Mallet Finger: Diagnosis and Management
Suspected Diagnosis
This is a mallet finger injury—an extensor tendon rupture at the distal interphalangeal (DIP) joint, not the MCP or PIP joint as suggested in the expanded question. The inability to actively extend the fingertip after an axial loading injury (grabbing a jersey) is pathognomonic for this zone I extensor tendon injury 1, 2.
Key Clinical Features
- Mechanism: Axial load applied to an extended fingertip causing forced flexion of the DIP joint, resulting in either tendon rupture or bony avulsion 1
- Presentation: Loss of active DIP joint extension with a characteristic "drooping" fingertip posture 2
- Physical examination: The patient cannot actively extend the DIP joint, though passive extension remains intact 1
Initial Imaging
Obtain standard radiographs of the affected finger immediately to differentiate between tendinous (soft tissue) and bony mallet finger, as this distinction affects splinting duration 1, 3.
- Three views are essential to identify any avulsion fracture at the base of the distal phalanx and assess for DIP joint subluxation 1
- Radiographs help classify the injury using Tubiana's classification, which guides treatment decisions 1
- Advanced imaging (MRI or CT) is not indicated for routine mallet finger diagnosis 4, 2
Management Algorithm
Non-Operative Treatment (First-Line for Nearly All Cases)
Immediate continuous splinting of the DIP joint in extension (or slight hyperextension for tendinous injuries) is the definitive treatment 5, 1, 6, 3.
Splinting Protocol Based on Injury Type:
For Tendinous (Soft Tissue) Mallet Finger:
- Duration: 6-8 weeks of continuous full-time splinting, though some evidence supports up to 12 weeks for optimal outcomes 5, 6, 3
- Position: DIP joint in slight hyperextension 1
- Night splinting: Additional 2-4 weeks of nighttime-only splinting after the full-time period 5, 3
For Bony Mallet Finger (Avulsion Fracture):
- Duration: 6 weeks of continuous splinting 3
- Position: DIP joint in neutral/straight position (not hyperextension) 1
- Night splinting: Additional 2 weeks after full-time period 3
Splint Options:
- Stack splint or dorsal glued splint are both effective 5, 3
- Dorsal glued splints (adhered to the nail plate) may improve compliance by preserving digital pulp sensation and function 3
- Critical requirement: Uninterrupted immobilization—even brief removal can restart the healing timeline 6
Surgical Indications (Rare)
Surgery is indicated only for:
- Stage IV injuries: Irreducible DIP joint subluxation despite splinting 1
- Large bony fragments (>30-40% of articular surface) with persistent subluxation 1
- Failed conservative treatment after a complete course of appropriate splinting 6
Preferred surgical approach when needed: Transarticular Kirschner wire fixation for 6-8 weeks 6, 2
Critical Management Pitfalls
Common Errors to Avoid:
- Never convert a closed injury to open surgically unless absolutely necessary—complication rates are unacceptably high with primary surgical repair 6, 2
- Do not interrupt splinting even briefly during the immobilization period, as this restarts the healing clock 6
- Avoid heat application—use ice/cold therapy for initial pain and swelling control 4
- Do not attempt to straighten the finger manually before splinting 4
Initial First Aid (Before Definitive Splinting):
- Apply ice-water mixture (not ice alone) for 10-20 minutes with a thin towel barrier to reduce swelling 4
- Splint the finger in the position found until proper evaluation 4
- Refer promptly for definitive splinting—treatment can be delayed somewhat and still be effective, though earlier is better 6
Expected Outcomes
With appropriate conservative treatment, expect:
- Mean residual extension lag of 2-3 degrees at final follow-up 5, 3
- 56-81% excellent/good results by Crawford criteria 5, 3
- Maintained DIP flexion averaging 68 degrees 5
- Low complication rates (6-14%) with proper technique 3
Untreated mallet finger leads to: swan-neck deformity and DIP joint osteoarthritis 1, 2