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TRIGGER THUMB

Introduction

Introduction

Trigger thumb, or stenosing tenosynovitis of the thumb, occurs when the flexor pollicis longus tendon cannot pass through the A-1 pulley smoothly.1 Whether the pulley thickens or 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 thumb can lock in flexion or extension or simply be difficult to move without significant pain.2,3

Thus, the trigger finger affects hand function and, in severe cases, may lead to limitations in daily routines. In patients with diabetes, the condition is more likely to affect multiple digits and both hands. Initial trigger thumb treatment can include activity modification, splinting and non-steroidal anti-inflammatory medications. Conservative treatment options may include local corticosteroids, and platelet-rich plasma injection.4  Definitive treatment frequently requires surgical release of the A-1 pulley.5

Related Anatomy

  • Narrowing of flexor tendon sheath at the A-1 pulley level

  • Thickening of FPL tendon at the A1 pulley level

  • Histology shows non-inflammatory fibrosis; occasionally, chronic inflammatory cells are present

Relevant Basic Science

  • In patients with trigger fingers the number of chondrocytes and the adjacent extracellular matrix, are notably increased, compared to non-symptomatic patients. When a tendon sheath becomes swollen, the sheath becomes fibrotic and may undergo cartilaginous metaplasia. 

  • The tendon becomes thinner under the area of constriction and thickens proximal to the constriction to form a “nodule.”.6,2

  • While the oblique pulley is narrower by measurement, the A1 pulley is the tightest functionally because the pathological thickening occurs at this location where the tendon-pulley mismatch causes triggering.7,8 


 

Incidence and Related Conditions

  • More common in women; pregnancy is a predisposing risk factor

  • Predisposing systemic conditions: rheumatoid arthritis (RA), diabetes, gout, amyloidosis, mucopolysaccharidoses and Peyronies disease.9 

  • Often trigger thumb is comorbid with DeQuervain’s disease and carpal tunnel syndrome.

Differential Diagnosis

  • DeQuervain’s disease10 

  • Dupuytren’s contracture

  • MP joint loose body/dislocation

  • Tendon sheath tumor

  • RA
     

ICD-10 Codes

  • TRIGGER THUMB

    Diagnostic Guide Name

    TRIGGER THUMB

    ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

    DIAGNOSISSINGLE CODE ONLYLEFTRIGHTBILATERAL (If Available)
    TRIGGER THUMB M65.312M65.311 

    ICD-10 Reference

    Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams
  • Trigger Thumb with IP joint locked in flexion
    Trigger Thumb with IP joint locked in flexion
Symptoms
Pain at the base of the thumb near the volar MP joint and A-1 pulley.
Clicking, catching or triggering of thumb with motion. Can be confused with DeQuervain’s disease in the thumb.10
Crepitus and/or a palpable nodule at the A-1 pulley with motion or palpation
Decreased active range of motion and secondary proximal interphalangeal (IP) contractures
Locking of thumb in flexion
Increased stiffness with or without clicking on awakening
Symptoms may vary with time of day and activities such as prolonged gripping
Typical History

A middle-aged female musician frequently notices a click and/or snapping in her thumb. The snapping has become increasingly painful over time. The patient complains of inability to fully flex the thumb. Her triggering is significantly interfering with her activities, especially playing the bass guitar. If her condition is allowed to become chronic, the trigger thumb may become locked or intermittently locked with a secondary thumb IP joint contracture.

Positive Tests, Exams or Signs
Work-up Options
Images (X-Ray, MRI, etc.)
  • Trigger thumbs have normal X-rays
    Trigger thumbs have normal X-rays
Treatment Options
Treatment Goals

 

      •    Stop the pain, catching, and/or finger locking
      •    Return hand to normal active range of motion with a normal pain-free grip
      •    When making treatment recommendations, consider patients grade according to Green’s classification

Green’s Classification11,14
•Grade I: Pain, history of catching, but no demonstrable trigger
•Grade II: Demonstrable catching, actively correctable
•Grade III: Demonstrable locking, passively correctable
•Grade IV: Fixed contracture

Conservative

  • Activity modification

  • Splinting: Found successful in some cases, without injections or surgery 

  • NSAIDS

  • Corticosteroid injections: Allow two injections before proceeding to operative options. Consider surgery earlier for patients with diabetes.12,13,22

Operative

  • For trigger thumb, open release technique is preferred, with a transverse incision centered over flexor tendon nodule.5 

  • The percutaneous release technique is usually avoided, because digital nerve injury is more likely than with open release surgery.15 

  • Although ultrasound-guided percutaneous release may be effective for other fingers, it is not successful for trigger thumb, because the radial digital nerve of the thumb crosses superficial to the flexor sheath at or near the level of the A1 pulley.9 

  • Some surgeons advise to avoid open release of the A-1 pulley in patients with rheumatoid arthritis.16 

Treatment Photos and Diagrams
  • Trigger Thumb Incision
    Trigger Thumb Incision
  • 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 "Notta's" section proximally from normal FPL distal to A-1 constriction.
    Trigger Thumb - Arrow separates "Notta'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

Work-Up Comments

X-rays are sometimes needed to verify the existence of co-existing arthritis particularly in the IP joint or for other special circumstances. 

Ultrasound can be used to verify the deformity of the flexor tendons, flexor tendon sheath, or volar plate but is not needed when making a routine diagnosis of trigger thumb. When treating trigger thumbs with a cortisone injection, ultrasound can be useful for guiding the needle.

MRI can be used to verify the changes of the flexor tendons, flexor tendon sheath, and the volar plate but is not needed when making a routine diagnosis of trigger thumb. MRI can be helpful when associated lesions such as a tumor are present with a trigger thumb and further evaluation is warranted.

