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.
🔒 Free preview limit reached
Keep reading — start your free trial
You've read your 2 free diagnosis previews. Create your free account to unlock the full Trigger Finger (Stenosing Tenosynovitis) outline — plus all 514 diagnoses, 3,500+ board-style questions, flashcards, and an AI tutor. Your 7-day free trial includes everything, and there's no credit card required.
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
Practice Musculoskeletal questions on FirstPassPA
Turn this outline into retention. 3,500+ board-style questions with an AI tutor that explains every answer — free to start, no card required.
Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants.