Catching or locking of a finger caused by inflammation and thickening at the A1 pulley.
Also known as: trigger finger, stenosing tenosynovitis, stenosing flexor tenosynovitis, snapping finger
Overview
Discrepancy in size between an inflamed, thickened flexor tendon and the surrounding A1 pulley at the level of the metacarpophalangeal joint, producing painful catching, snapping, or locking of the affected finger during flexion and extension.
Epidemiology
Lifetime risk approximately 2-3 percent in the general population, rising to 10 percent in adults with diabetes. Most common in middle-aged women. The thumb, middle, and ring fingers are most often involved.
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Question 1MusculoskeletalMedium
A 54-year-old woman with type 2 diabetes presents with several weeks of pain and catching in her right middle finger. She reports that the finger sometimes locks in a bent position, and she has to use her other hand to straighten it back out. Symptoms are worst when she first wakes up. On exam, there is a tender palpable nodule over the distal palmar crease at the base of the affected finger, and active flexion produces a palpable snap on the volar surface. Radiographs of the hand are unremarkable. Which of the following is the most likely diagnosis?
AVolar retinacular ganglion cyst
BInfectious flexor tenosynovitis
CDupuytren palmar contracture
DStenosing flexor tenosynovitis
Reveal answer & full explanation
Correct answer: D — Stenosing flexor tenosynovitis
AVolar retinacular ganglion cyst
BInfectious flexor tenosynovitis
CDupuytren palmar contracture
DStenosing flexor tenosynovitis✓
Why Stenosing flexor tenosynovitis is correct
This condition, commonly called trigger finger, causes painful catching or locking of the digit as a thickened flexor tendon fails to glide smoothly beneath the A1 pulley, producing a mechanical block with flexion and extension.
A tender palpable nodule at the distal palmar crease (over the A1 pulley) plus volar triggering is the classic exam finding, and the patient using the opposite hand to extend a locked digit is the textbook history.
Diabetes is a major risk factor (lifetime risk rises from roughly 2-3% to about 10%), and middle-aged women and the thumb, middle, and ring fingers are most commonly affected, all consistent with this patient.
Why the others are wrong
Dupuytren palmar contracture produces a painless palmar nodule with a longitudinal fibrous cord and fixed flexion contracture, but without true catching or triggering; this patient has painful snapping, not a painless cord.
Volar retinacular ganglion cyst is a small firm cyst arising from the flexor tendon sheath at the A1 pulley that is tender with gripping, but it does not thicken the tendon itself, so it produces no catching, locking, or palpable snap with active flexion.
Infectious flexor tenosynovitis is a surgical emergency defined by Kanavel signs (fusiform finger swelling, flexed resting posture, tenderness along the tendon sheath, and pain on passive extension); this patient has a discrete nodule and mechanical triggering without diffuse swelling or infectious signs.
Question 2MusculoskeletalMedium
A 54-year-old woman presents with 3 months of painful catching of her right middle finger. She reports that the finger occasionally locks in a bent position and she must use her other hand to straighten it, with stiffness worst on waking. She has type 2 diabetes. On exam there is a tender palpable nodule over the distal palmar crease and audible triggering with active flexion and extension; the finger extends fully with assistance. Radiographs of the hand are unremarkable. Which of the following is the most appropriate initial management?
AIntra-articular steroid injection of the MCP joint
BCorticosteroid injection of the flexor sheath
COpen surgical release of the affected A1 pulley
DPercutaneous needle release of the A1 pulley
Reveal answer & full explanation
Correct answer: B — Corticosteroid injection of the flexor sheath
AIntra-articular steroid injection of the MCP joint
BCorticosteroid injection of the flexor sheath✓
COpen surgical release of the affected A1 pulley
DPercutaneous needle release of the A1 pulley
Why Corticosteroid injection of the flexor sheath is correct
Trigger finger (stenosing tenosynovitis) results from a size mismatch between a thickened flexor tendon and the A1 pulley, producing catching and locking; this patient has a classic Quinnell grade II-III presentation with a palpable A1 pulley nodule and triggering that still corrects.
Guideline-supported first-line conservative care includes activity modification, NSAIDs, MCP night splinting, and corticosteroid injection into the flexor tendon sheath at the A1 pulley, with a 50-80% success rate (lower in diabetics, who should be warned about transient post-injection hyperglycemia).
Injection is the most appropriate initial intervention before any surgical option in a digit that still corrects without a fixed contracture.
Why the others are wrong
Open surgical release of the affected A1 pulley is definitive surgery reserved for failed conservative therapy, fixed flexion contracture, or recurrent triggering; it is second-line, not initial management.