CPT Codes for Treatment Options

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Common Procedure Name
Trigger finger release (trigger thumb release)
CPT Description
Tendon sheath incision trigger finger
CPT Code Number
26055
CPT Code References

The American Medical Association (AMA) and Hand Surgery Resource, LLC have entered into a royalty free agreement which allows Hand Surgery Resource to provide our users with 75 commonly used hand surgery related CPT Codes for educational promises. For procedures associated with this Diagnostic Guide the CPT Codes are provided above. Reference materials for these codes is provided below. If the CPT Codes for the for the procedures associated with this Diagnostic Guide are not listed, then Hand Surgery Resource recommends using the references below to identify the proper CPT Codes.

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CPT 2021 Professional Edition: Spiralbound

Complications

  • Complications of trigger thumb operations may include infection, secondary adherence, scar tenderness, mild PIP joint contractures, neurovascular bundle injuries, ulnar drift of digit and bowstringing. 

  • These complications are rare, but in some cases, they can impede daily function for years after the initial surgery. 

  • It is especially important to diagnose surgical site infections quickly and accurately.17 

Outcomes

 

  • Most patients are satisfied with results for open release surgery for trigger thumb. 

  • General recovery time is about eight weeks. 

  • Patients with diabetes may need prolonged recovery time and have an overall increased rate of complications.18,19 .

Key Educational Points

  • The radial digital nerve of the thumb is at risk during trigger thumb release because of its oblique orientation overlying the A-1 pulley.20 

  • During trigger thumb release preserving all of part of the oblique pulley and all of the A2 pulley helps maintain the biomechanics of the flexor mechanism and pinch strength.

  • Because the patient can easily see the abnormal motion of the thumb IP joint during active triggering, they often think the problem is in the IP joint when, in fact, the locking occurs at the A1 pulley and MP joint area.

  • Failure to preserve the A1 and oblique pulleys during trigger thumb release can cause bowstringing of the FPL tendon.  This can cause thumb deformity, pain, and interfere with pinch.21,22 

References

References 

  1. Ryzewicz M, Wolf JM. Trigger digits: principles, management, and complications. J Hand Surg Am 2006;31(1):135-46.

  2. Moore JS. Flexor tendon entrapment of the digits (trigger finger and trigger thumb). J Occup Environ Med 2000 May;42(5):526-45.

  3. Hueston JT, Wilson WF, Soin K. Trigger thumb. Med J Aust 1973;2(23):1044-5.

  4. Aspinen S, Nordback PH, Anttila T, et al. Platelet-rich plasma versus corticosteroid injection for treatment of trigger finger: study protocol for a prospective randomized triple-blind placebo-controlled trial. Trials 2020;21(1):984.  PMID: 33246497

  5. Sato ES, dos Santos JB, Belloti JC, et al. Treatment of trigger finger: randomized clinical trial comparing the methods of corticosteroid injection, percutaneous release and open surgery. Rheumatology (Oxford). 2012;51(1):93-99.

  6. Sampson SP, Badalamente MA, Hurst LC, Seidman J. Pathobiology of the human trigger finger. J Hand Surg 1991;16A:714-21.  PMID: 1880372

  7. Singh H, et al. Morphometric study of pulleys of the thumb.  Anat Cell Biol. 2018:51(2):83-89.

  8. Schubert MF, et al.  Varied anatomy of the thumb pulley system: implications for successful trigger thumb release.  J Hand Surg Am 2012:37:2278-2285.

  9. White RZ, Sampson MJ. Assessment of short-term response and review of technique of ultrasound-guided percutaneous A1 pulley release for the treatment of trigger finger. Journal of Medical Imaging and Radiation Oncology 2021;65:672-77.

  10. Ayhan E, Cevik K. Triggering thumb is not always a trigger thumb. J Hand Surg Glob Online. 2022;4(6):483-484.

  11. Patel MR, Bassini L. Trigger fingers and thumb: when to splint, inject or operate.  J Hand Surg (Am) 1992,17:110-113.

  12. Stirling PHC, Jenkins PJ, Duckworth AD, et al. Functional outcomes of trigger finger release in non-diabetic and diabetic patients. J Hand Surg Eur Vol 2020;45(10):1078-82.

  13. Straszewski AJ, Lee CS, et al. Temporal relationship of corticosteroid injection and open release for trigger finger and correlation with postoperative deep infections. J Hand Surg Am 2022 Nov;47(11).

  14. 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.

  15. Guler F, Kose O, Ercan EC, et al. Open versus percutaneous release for the treatment of trigger thumb. Orthopedics 2013;36(10):e1290-4.

  16. Bickham R, Carr L, Butterfield J, et al. Current management of trigger digit in rheumatoid arthritis patients: a survey of ASSH members. Hand NY 2022;17(6):1098-1103.

  17. Effendi M, Yuan F, Stern PJ. Not Just Another Trigger Finger. HAND 2025;20(1):43-8.

  18. Federer AE, Baumgartner RE, Cunningham DJ et al. Increased rate of complications following trigger finger release in diabetic patients. Plast Reconstr Surg 2020 Oct;146(4):420e-427.

  19. Baek, Chung, Lee, etc. Factors causing prolonged postoperative symptoms despite absence of complications after A1 pulley release for trigger finger. J Hand Surg Am 2019.

  20. Kosiyatrakul A, Luenam S. Surgical treatment for trigger thumb using a radial approach. J Hand Microsurg 2022;15(5):388-94.

  21. Bayat A, et al. “The pulley system of the thumb: anatomic and biomechanical study.” J Hand Surg Am. 2002:27:628-635.

  22. Lee JY, et al. “A prospective study of bowstringing after A1 pulley release for trigger thumb.  Clin Orthop Surg 2018:10(1):83-89.

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