Trigger Finger
Clinical appearance A trigger finger is the locking of one or several fingers in flexion so that the patient may have to pull the finger to straighten it (5-7). Any digit may be affected, however the thumb and the middle finger are most commonly involved. The cause is cartilaginous metaplasia at the first retaining pulley (at the palmar aspect of the metacarpophalangeal joint) which normally becomes taut during finger flexion. When 3 or more digits are affected, the conditions shown in Table 2 should be considered, especially diabetes and hypothyroidism. Differential diagnosis Trigger finger should be distinguished from systemic inflammatory conditions such as rheumatoid arthritis and psoriatic arthritis in which the sheath is diffusely thickened and the trigger phenomenon is unusual. In Dupuytren's contracture, the finger contracture is caused by palmar fascia fibrosis and cannot be reduced. Treatment Spontaneous improvement occurs in only 20% of cases. If untreated, the process can lead to an inability to straighten the finger and a permanent contracture. Trigger finger is treated with corticosteroid infiltrations, as described in the next article. With appropriate treatment, including up to 3 infiltrations, the success rate is over 95%. Complications, including iatrogenic infection or tendon rupture, are rare. Patients should be informed that asymptomatic fat atrophy may occur at the injection site. Rarely, surgery may be required for patients who refuse infiltrations or in whom infiltrations fail. Role of the primary physician Primary care physicians should be familiar with the diagnosis of trigger finger and, with appropriate training, may feel comfortable performing corticosteroid infiltrations of the second, third, or fourth digits. Infiltrations of the thumb and fifth digits are technically difficult and should be performed by those with special expertise (e.g., rheumatologists, hand surgeons, or orthopedic surgeons). Key issues A trigger finger rarely improves without corticosteroid infiltration(s). Involvement of multiple digits may signify a metabolic or infiltrative disorder.
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