Trigger Finger

Stenosing tenosynovitis of the finger flexor tendon is known as “trigger finger.” This is one of the more common forms of tendonitis involving the hand. Trigger finger most often occurs in the thumb, middle and ring fingers. The term “trigger finger” is used because of the snapping and/or locking sensation that occurs when the patient actively flexes and extends the finger.

Anatomy/Pathophysiology

Normally, the tendons glide smoothly through their individual tendon sheaths or tunnels. (Diagram 1) When the tenosynovium, which lines the tendon sheath, becomes inflamed and swollen, its diameter is reduced. The triggering sensation is caused by the disproportion in size between the flexor tendon and its sheath. (Diagram 2)

Causation

The most common form of trigger finger occurs in otherwise healthy individuals who engage in activities that involve repetitive gripping and pinching. A secondary form of trigger finger occurs with other disease processes such as rheumatoid arthritis, gout and diabetes. It is not uncommon to find several fingers involved at the same time. Diabetics in particular may present with multiple trigger fingers. Trigger thumb occurs by the same mechanism as trigger finger. There is also a congenital form of trigger thumb and finger seen in infants.

Clinical Presentation

Most patients present with a history of gradual onset of pain and swelling in the distal palm and stiffness of the involved finger. The patient usually localizes their problems to the finger's middle joint. This is the joint that feels locked. In fact, the tendon is actually entrapped at the distal palm. This can be appreciated by palpitating the distal palmar region and having the patient flex and extend their digit. A nodule on the flexor tendon can be palpated as it pops through the constricting tendon sheath. (Diagram 3) A complication of trigger finger is a joint flexion contracture. This may remain even after successful surgical release of the trigger finger. This is particularly common in older individuals with underlying degenerative arthritis. Other presentations of trigger finger are simply a stiff digit with a restricted range of motion but without triggering. In these cases, the tendon sheath becomes so swollen that the tendon cannot glide through the sheath. X-rays are helpful in identifying underlying arthritis, which may complicate management of trigger fingers. Trigger finger is often associated with other inflammatory conditions of the hand, most commonly carpal tunnel syndrome.

Nonoperative Treatment

Nonoperative treatment will include splinting the finger in extension to prevent triggering, the use of anti-inflammatory medication, ergonomic changes in the work place, and modification of activity to prevent forceful, repetitive gripping and pinching on a repetitive basis. Local steroid injection has a higher success rate in early forms of trigger finger. However, poor prognostic factors include long duration, multiple trigger digits, diabetes and rheumatoid arthritis. Most patients are not content to spend many weeks being treated with conservative measures. Fortunately, surgical management is simple, reliable and a permanent solution.

Surgical Management

Surgery is usually performed with local anesthesia. It is done as an outpatient procedure. A small incision is made in the distal palmar region. The first section of the tendon sheath is released. Patients are encouraged to use their hand immediately. The most important part of rehabilitation is to maintain a full range of motion. There is a minimal disability or impairment of function following surgery. The only precaution is to protect the area of the incision, which is sensitive to pressure for a few weeks. Although surgical management of trigger finger is usually a simple straightforward procedure, there are potential complications. There may be persistent pain and triggering if there is significant swelling of the flexor tendon sheath. Joint stiffness and permanent contracture may occur. Other concerns include restricted range of motion, scar tenderness, infection, tendon adhesions and nerve injury. Surgical management of trigger finger is highly effective and a safe procedure in relieving the mechanical entrapment of the flexor tendon. It is emphasized that this procedure is reserved for experienced hand surgeons in order to avoid complications. The assistance of occupational therapy after surgery is helpful for a complete recovery. In summary, trigger finger thumb is one form of tendonitis. Tendonitis conditions are usually overuse injuries that are a frequent problem in certain occupations, hobbies, and athletics. They occur secondary to repetitive and moderately stressful forces on the tendons. Surgery is very successful in the management of trigger fingers. The prevention of tendonitis in general requires a change in the patterns of activity and ergonomic changes at the workplace.