Applied Evidence

Recognizing and treating trigger finger

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References

TF occurs when the tendon sheath, most commonly at the first annular pulley (A1), or the flexor tendons thicken due to fibrocartilaginous metaplasia. This results in impaired gliding motion of the flexor tendons.8 The stenosed A1 pulley can lead to pinching of the flexor tendons and cause the formation of a nodule on the FDS tendon at its bifurcation.9 The nodule of the FDS bifurcation moves proximal to the A1 pulley when the finger is flexed. Upon extension, the tendon nodule may get caught on the A1 pulley. This prevents smooth extension and is the source of pain and triggering (FIGURE 1). In a similar manner, thumb triggering is the result of a stenosed A1 pulley creating a nodule on the FPL tendon, which prevents smooth gliding of the FPL.

The pathology of trigger finger

What you’ll see

TF is characterized by locking, popping, or clicking at the base of the finger or thumb.7,10 A small nodule may be palpated on the palmar aspect of the MCPJ when the finger is flexed. This nodule will then move distally when the finger is extended. Patients will present with the affected digit in a flexed position and will have difficulty extending the digit. In some cases, the patient may have to use the other hand to straighten the affected digit. In more severe cases, the digit may be fixed in a position of flexion or extension. The severity of triggering is commonly graded by the Green’s classification system (see TABLE11).

Green’s classification system

Is it Dupuytren contracture, trigger finger, or something else?

The differential diagnosis for TF includes Dupuytren contracture, MCPJ sprain, calcific peritendinitis, flexor tenosynovitis, diabetic cheiroarthropathy (DCA), rheumatoid arthritis (RA), osteoarthritis (OA), and crystalline arthropathy (gout).5

Dupuytren contracture is usually nonpainful and manifests with a palpable cord in the palm and a fixed flexion contracture that has progressed over time, with no history of catching.

MCPJ sprain is diagnosed with tenderness of the MCPJ and a history of trauma.

Continue to: Calcific peritendinitis

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