What is the recommended procedural technique for a trigger finger injection over the 3rd proximal interphalangeal (PIP) joint?

Procedural Technique for Trigger Finger Injection Over 3rd PIP Joint

The recommended procedural technique for trigger finger injection over the 3rd proximal interphalangeal (PIP) joint involves using triamcinolone acetonide 20 mg without local anesthetic, using aseptic technique, and avoiding joint overuse for 24 hours post-injection. 1

Preparation and Materials

• Triamcinolone acetonide 20 mg (1 mL)
• 1 mL normal saline (instead of local anesthetic)
• 25-27 gauge needle
• Alcohol swabs or chlorhexidine for skin preparation
• Sterile gloves
• Sterile gauze
• Band-aid

Step-by-Step Injection Technique

1. Patient Positioning

   • Position the patient with hand resting palm-up on a flat surface
   • Place a small rolled towel under the wrist for support and slight extension

2. Site Identification

   • Locate the A1 pulley at the level of the metacarpophalangeal (MCP) joint crease on the palmar aspect
   • Identify the nodule or area of maximum tenderness over the flexor tendon
   • Mark the injection site with a skin marker if needed

3. Aseptic Preparation

   • Perform thorough hand hygiene
   • Don sterile gloves
   • Clean the injection site with alcohol or chlorhexidine in a circular motion from center outward
   • Allow antiseptic to dry completely

4. Medication Preparation

   • Draw up 1 mL (40 mg) of triamcinolone acetonide
   • Add 1 mL of normal saline (not local anesthetic, as evidence shows increased pain with lidocaine) 2

5. Injection Technique

   • Hold the patient's finger in slight extension
   • Insert the needle at a 45-degree angle to the skin, with the bevel up
   • Advance the needle until it contacts the tendon sheath
   • Withdraw slightly to ensure the needle is not within the tendon
   • Inject the solution slowly into the flexor tendon sheath
   • If resistance is felt, reposition the needle slightly
   • Distribute the medication along the tendon sheath

6. Post-Injection Care

   • Apply gentle pressure with sterile gauze
   • Apply a band-aid over the injection site
   • Advise the patient to avoid overuse of the injected finger for 24 hours 3

Important Considerations

Dosage Selection

• 20 mg of triamcinolone acetonide has been shown to be more effective than lower doses (5 mg or 10 mg), with 79% effectiveness at 6 months compared to 52-62% with lower doses 1

Anesthetic Considerations

• Omitting local anesthetic results in less injection-associated pain compared to including lidocaine with epinephrine 2
• If patient anxiety is high, consider topical anesthetic prior to injection

Special Populations and Precautions

• For diabetic patients, warn about potential transient hyperglycemia for 1-3 days post-injection 3
• Avoid injection if there are signs of infection at the injection site
• Limit to no more than 3-4 injections per year in the same joint 3

Post-Injection Management

• Consider finger splinting in combination with injection for cases with PIP joint flexion contracture 4
• Functional DIP joint splinting may be beneficial for patients who need to return to work immediately 5

Potential Complications

• Pain at injection site
• Skin depigmentation
• Tendon rupture (rare)
• Infection (extremely rare, 0.035%)
• Nerve damage (rare)

By following this systematic approach, you can effectively administer trigger finger injections over the 3rd PIP joint while minimizing complications and maximizing therapeutic benefit.