Mallet Finger Fixation

Mallet finger occurs due to disruption of the extensor tendon at the distal interphalangeal (DIP) joint, often with or without an associated avulsion fracture. Surgical fixation is indicated when non-operative treatment fails or when there is a large fracture fragment affecting joint stability.

1. Indications

Surgical fixation is recommended in the following cases:

Bony mallet finger with >30-50% articular surface involvement.
DIP joint subluxation due to avulsion fracture.
Failed nonoperative treatment after 6-8 weeks of splinting.
Chronic mallet finger causing persistent pain and dysfunction.
Irreducible mallet injuries due to soft tissue interposition.

2. Contraindications

Severe osteoporosis or poor bone quality making fixation difficult.
Active infection at the injury site.
Advanced arthritis or chronic deformity unresponsive to correction.
Non-compliant patients unable to adhere to postoperative care.
Poor vascularity (e.g., severe diabetes or smoking-related vascular disease).

3. Preoperative Preparation

Clinical Examination: Assess DIP extension lag, swelling, and tenderness.
Imaging: X-rays (AP, lateral, oblique) to evaluate fracture displacement and articular involvement.
Patient Counseling: Explain surgical options, risks (infection, stiffness), and postoperative rehabilitation.
Preoperative Antibiotics: A single dose of cefazolin (1g IV) or clindamycin (600mg IV) for penicillin-allergic patients.

4. Special Instruments

Kirschner wires (K-wires) (0.9–1.2 mm) for percutaneous fixation.
Mini C-arm fluoroscopy for real-time intraoperative imaging.
Needle driver and forceps for precise pin placement.
Fine-point drill or pin driver for smooth wire insertion.
Wire cutter to trim excess K-wire length.
Towel clips for temporary reduction and stabilization.

5. Position and Anesthesia

Patient Positioning

Supine with the hand placed on a radiolucent hand table.
A finger tourniquet (rubber band or Penrose drain) may be used to minimize bleeding.
Ensure C-arm access for fluoroscopic imaging.

Anesthesia Options

Digital block (2% lidocaine or 0.5% bupivacaine) for isolated cases.
Wrist block if multiple fingers require intervention.
General anesthesia if associated complex hand trauma is present.

6. Operative Technique & Approach

Step 1: Preparation and Reduction

Cleanse the hand with antiseptic solution (chlorhexidine or povidone-iodine).
Drape the finger to maintain a sterile field.
Gently extend the DIP joint to align the fracture or tendon avulsion.

Step 2: K-Wire Fixation (Percutaneous Approach)

Under fluoroscopic guidance, insert a 0.9–1.2 mm K-wire dorsally through the distal phalanx to maintain DIP extension.
Alternatively, cross two divergent K-wires for better rotational stability.
Ensure the wires do not penetrate the PIP joint.

Alternative Techniques

Extension Block Pinning (for bony mallet fractures)
- Insert a K-wire transversely across the DIP joint to act as an extension block.
- Reduce the fracture fragment and insert a second retrograde K-wire to fix the distal fragment.
- Confirm reduction under fluoroscopy.
Suture Repair (for tendinous mallet injuries)
- Use non-absorbable suture (3-0 Prolene or Ethibond) through small bone tunnels to secure the extensor tendon.

Step 3: Final Fixation & Closure

Confirm alignment and stability on fluoroscopy.
Trim excess K-wire length and bend it to prevent migration.
Apply antibiotic ointment and a sterile dressing.

7. Tips and Pearls

Use a 22G hypodermic needle to guide percutaneous pin placement.
Overcorrecting extension slightly prevents residual extensor lag.
If using extension block pinning, ensure the block pin doesn’t impinge on motion.
Avoid multiple drilling attempts to reduce thermal necrosis.
For tendinous injuries, consider using a pull-out suture technique for better fixation.

8. What to Avoid

Inaccurate K-wire placement leading to malalignment.
Over-penetration of the wire into the PIP joint, restricting motion.
Leaving wires too long, increasing the risk of skin irritation and infection.
Failure to check for DIP subluxation after fixation.
Not counseling patients on stiffness risks associated with prolonged immobilization.

9. Postoperative Care Issues

Splinting: Maintain DIP joint in full extension with a splint (stack splint or custom thermoplastic splint) for 6 weeks.
Pin Removal: K-wires are removed at 4-6 weeks under local anesthesia.
Physical Therapy: Gradual DIP motion is initiated after wire removal to prevent stiffness.
Wound Care: Regular dressing changes and pin site care to prevent infection.
Complication Monitoring: Watch for K-wire loosening, extensor lag, infection, or malunion.