Trigger Finger

Abstract

Trigger finger is caused by inflammation and swelling of the tendon of the flexor digitorum superficialis resulting from compression by the head of the metacarpal bone. Sesamoid bones in this region may also compress and cause trauma to the tendon. Trauma is usually the result of repetitive motion or pressure on the tendon as it passes over these bony prominences. If the inflammation and swelling become chronic, the tendon sheath may thicken, resulting in constriction. Frequently, nodules develop on the tendon, and they can often be palpated when the patient flexes and extends the fingers. Such nodules may catch in the tendon sheath as they pass under a restraining tendon pulley, thus producing a triggering phenomenon that causes the finger to catch or lock. Trigger finger occurs more commonly in females and in patients with diabetes. Patients engaged in repetitive activities such as hammering, gripping a steering wheel, or holding a horse’s reins too tightly also have a higher incidence of trigger finger. The pain of trigger finger is localized to the distal palm, and tender nodules can often be palpated. The pain is constant and is made worse with active gripping motions of the hand. Patients note significant stiffness when flexing the fingers. Sleep disturbance is common, and patients often awaken to find that the finger has become locked in a flexed position.

On physical examination, tenderness and swelling are noted over the tendon, with maximal point tenderness over the head of the metacarpal. Many patients with trigger finger experience a creaking sensation with flexion and extension of the fingers. Range of motion of the fingers may be decreased because of pain, and a triggering phenomenon may be noted. A catching tendon sign may also be elicited by having the patient clench the affected hand for 30 seconds and then relax but not open the hand. The examiner then passively extends the affected finger, and if he or she appreciates a locking, popping, or catching of the tendon as the finger is straightened, the sign is positive.

Keywords

Trigger thumb, trigger finger, hand pain, tenosynovitis, flexor pollicis longus tendon, flexor digitorum superficialis tendon, repetitive stress injury, diagnostic sonography, ultrasound guided injection

ICD-10 CODE M65.30

The Clinical Syndrome

Trigger finger is caused by inflammation and swelling of the tendon of the flexor digitorum superficialis resulting from compression by the head of the metacarpal bone. Sesamoid bones in this region may also compress and cause trauma to the tendon. Trauma is usually the result of repetitive motion or pressure on the tendon as it passes over these bony prominences. If the inflammation and swelling become chronic, the tendon sheath may thicken, resulting in constriction. Frequently, nodules develop on the tendon, and they can often be palpated when the patient flexes and extends the fingers. Such nodules may catch in the tendon sheath as they pass under a restraining tendon pulley, thus producing a triggering phenomenon that causes the finger to catch or lock. Trigger finger occurs more commonly in females and in patients with diabetes. Patients engaged in repetitive activities such as hammering, gripping a steering wheel, or holding a horse’s reins too tightly also have a higher incidence of trigger finger ( Fig. 56.1 ).

Signs and Symptoms

The pain of trigger finger is localized to the distal palm, and tender nodules can often be palpated. The pain is constant and is made worse with active gripping motions of the hand. Patients note significant stiffness when flexing the fingers. Sleep disturbance is common, and patients often awaken to find that the finger has become locked in a flexed position.

On physical examination, tenderness and swelling are noted over the tendon, with maximal point tenderness over the head of the metacarpal. Many patients with trigger finger experience a creaking sensation with flexion and extension of the fingers. Range of motion of the fingers may be decreased because of pain, and a triggering phenomenon may be noted. A catching tendon sign may also be elicited by having the patient clench the affected hand for 30 seconds and then relax but not open the hand. The examiner then passively extends the affected finger, and if he or she appreciates a locking, popping, or catching of the tendon as the finger is straightened, the sign is positive ( Fig. 56.2 ).