Tenosynovitis is where the tendons, the cord-like structures connecting muscle to bone, swell. This causes pain and swelling in the affected area of the body, and stiffness in the joint moved by the tendon. Tenosynovitis occurs most commonly in the wrist and hand, and in this case the tendons that swell are those connecting the muscles in the forearm to the bones in the fingers and thumb. These tendons run through a tunnel or sheath. When they swell they sometimes become too thick for this tunnel and ‘catch’ on it as you try to move the connected finger or thumb. The fingers feel slow and as if they are in danger of locking up as you attempt to move them. This is known as stenosing tenosynovitis, or trigger finger, and is thought to be more common amongst women than men.
The first sign of trigger finger is often a feeling of tenderness in the palm, directly beneath the affected finger or thumb. Sometimes people don’t notice anything is wrong until the finger is starting to catch or lock.
Trigger finger is aggravated by repetitive use, as each time the tendon catches (the trigger), it leads to more inflammation and swelling. A splint can be used to immobilise the affected finger or thumb in an extended position, so the joint can completely rest. Finger exercises can also be helpful, as can steroid injections, although often the trigger finger will return in time. Sometimes surgery is used to widen the opening of the tunnel or sheath that the tendon is catching on, for a more long-term solution.