Patients with de Quervain’s Tenosynovitis have painful tendons on the thumb side of the wrist. Tendons are the rope-like structures that the muscle uses to pull the bone. You can see them on the back of your hand when you straighten your fingers.
In de Quervain’s Tenosynovitis, the tunnel (the first extensor compartment; see figures 1A and 1B) where the tendons run can narrow, of the tendons can take up extra space in the tunnel. This can be due to a thickening of the soft tissues that make up the tunnel or an increase in the amount of soft tissue within the tunnel. In this condition, hand and thumb motion can cause pain, especially with forceful grasping or twisting.