Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Trigger Finger

Basics

Description
  • A trigger finger is a manifestation of stenosing tenosynovitis that results in painful catching of the involved flexor tendon as the patient flexes and extends the digit.
  • As the affected digit is slowly flexed, it snaps or triggers into a flexed position.
  • Once the digit triggers, extension is difficult and, occasionally, must be obtained manually.
Pregnancy Considerations
  • Incidence in pregnant females may be higher than that in the general population.
  • Treat with corticosteroid injection for temporary triggering relief because it likely will resolve or not recur.
Epidemiology
  • Affected digits:
    • In the adult, all digits, but most commonly, the thumb, ring, and middle fingers
    • In the child, primarily the thumb
  • Children (congenital type) and middle-aged patients predominate.
  • The adult variety of trigger finger is more common in females than in males.
Incidence
The lifetime incidence in nondiabetic adults >30 years old is reported to be 2.2% and that in adults with insulin-dependent diabetes mellitus is up to 10%.
Risk Factors
  • Rheumatoid arthritis
  • Increased age
  • Diabetes mellitus
Etiology
  • A nodule usually develops on the flexor tendon, most likely in response to abrasion of the tendon in the tendon sheath.
  • The nodule then impinges on one of the rings of fibrous tissue encircling the flexor tendon sheath known as the A1 pulley; the result is “triggering when the digit is extended (Fig. 1).
  • This problem is self-perpetuating because the irritation from triggering prevents a decrease in the swelling.
  • In the pediatric population (<2 years old), a congenital narrowing of the tendon sheath or a nodular thickening in the tendon (Notta node) may be present, resulting in congenital trigger digit, most commonly the thumb.
Associated Conditions
  • In congenital trigger digit, an association with trisomy 13 exists.
  • In the adult patient, other disorders related to tenosynovitis, such as de Quervain tenosynovitis and CTS, may be present.
  • Systemic disorders that cause connective tissue abnormalities, such as diabetes, gout, and rheumatoid arthritis, also may be present.
Diagnosis
Signs and Symptoms
  • Sign: A nodule in the palm of the hand, just distal to the distal palmar crease
  • Symptom: Painful locking or snapping of the digit into a flexed position with flexion
Physical Exam
  • By gently palpating the flexor tendon sheath of the affected digit in the region of the distal palmar crease and then having the patient flex the digit, the offending nodule and/or triggering sometimes may be palpated.
  • In children <2 years old, 30% have bilateral involvement.
Tests
Lab
No serum laboratory tests aid in this diagnosis.
Imaging
Imaging studies usually are not necessary because trigger finger is a clinical diagnosis.
Fig. 1. In trigger finger, a nodule in the tendon sheath prevents it from sliding under the pulley. The finger does not extend.
Differential Diagnosis
  • Tendon rupture
  • Contracted (ankylosed) joints
  • Congenital clasped thumb
  • Absent extensor
  • Tumor of tendon sheath
  • Loose body in the MCP joint
Treatment
General Measures
  • Triggering may unlock with rest.
  • In children:
    • <6 months old: 30% resolve spontaneously.
    • 6-30 months old: Only 12% resolve spontaneously.
    • Many require surgical intervention, which is recommended before 4 years of age to prevent permanent contracture of the IP joint
  • In adults: Corticosteroid injection is 1st line of treatment.
  • When nonoperative therapy fails, surgical incision of the A1 pulley has a 98% cure rate.
  • No restrictions are placed on activity after injection.
Special Therapy
Physical Therapy
None is needed.
Medication
First Line
  • In adults, treatment commences with injection of the tendon sheath (but not the tendon) with lidocaine and cortisone in the region of the A1 pulley.
    • A single injection results in a 44-93% success rate.
    • The use of >3 injections has a 77-88% success rate.
Surgery
  • A small transverse or oblique incision is made in the region of the A1 pulley (just distal to the distal transverse palmar crease) and overlying the affected flexor tendon.
  • The A1 pulley is incised.
  • After surgical release, the hand is bandaged for several days.
  • Activity is resumed gradually.

P.473
Follow-up
Prognosis
The prognosis is good.
Complications
  • Errant injections may result in damage to the tendon or digital nerves and vasculature, but these complications are rare.
  • Surgical risks include digital nerve laceration, tendon rupture, infection, and reflex sympathetic dystrophy.
Patient Monitoring
None is necessary after surgical release.
Miscellaneous
Codes
ICD9-CM
  • 727.03 Trigger finger, acquired
  • 756.89 Congenital
Patient Teaching
Patients are advised to have surgical release for recurrent symptoms.
FAQ
Q: What is the initial treatment for a trigger digit?
A: Most trigger digits in adults can be treated successfully with corticosteroid injection.
Q: Is trigger digit associated with any medical comorbidities, and does this affect prognosis?
A: Secondary trigger digit can be associated with diabetes mellitus, gout, renal disease, rheumatoid arthritis, and other rheumatic diseases. It is associated with a worse prognosis after nonoperative or operative management.

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