Mallet Finger

Other Names

• Extensor Avulsion Fracture
• Distal Extensor Tendon Rupture
• Mallet Finger
• Terminal Extensor Tendon Injury

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Background

Mallet finger mechanism of injury

Soft tissue vs bony mallet finger

• This page describes mallet finger, a distal extensor tendon injury characterized by an inability to extend DIPJ

History

• Needs to be updated

Epidemiology

• Epidemiology is not well described
• There is a male predominance in the first 3 decades of life
• By the 6th decade, the incidence is roughly the same between men and women
• One study estimated 9.3% of soft tissue injuries and 9.9 cases per 100,000 population per year

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Introduction

General

• Named for flexion deformity which resembles a mallet or hammer
• Occurs when distal phalanx is forced into flexion while being actively extended
• May or may not include an osseus avulsion fracture
• Digits 3-5 most commonly affected (need reference)
• Results in loss of extension at the level of the distal interphalangeal joint
• The vast majority can be treated non-surgically with immobilization in extension

Etiology

• Acute, axial trauma
• Laceration
• Rarely, hyperextension of DIPJ

Mechanism of Injury

• Forceful flexion or hyperextension of an extended distal phalanx
  • Causing extensor tendon disruption
  • Either isolated or in combination with a distal phalanx avulsion fracture

Anatomy of the Extensor Expansion of the Hand

• Specialized connective tissue structure that supports extensor tendon insertion onto the phalanges
• Acts to balance the large number of muscles acting on the fingers
• Triangular shape, begins at the level of the metacarpophalangeal joint
• Formed from the extensor digitorum (fingers) tendons creating an extensor hood
• Divides into central slip (middle phalanx) and two lateral bands (distal phalanx)

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Risk Factors

• Ball sports where ball hits fingertip of extended finger
• Young middle aged males
• Older females

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Differential Diagnosis

• Fractures
  • Phalanx Fractures (Hand)
  • Metacarpal Fractures
    • Boxer's Fracture
    • Rolando Fracture
    • Bennett Fracture
• Dislocations
  • Metacarpophalangeal Joint Dislocation
  • Proximal Interphalangeal Joint Dislocation
  • Distal Interphalangeal Joint Dislocation
• Tendon Injuries
  • Extensor Tendon Injuries (Hand)
  • Central Slip Extensor Tendon Injury
  • Flexor Tendon Injuries (Hand)
  • Boutonniere Deformity
  • Swan Neck Deformity
  • Jersey Finger
  • Mallet Finger
  • Trigger Finger (Stenosing Tenosynovitis)
• Ligament Injuries
  • Gamekeeper’s Thumb
  • Volar Plate Avulsion Injury
• Neuropathies
  • Wartenbergs Syndrome
  • Carpal Tunnel Syndrome
  • Posterior Interosseus Nerve Syndrome
• Arthropathies
  • Carpometacarpal Arthritis
• Pediatric Considerations
  • Proximal Phalanx Avulsion Fracture (Thumb)
  • Middle and Distal Phalanx Avulsion Fracture
• Other
  • Nailbed Injuries

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Clinical Features

Clinical example of Elson's Test

History

• Primarily a clinical diagnosis
• Patient may not always describe forced flexion
• Patient typically reports pain, flexion deformity, difficulty using finger

Physical Exam: Physical Examination Hand

• Fingertip typically resting at 45°
• Characterized by inability to extend DIPJ
• There may also be swelling and bruising

Special Tests

• Elson's Test: Evaluate extension of DIPJ in isolation

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Evaluation

Avulsion fracture of the distal phalanx of the 5th digit

Radiographs

• Standard Radiographs Hand
  • Typically normal

Additional Imaging

• Role of US, MRI unclear

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Classification

Doyle classification

Doyle’s Classification of Mallet Finger Injuries

• Grade 1: Closed injury, with or without small dorsal avulsion fracture
• Grade 2: Open injury (laceration)
• Grade 3: Open injury (deep abrasion involving skin and tendon)
• Grade 4: Mallet fracture
  • A: distal phalanx physeal fracture (pediatrics)
  • B: fracture fragment involving 20-50% articular surface
  • C: fracture fragment involving >50% articular surface

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Management

Stack Splint

Nonoperative

• Indications:
  • Acute <12 weeks
  • Closed
  • <1/3 of articular surface
  • No associated DIP subluxation
• Typically immobilize DIPJ only in extension splint
  • Including Stack Splint, thermoplastic splint, aluminum-foam splint
  • Duration usually 6-8 weeks

Operative

• Indications:
  • >1/3 articular surface involved
  • Joint subluxation
  • Open fracture
• Technique
  • Typically immobilized with a K-wire

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Rehabilitation and Return to Play

Rehabilitation

• Needs to be updated

Return to Play

• Splint typically work for 6-8 weeks

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Prognosis and Complications

Swan neck deformity in a patient with rheumatoid arthritis

Prognosis

• Needs be updated

Complications

• Swan Neck Deformity
• Extensor lag

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See Also

Internal

• Hand and Wrist Anatomy (Main)
• Finger Pain (Main)
• Hand Pain (Main)

External

• Sports Med Review Hand Pain: https://www.sportsmedreview.com/by-joint/hand/

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