Trigger Finger Workup

Updated: Jan 17, 2023
  • Author: Satishchandra Kale, MD, MBBS, MBA, MCh(Orth), FRCS(Edin), FRCS(Tr&Orth); Chief Editor: Harris Gellman, MD  more...
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Approach Considerations

Trigger finger (TF) is a clinical diagnosis. Occasionally, the nodule in the tendon is easily felt, and a palpable and audible click can be appreciated when the triggering is relieved with forced extension of the digit.

As a rule, no lab tests are needed in the diagnosis of TF. If there is a concern regarding an associated, undiagnosed condition, such as diabetes mellitus (DM), rheumatoid arthritis (RA), or another connective tissue disease, tests such as those assessing glycosylated hemoglobin (HbA1c), fasting blood sugar, or rheumatoid factor (RF) should be ordered.



Radiography rarely is indicated in TF. [5] Hand radiographs are performed only if abnormal pathology (eg, abnormal sesamoids, loose bodies in the metacarpophalangeal [MCP] joint, osteoarthritic spurs on the metacarpal head, or avulsion injuries of collateral ligaments) is suspected.

Radiographs are helpful to exclude osteoarthritis, fracture malunion, foreign body, or a large sesamoid bone that is affecting interphalangeal (IP) joint motion.


Histologic Findings

The A1 pulley exhibits a marked degree of hypertrophy, described as a white, cicatricial, collarlike thickening. Microscopy demonstrates degeneration, cyst formation, and plasma-cell infiltration. Microscopic studies have also shown chondrocytic proliferation of type III collagen instead of chondrocyte presence in the normal innermost or friction layer of the A1 pulley. [33] The amount of extracellular matrix is increased significantly when compared with controls.



Green's classification of triggering is used only for clinical grading and documentation. No correlation has been established between the grading scheme and the outcome following injection therapy. The various grades are defined as follows [34] :

  • Grade I (pretriggering) - Pain; history of catching that is not demonstrable on clinical examination; tenderness over the A1 pulley
  • Grade II (active) - Demonstrable catching, but with the ability to actively extend the digit maintained
  • Grade III (passive) - Demonstrable locking in which passive extension is required (grade IIIA) or in which the patient is unable to actively flex (grade IIIB)
  • Grade IV (contracture) - Demonstrable catching, with a fixed flexion contracture of the proximal interphalangeal (PIP) joint