local heat, swelling and redness may be apparent. If the affected joint is not rested or immobilised, the symptoms grow progressively worse until the joint can no longer be used due to the pain. The affected site is tender to pressure, and a grinding sound may be heard on movement.