Updated: 9/25/2018

Seymour Fracture

Review Topic
  • Displaced distal phalangeal physeal fracture with an associated nailbed injury
  • Epidemiology
    • incidence
      • 20% to 30% of phalangeal fractures involve the physis in children
    • body location
      • middle finger injury is most common
      • type of the distal phalangeal physeal fracture:
        • metaphyseal fractures 1 to 2 mm distal to the epiphyseal plate
        • Salter-Harris I fractures
        • Salter-Harris II fractures
      • type of nailbed injury:
        • nailbed laceration
        • nail plate subluxation
        • interposition of soft tissue at fracture site (usually germinal matrix)
  • Pathophysiology
    • mechanism of injury
      • direct trauma or crush injury (e.g. caught in door, heavy object or sport)
    • pathoanatomy
      • similar mechanism to mallet finger in adults
      • injury causes flexed posturing of the distal phalanx
      • deformity results from an imbalance between the flexor and the extensor tendons at the level of the fracture
      • imbalance occurs due to different insertion sites of flexor and extensor tendons
        • extensor tendon inserts into the epiphysis of the distal phalanx
        • flexor tendon inserts into metaphysis of the distal phalanx
      • widened physis likely to have interposed tissue in the fracture site 
  • Prognosis
    • operative intervention is warranted to ensure that there is no interposed tissue in the fracture site
    • failure to recognize injury may result in:
      • nailplate deformity
      • physeal arrest
      • chronic osteomyelitis
  • Physical exam
    • apparent mallet deformity
    • echymosis and swelling
    • nail plate lying superficial to the eponychial fold
  • Radiographs
    • recommended views
      • PA
        • may appear normal
      • lateral
    • findings
      • widened physis or displacement between epiphysis/metaphysis
      • flexion deformity at fracture site 
        • seen on lateral view
Differential Diagnosis
  • Mallet finger
    • pediatric mallet finger is usually osseous avulsion (SH III and SH IV)
    • mallet finger fracture line enters DIPJ, while Seymour fracture line traverses physis (does not enter DIPJ)
  • Nonoperative
    • closed reduction and splinting
      • indications
        • minimally displaced, closed fracture
        • no interposition of soft tissue at fracture site
  • Operative
    • closed reduction and pinning across DIPJ 
      • indications
        • displaced, closed fracture
        • no interposition of soft tissue at fracture site
    • antibiotics, open reduction and pinning across DIPJ, nailbed repair
      • open management has fewer complications than closed management
      • indications
        • open fracture
      • technique
        • hyperflexion of the digit will permit removal of the interposed soft tissue from the fracture site
        • thorough irrigation and debridement
        • anatomical reduction and retrograde k-wire fixation crossing the fracture site and DIP joint
        • nailbed injury repair
  • Nail dystrophy
  • Growth disturbance of the distal phalanx and nail
  • Secondary fracture displacement 
  • Chronic osteomyelitis (failure to treat as open fracture)
  • Flexion deformity

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