Percutaneous needle release of the A1 pulley is also a surgical option for refractory disease; it is not first-line and carries digital nerve injury risk, particularly in the thumb.
Intra-articular steroid injection of the MCP joint treats MCP joint arthritis, not tendon-pulley pathology; the steroid must reach the flexor tendon sheath at the A1 pulley, and the radiographs here show no joint disease.
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Diabetes mellitus (especially long-standing and insulin-dependent)
Rheumatoid arthritis
Hypothyroidism
Amyloidosis
Repetitive forceful gripping (occupational)
Coexistent carpal tunnel syndrome or de Quervain tenosynovitis
Pathophysiology
Repetitive flexor tendon excursion through the A1 pulley produces microtrauma, fibrocartilaginous metaplasia of the pulley, and tendon nodularity. The thickened tendon cannot glide smoothly beneath the pulley, generating a mechanical block and catching with motion. Progression leads to fixed flexion contracture when the digit cannot be extended.
Clinical presentation
Symptoms
Painful catching or popping with flexion and extension
Patient reports needing to use the other hand to straighten the finger
Stiffness most pronounced upon waking
Volar pain at the distal palm radiating into the digit
Signs / physical exam
Tender palpable nodule at the level of the A1 pulley (over the distal palmar crease)
Audible or palpable triggering with active flexion and extension
Locked digit with passive correction in advanced cases
Multiple involved digits are common in diabetes and rheumatologic disease
Classic findings
Locked finger in flexion that the patient extends with assistance from the opposite hand, accompanied by a palpable nodule at the distal palm.
Differential diagnosis
Dupuytren contracture — Painless palmar nodule with longitudinal cord and fixed flexion contracture without true catching
Flexor tendon rupture — Loss of active flexion with passive ROM preserved; usually traumatic
Sagittal band rupture (boxer's knuckle) — Extensor tendon subluxation at the MCP joint with snapping over dorsum rather than volar surface
MCP joint osteoarthritis or RA — Pain localized to joint, swelling, X-ray changes; no true triggering
Quinnell grading system: I — pain and tenderness without triggering; II — uneven motion with triggering correctable actively; III — locked digit requiring passive correction; IV — fixed flexion contracture.
Labs
Hemoglobin A1c if not previously screened — trigger finger is a sentinel finding for undiagnosed diabetes
TSH and inflammatory markers if multiple digits involved or other systemic features
Imaging
Clinical diagnosis — no imaging required in routine cases
Ultrasound can confirm flexor tendon nodule and pulley thickening in uncertain cases
Diagnostic algorithm
Quinnell Grade
Findings
Typical Management
I
Pain and palpable nodule, no triggering
Activity modification, splint, NSAID
II
Demonstrable triggering, actively correctable
Steroid injection
III
Triggering with passive correction needed
Steroid injection; consider release if fails
IV
Fixed flexion contracture
Surgical A1 pulley release
Quinnell classification of trigger finger severity and the management approach at each stage.
Treatment
First-line
Activity modification and avoidance of forceful gripping
NSAIDs for pain
Night splinting of the MCP joint in extension for 6-8 weeks
Corticosteroid injection (triamcinolone 10-20 mg or methylprednisolone 20-40 mg) into the flexor tendon sheath at the A1 pulley — success rate 50-80 percent in non-diabetics, lower in patients with diabetes
Second-line / adjunct
Second steroid injection if the first provided partial or temporary relief
Percutaneous or open A1 pulley release for failed conservative therapy, fixed contracture, or recurrent triggering
Open release is preferred for the thumb (to protect the radial digital nerve) and for diabetic patients
Complications
Persistent triggering or progression to fixed contracture
Tendon rupture (rare; risk increased with repeated steroid injections)
Digital nerve injury during percutaneous release (especially in the thumb)
Bowstringing of the flexor tendon if both A1 and A2 pulleys are released
PANCE pearls
A new diagnosis of trigger finger warrants screening for diabetes if not already established.
Steroid injection has lower success in diabetics; warn patients about transient hyperglycemia after injection.
Triggering in multiple digits or simultaneous carpal tunnel syndrome should raise suspicion for amyloidosis, particularly transthyretin amyloidosis in older patients.
Kanavel signs differentiate infectious flexor tenosynovitis from trigger finger — that diagnosis is a surgical emergency.
References
AAOS — American Academy of Orthopaedic Surgeons clinical practice guideline on management of trigger finger
ASSH — American Society for Surgery of the Hand evidence-based recommendations for trigger digit
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