A carpal tunnel release is the most common hand surgery that I perform. The second most common is a trigger finger release.
A trigger finger (or trigger thumb) involves painful snapping or locking of the fingers or thumb. The medical name for this condition is stenosing tenosynovitis. Stenosing refers to the narrowing of an opening or passageway in the body. Tenosynovitis refers to inflammation of the outer covering of the tendons that bend and extend the fingers and thumb.
- The tendons are tough, fibrous cords that connect the muscles of the forearm to the bones of the fingers and thumb.
- This muscle and tendon system enables one to bend the fingers inward when making a fist, and extend them out straight.
- The tendons glide through a protective covering called the tendon sheath.
- The sheath is like a tunnel.
- It is lined with a thin membrane called synovium. The synovial lining helps reduce friction as the tendons glide through the tendon sheath.
- Areas of dense fibrous tissue called annular bands or pulleys are also part of the tendon sheath.
Pathology - The Trigger Finger
A trigger finger (or trigger thumb) is often caused by inflammation of the synovial sheath surrounding the tendons. It may also result from enlargement of the tendon itself, or narrowing of the first annular band (A1 pulley).
When inflamed, the normally thin covering of the sheath may be thickened to several times its normal size. This reduces the amount of space through which the tendons are able to pass. The tendon is no longer able to glide freely through the sheath, and the tendon itself may swell up in a balloon-like mass at the point where it tries to pass through the tunnel.
Upon forceful bending of the finger or thumb, the enlarged portion of the tendon is dragged through the constricted opening. This motion is often accompanied by a painful snap, and the finger or thumb may be locked in a bent position. Straightening the finger or thumb may require using the non-affected hand to actually pull the finger back into an extended position, causing another painful snap as the swollen portion of the tendon passes back through the sheath.
The exact cause of trigger finger or thumb is not always readily apparent. In many cases, however, this condition may be the result of repeated strain of this area due to work or hobby activities. Tasks that require repetitive grasping or the prolonged use of tools (scissors, screwdrivers, etc.) which press firmly on the tendon sheath at the base of the finger or thumb may irritate the tendons and result in thickening of the tendons themselves or the tendon sheath. Symptoms of trigger finger may also be associated with conditions such as...
- rheumatoid arthritis
Signs and Symptoms
One of the first symptoms may be discomfort in the area of the palm directly beneath the affected finger or thumb. This region marks the entrance of the tendon sheath (the A1-pulley area).
As the disease progresses, patients notice painful snapping sensations during finger motion. If the disorder is not treated, the finger or thumb may actually become locked in a bent position (or less often, in an extended position).
This joint may appear to jump or lock, but the true problem is found in the tendon sheath. It is here that the smooth gliding of the tendon becomes obstructed.
- Conservative treatment is worthwhile, unless the finger or thumb is in an unmovable locked position:
- avoidance of activities that provoke triggering
- oral anti-inflammatory pain medications
- a cortisone injection into the tendon sheath to decrease inflammation
- When conservative treatment fails, or when the finger or thumb remains in a locked position, I usually recommend surgery....
- small incision in the palm at the base of the finger or thumb
- cut (release) the first annular band of the tendon sheath
- The constriction of the tendon is relieved.
- If the surgery is done under local anesthesia without heavy sedation, I usually ask the patient to actively move the tendon during the surgery to confirm that the triggering has resolved.
- The whole surgery takes less than 20 minutes.
- In rare cases, such as in patients with rheumatoid arthritis, the surgery may be more extensive. A portion of the tendon or the synovial covering may require removal.
Following surgery, a light dressing is applied to protect the incision yet allow for motion of the finger or thumb. The dressing is removed 10-14 days following surgery. Activities requiring normal use of the affected hand may be restricted depending on your specific activity level.