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Mallet Finger

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Topic updated on 08/01/16 2:22pm
Introduction
  • A finger deformity caused by disruption of the terminal extensor tendon distal to DIP joint
    • the disruption may be bony or tendinous
  • Epidemiology
    • risk factors
      • usually occur in the work environment or during participation in sports
    • demographics
      • common in young to middle-aged males and older females
    • body location
      • most frequently involves long, ring and small fingers of dominant hand
  • Pathophysiology
    • mechanism of injury
      • traumatic impaction blow
        • usually caused by a traumatic impaction blow (i.e. sudden forced flexion) to the tip of the finger in the extended position.
        • forces the DIP joint into forced flexion
      • dorsal laceration
        • a less common mechanism of injury is a sharp or crushing-type laceration to the dorsal DIP joint
Classification
  • Doyle's Classification 
Doyle's Classification of Mallet Finger Injuries
Type I
 • Closed injury with or without small dorsal avulusion fracture
Type II
 • Open injury (laceration)
Type III
 • Open injury (deep soft tissue abrasion involving loss skin and tendon substance)
Type IV

 • Mallet fracture 
A = distal phalanx physeal injury (pediatrics)
B = fracture fragment involving 20% to 50% of articular surface (adult)
C = fracture fragment >50% of articular surface (adult)


Presentation
  • Symptoms
    • primary symptoms
      • painful and swollen DIP joint following impaction injury to finger 
        •  often in ball sports
  • Physical exam
    • inspection
      • fingertip rest at ~45° of flexion
    • motion
      • lack of active DIP extension
Imaging
  • Radiographs
    • findings
      • usually see bony avulsion of distal phalanx 
      • may be a ligamentous injury with normal bony anatomy
Treatment
  • Nonoperative
    • extension splinting of DIP joint for 6-8 weeks 
      • indications
        • acute soft tissue injury (< than 12 weeks)
        • nondisplaced bony mallet injury
      • technique
        • maintain free movement of the PIP joint  
        • worn for 6-8 weeks
        • volar splinting has less complications than dorsal splinting
        • avoid hyperextension
        • begin progressive flexion exercises at 6 weeks
  • Operative 
    • CRPP vs ORIF post
      • indications
        • absolute indications 
          • volar subluxation of distal phalanx
        • relative indications
          • >50% of articular surface involved
          • >2mm articular gap
    • surgical reconstruction of terminal tendon
      • indications
        • chronic injury (> 12 weeks) with healthy joint
      • outcomes
        • tendon reconstruction has a high complication rate (~ 50%)
    • DIP arthrodesis
      • indications
        • painful, stiff, arthritic DIP joint
    • Swan neck deformity correction
      • indications
        • Swan neck deformity present
Techniques
  • CRPP vs ORIF
    • approach
      • dorsal midline incision
    • fixation
      • simple pin fixation
      • dorsal blocking pin 
  • Surgical reconstruction of terminal tendon
    • repair
      • this may be done with direct repair/tendon advancement, tenodermodesis, or spiral oblique retinacular ligament reconstruction
  • Swan neck deformity correction
    • techniques to correct Swan neck deformity include
      • lateral band tenodesis
      • FDS tenodesis
      • Fowler central slip tenotomy
      • minimal Swan Neck deformities may correct with treatment of the DIP pathology alone
Complications
  • Extensor lag
    • a slight residual extensor lag of < 10° may be present at completion of closed treatment
  • Swan neck deformities  
    • occurs due to
      • attenuation of volar plate and transverse retinacular ligament at PIP joint
      • dorsal subluxation of lateral bands
      • resulting PIP hyperextension
      • contracture of triangular ligament maintains deformity

 

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Qbank (2 Questions)

TAG
(OBQ12.2) A 42-year-old sustains a left finger injury while attempting to catch a baseball for his son. He presents with left, long finger pain and an inability to extend his middle finger at the distal interphalangeal joint. A radiograph after closed reduction and splinting is shown in Figure A. What is the best course of treatment? Topic Review Topic
FIGURES: A          

1. Reduction and pinning
2. Repeat splinting of the distal interphalangeal joint in extension
3. Splinting of the distal and proximal interphalangeal joints in extension
4. Observation
5. Fusion of the distal interphalangeal joint

PREFERRED RESPONSE ▶
TAG
(OBQ12.85) A 27-year-old male presents with finger pain 2 days after suffering an injury while playing basketball. Physical exam shows swelling of the distal interphalangeal joint with no evidence of open injury. A radiograph is shown in Figure A. Which of the following is the most appropriate treatment at this time? Topic Review Topic
FIGURES: A          

1. Extension splinting of DIP joint for 6-8 weeks
2. Closed reduction and percutaneous pinning
3. Open reduction and internal fixation
4. DIP arthrodesis
5. Swan neck deformity correction

PREFERRED RESPONSE ▶



Cases

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