Trigger Finger Injection

E. J. Mayeaux, Jr, MD, DABFP, FAAFP
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Introduction

Flexor tendon entrapment of the digits is a common condition encountered in primary care practice. This painful condition is known as a trigger finger, and it can produce locking of the finger in the position of flexion. Locking is released by forced extension of the digit, with or without applying pressure to the tendon at the metacarpal or metatarsal head. Release may be associated with a click that can be felt and occasionally heard. Although the fourth finger is most commonly involved, multiple fingers and the thumb also are commonly reported as trigger fingers. Tenderness is common but not always present. Most diagnoses are made from the classic physical findings. 
The problem with a trigger digit is mechanical. A nodular expansion of the tendon can develop, moving with finger motion and catching within the annular A1 pulley over the metacarpophalangeal joint. Alternately, the pulley can become too tight, constricting a normal-sized tendon. Trigger fingers occur in children, usually on the thumb, and probably represent a congenital discrepancy between the size of the tendon and that of the tendon sheath. 
Trigger fingers were historically referred to as stenosing tenosynovitis, but histologic studies fail to document inflammation. Primary disease occurs more often in middle-aged women and is believed to develop from degenerative changes in the flexor tendons and A1 pulleys. Secondary trigger fingers develop from conditions that affect the connective tissues, such as rheumatoid arthritis, diabetes mellitus, and gout. 
Currently, in an uncomplicated case of trigger digit the first-line therapy is still generally agreed to be tendon sheath injection with surgical release of the A1 pulley as second-line treatment. Corticosteroid injection (0.5 mL of triamcinolone [10 mg/mL] mixed with 0.5 to 1.5 mL of 1% lidocaine) can be highly successful, especially early in the course of the disorder. Injection is into the tendon sheath, not into the tendon itself. Steroid therapy may relieve discomfort and produces a cure in up to 85% of individuals with the disorder. If two or three injections fail to result in complete resolution, consultation with a hand surgeon should be sought. 

Equipment

  • Syringes (1 or 3 mL), needles (25 or 27 gauge, 5/8 inch), and alcohol swabs are available from local surgical supply houses or pharmacies.

  • Steroid solutions are available from manufacturers or local pharmacies. Celestone Soluspan (beta-methasone sodium) is produced by Schering-Plough (Kenilworth, NJ, www.schering-plough.com); Aristocort (triamcinolone diacetate) and Aristospan (triamcinolone hexacetonide) can be obtained from Baxter-Lederle (Deerfield, IL, www.baxter.com); and Depo-Medrol (methylprednisolone acetate) is available from Pharmacia Upjohn (Basking Ridge, NJ, www.pharmacia.com).

  • A suggested tray for performing soft-tissue aspirations and injections is listed in Appendix I.

  • Skin preparation recommendations appear in Appendix E.

Indications

  • Locking of flexor tendon of finger or thumb (i.e., flexor tendon entrapment syndrome)

Contraindications (Relative)

  • Failure to respond to multiple injections

  • Uncooperative patient

  • Bleeding diathesis

  • Bacteremia or cellulitis of the palm or thumb

  • Congenital trigger thumb in infants

The Procedure

Step 1

The fourth finger is commonly involved. The condition causes locking of the flexor tendon in a position of flexion. 

Step 2

Place the supine hand flat on a firm surface. The correct insertion site generally is in the palm where the tendon crosses the distal palmar crease. 
  • PITFALL: Novice physicians frequently inject at the base of the digit (i.e., crease where the digit meets the palm). This is well above the metacarpophalangeal joint and above the A1 pulley. The joint can be palpated through the palm; it is at least 1 cm proximal to the crease at the base of the finger.

Step 3

After prepping the area with alcohol, insert the needle at a 45-degree angle with the bevel downward to facilitate injection into the sheath. Insert the needle until the tip reaches the tendon, then back out the needle 1 to 2 mm. Palpate the site with the nondominant (noninjecting) hand to confirm injection into the sheath. 
  • Pearl: The needle may enter the nodule with a distinct grating sensation. This may be verified by asking the patient to gently move the digit, and observing the needle move with the digit. The needle should be withdrawn very carefully until a give-way sensation is felt, indicating that the tip of the needle is in the sheath before injection.

  • PITFALL: Topical ethyl chloride may be used preinjection if the patient is especially fearful of the needle stick.

Step 4

Move the finger immediately after injection to distribute the steroid. A bandage can be applied over the injection site. Nonsteroidal anti-inflammatory medication is prescribed for at least 72 hours to reduce the chance of postinjection flare (i.e., increased pain induced by the steroid crystals). 

Complications

  • Postinjection soreness

  • Vasovagal syncope

  • Local pain

  • Needle breakage

  • Skin infection

  • Short-term increased tenderness

  • Numbness in the digit due to local anesthetic coming into contact with a digital nerve

  • Tendon rupture (rare)

Pediatric Considerations

In infants, a nodule on the flexor pollicis longus tendon can be resected with excellent results. Corticosteroid injections are generally not helpful in pediatric cases of congenital trigger thumb. 

Postprocedure Instructions

Splinting is not used routinely after injection, although a hand splint is used by some providers. A second corticosteroid injection may be performed 3 to 4 weeks later if needed. If two or three injections fail to resolve the problem, consider referring the patient for surgical release. Have the patient watch for signs and symptoms of infection and bleeding. Any suggestion of infection or excessive bleeding should be reported to the physician immediately. 
Inform the patient that some increased tenderness may be felt for a few days until the corticosteroid begins to have a significant effect. They may also have some numbness in the digit if some of the local anesthetic comes into contact with a digital nerve. This should resolve within a matter of hours. If there is prolonged numbness, signs of infection, or an inordinate amount of pain after the procedure, the patient should contact their provider. 
Advise the patient to avoid using the injected fingers strenuously for the next few weeks to minimize the risk of postprocedure tendon rupture. The patient should be continued on a nonsteroidal anti-inflammatory drug or a cyclooxygenase-2 (COX-2) inhibitor if an oral nonsteroidal anti-inflammatory drug is needed. 

Coding Information and Supply Sources

Bibliography

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2008 MAG Mutual Healthcare Solutions, Inc.’s Physicians’ Fee and Coding Guide. Duluth, Georgia. MAG Mutual Healthcare Solutions, Inc. 2007.
 
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