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TRIGGER THUMB

Introduction

Trigger thumb, or stenosing tendovaginitis, occurs when the flexor tendons cannot pass through the A-1 pulley smoothly. Whether the pulley thickens, the tenosynovium thickens and/or the tendons deform and develop a "nodule," the result is the same: loss of smooth active flexion and extension in the digit. The digit can lock in flexion or extension or simply be difficult to move without significant pain.

Related Anatomy

  • Caused by anomalous anatomy, including abnormal lumbrical insertion and/or proximal decussation of flexor digitorum sublimis (FDS) tendon
  • Narrowing/thickening of FDS tendon sheath at the A1 pulley level
  • Histology shows non-inflammatory fibrosis; occasionally, chronic inflammatory cells are present

Relevant Basic Science

  • When tendon sheath becomes edematous, the sheath becomes fibrotic and may undergo cartilaginous metaplasia; the tendon becomes thinner and fibrotic

Incidence and Related Conditions

  • More common in women; pregnancy is a predisposing risk factor
  • Predisposing systemic conditions: rheumatoid arthritis, diabetes, gout, amyloidosis, mucopolysaccharidoses
  • Often comorbid with de Quervain’s disease and carpal tunnel syndrome

Differential Diagnosis

  • de Quervain’s disease
  • Dupuytren’s contracture
  • MP joint loose body/dislocation
  • Tendon sheath tumor
  • Intrinsic tendon injury on an irregular metacarpal head
  • Rheumatoid arthritis
Clinical Presentation Photos and Related Diagrams
  • Trigger Thumb with IP joint locked in flexion
    Trigger Thumb with IP joint locked in flexion
Symptoms
Pain near the base of the thumb on palm side of the MP joint
Painful clicking, snapping, catching, triggering or temporary locking of thumb or finger with motion
Flexion or extension contracture due to a permanent partially locked trigger thumb
Limited painful thumb range of motion
Lump or nodule under first flexion crease of the thumb.
Typical History

A patient often notices a click in his or her thumb that eventually becomes painful.  The patient may eventualy be unable to fully flex or extend the thumb without pulling the thumb with the other hand. In chronic cases, the trigger finger may become locked, resulting in fixed-joint contracture

Positive Tests, Exams or Signs
Tenderness A-1 Pulley & Triggering
Flexor Tendon Exam
Range of Motion: Active
Muscle Test and Tendon Exam: Flexor Pollicis Longus (FPL)
Work-up Options
Sonographic studies - Ultrasound
Radiology studies - X-ray
Images (X-Ray, MRI, etc.)
  • Trigger thumbs have normal X-rays
    Trigger thumbs have normal X-rays
Treatment Options
Conservative: 
  • Activity modification
  • Splinting
  • NSAIDS
  • Corticosteroid injections
Operative: 
  • Percutaneous release of A1 pulley (extra risk in the thumb)
  • Open release or excision of the A1 pulley
Treatment Photos and Diagrams
  • Trigger Thumb Incision (Hover over right edge to see more images)
    Trigger Thumb Incision (Hover over right edge to see more images)
  • Trigger Thumb Thickened A-1 pulley
    Trigger Thumb Thickened A-1 pulley
  • Trigger Thumb Thickened A-1 pulley cut edges (arrows)
    Trigger Thumb Thickened A-1 pulley cut edges (arrows)
  • Trigger Thumb - Arrow separates "nota's"section proximally from normal FPL distal to A-1 constriction.
    Trigger Thumb - Arrow separates "nota's"section proximally from normal FPL distal to A-1 constriction.
  • Trigger Thumb - IP Joint now extends easily.
    Trigger Thumb - IP Joint now extends easily.
  • Trigger Thumb - Wound closure
    Trigger Thumb - Wound closure
Complications

Operative: infection, secondary adherence, scar tenderness, mild PIP joint contractures, neurovascular bundle injuries, ulnar drift of digit, bowstringing

Outcomes
  • Conservative: short-term symptom relief; higher rates of long-term recurrence
  • Operative: nearly all patients are satisfied with results
Key Educational Points
  • The radial digital nerve of the thumb is at risk during trigger thumb release in adults and children because of its oblique orientation overlying the A1 pulley.
Practice and CME
References

New Articles

  1. Guler F, Kose O, Ercan EC, et al.  Open versus percutaneous release for the treatment of trigger thumb. Orthopedics 2013;36(10):e1290-4.
  2. Patel RM, Chilelli BJ, Ivy AD, Kalainov DM. Hand surface landmarks and measurements in the treatment of trigger thumb. J Hand Surg Am 2013;38(6):1166-71.

Reviews

  1. Vargas A, Chiapas-Gasca K, Hernández-Díaz C, et al. Clinical anatomy of the hand. Reumatol Clin 2012;8(S2):25-32.
  2. Ryzewicz M, Wolf JM. Trigger digits: principles, management, and complications. J Hand Surg Am 2006;31(1):135-46

Classics

  1. Woolf AE. Trigger Thumb. Proc R Soc Med 1921;14(Surg Sect):142.
  2. Hueston JT, Wilson WF, Soin K. Trigger thumb. Med J Aust 1973;2(23):1044-5