Tag Archive for: mallet finger

High-Yield Summary

• Mallet finger results from disruption of the terminal extensor tendon at the distal interphalangeal (DIP) joint, often with or without an avulsion fracture.
• Non-operative management with continuous DIP extension splinting achieves excellent outcomes in most closed, non-displaced injuries.
• Operative intervention is indicated for large bony fragments involving >30-50% of the articular surface, volar subluxation of the distal phalanx, or open injuries.
• Surgical options vary from percutaneous pinning to open reduction and internal fixation (ORIF), chosen based on fragment size, displacement, and soft tissue status.
• Early recognition and adherence to treatment algorithms optimize functional outcomes and minimize complications such as chronic extensor lag or DIP joint stiffness.

Clinical Fundamentals

Anatomy: The terminal extensor tendon inserts on the dorsal base of the distal phalanx, stabilizing the DIP joint in extension. The extensor mechanism is a delicate balance of tendinous and capsular structures.

Biomechanics: The DIP joint relies on the terminal tendon for extension; disruption leads to unopposed flexion by the flexor digitorum profundus. Bony avulsions compromise joint congruity and stability.

Epidemiology: Mallet finger is common in sports injuries, especially in young adults. It accounts for approximately 9% of hand injuries presenting to emergency departments.

Classification & Diagnosis

Diagnostic Pearls:

• Lateral radiographs with the DIP joint in neutral and slight extension are essential to assess fragment size and displacement.
• Assess for volar subluxation of the distal phalanx, which indicates instability.
• Beware of missed open injuries presenting as small skin lacerations over the DIP joint.

Decision-Making Algorithm

Non-operative Management Criteria:

• Closed injury
• Tendinous mallet or bony fragment <30% of articular surface
• No volar subluxation of distal phalanx
• Patient compliance with continuous splinting

Operative Management Criteria:

• Bony fragment involving >30-50% of articular surface
• Volar subluxation of distal phalanx (joint instability)
• Open injuries or soft tissue interposition preventing reduction
• Failure of non-operative treatment (persistent extensor lag >20° after 6-8 weeks)

Surgical Approach Selection:

• Percutaneous extension block pinning: Preferred for reducible fractures with minimal comminution
• Open reduction and internal fixation (ORIF): Indicated for large fragments, comminution, or soft tissue interposition
• Tendon repair: Reserved for pure tendinous ruptures with significant extensor lag or chronic injuries

Surgical Mastery & Pearls

Stepwise Surgical Technique for Percutaneous Extension Block Pinning:

1. Position the finger in slight hyperextension under fluoroscopy.
2. Insert a Kirschner wire (K-wire) dorsally into the middle phalanx to block extension.
3. Reduce the avulsed fragment by extending the distal phalanx.
4. Insert a second K-wire across the DIP joint to maintain reduction and immobilize the joint.
5. Confirm reduction and hardware placement fluoroscopically.
6. Immobilize the finger in a splint postoperatively for 6 weeks.

Open Reduction and Internal Fixation (ORIF):

• Use a dorsal midline or lateral approach to expose the fragment.
• Carefully protect the extensor tendon and neurovascular bundles.
• Debride interposed tissue and reduce the fragment anatomically.
• Fixation options include mini-screws, tension band wiring, or small plates depending on fragment size.
• Repair the extensor tendon if disrupted.

Intraoperative Red Flags:

• Inability to achieve anatomic reduction due to soft tissue interposition
• Excessive hardware prominence risking skin irritation or tendon attrition
• Unrecognized volar plate or collateral ligament injury compromising joint stability

Technical Tips:

• Maintain continuous DIP extension during splinting or pinning to prevent extensor lag.
• Avoid hyperextension that may cause skin necrosis or joint stiffness.
• Early mobilization after hardware removal is critical to restore range of motion.

Evidence-Based Synthesis

Randomized controlled trials and meta-analyses consistently demonstrate that non-operative splinting yields excellent functional outcomes in tendinous mallet injuries and small avulsion fractures without subluxation. The landmark study by Crawford (1984) established the efficacy of continuous extension splinting with a 90% success rate.

Recent literature emphasizes fragment size and joint subluxation as key predictors of failure with conservative treatment. Studies comparing percutaneous pinning to ORIF show similar functional outcomes, but percutaneous techniques have lower complication rates and shorter operative times.

Controversy persists regarding the threshold fragment size for surgery, with some advocating for >30% involvement while others suggest >50%. Additionally, the role of early surgical intervention in tendinous mallet without fracture remains debated, with limited high-quality evidence.

Open injuries uniformly require surgical management due to infection risk and soft tissue damage, supported by consensus guidelines.

Master Class Pro-Tip

Mastery in mallet finger management hinges on meticulous assessment of joint stability and fragment characteristics. When opting for surgery, prioritize achieving anatomic reduction with minimal soft tissue disruption. Employ percutaneous techniques whenever feasible to reduce morbidity. Vigilantly monitor for subtle volar subluxation on imaging-this is the inflection point where non-operative care fails and surgical intervention becomes mandatory. Finally, patient education on strict splint compliance and early supervised mobilization after immobilization are critical to prevent chronic extensor lag and DIP stiffness, distinguishing a competent surgeon from a master.