Description

Pediatric bone consists of four segments: The diaphysis or shaft, the metaphysis (the widest region, where bone growth occurs), the physis or growth place, the epiphysis (distal to the growth plate, site of secondary ossification)

Fractures through the physis account for 21-30% of pediatric long bone fractures; 30% leading to a growth disturbance:

• Most frequently seen in the distal radius and ulna, distal tibia and fibula, and the phalanges
• In children, more common than ligamentous injuries:
  • Tensile strength of pediatric bone is less than adjacent ligaments
  • Physis is weakest part of pediatric bone
  • Similar injury in an adult usually results in a sprain
• Most common during peak growth:
  • Females: Age 9-12
  • Males: Age 12-15
  • Much less common in infancy and early childhood because epiphysis is not ossified and acts as a shock absorber
• Twice as common in males because female bones mature earlier
• Salter-Harris (SH) classification: Simplest and most commonly used classification system:
  • The grade of the SH fracture correlates with the likelihood of subsequent growth disturbance, with a higher SH grade corresponding to a worse prognosis
  • A helpful mnemonic for remembering the types is SALTER:
    • Straight: Type I
    • Above: Type II
    • beLow: Type III
    • Through: Type IV
    • Erasure: Type V
  • SH type I:
    • Transverse fracture line confined to physis
    • Complete epiphyseal separation from metaphysis through the physis
    • If periosteum remains intact, epiphysis will not displace
    • Clinical diagnosis made with focal tenderness over the physis
    • Most common example is SCFE
    • Growth disturbance is rare
  • SH type II:
    • Most common type; accounts for ∼80% of physeal fracture patterns
    • Fracture propagates along physis, and fragment from metaphysis accompanies the displaced epiphysis (Thurston Holland sign)
    • Periosteum torn opposite metaphyseal fragment
    • Growth is rarely disturbed
  • SH type III:
    • Rare
    • Fracture through a portion of physis extending through the epiphysis
    • Distal tibia most commonly affected
    • If displaced, requires reduction to maintain anatomic alignment
    • Growth disturbance may occur despite anatomic reduction because blood supply can be affected
  • SH type IV:
    • Fracture originates at articular surface
    • Extends through physis and into both metaphysis and epiphysis
    • Distal humerus most commonly affected
    • Also has Thurston Holland fragment
    • Anatomic reduction essential and displaced fractures require ORIF
    • Growth arrest is common even with optimal treatment
  • SH type V:
    • Results from severe crush injury to physis
    • No immediately visible radiographic alteration so almost impossible to diagnose initially
    • Often found in retrospect
    • Compression forces lead to physeal injury and inevitable growth disturbances
• Ogden modified the SH system to include injuries to the surrounding anatomy - periosteum, perichondrium, and zone of Ranvier:
  • Ogden types I-V are similar to SH types I-V
  • Ogden type VI: Involves the peripheral perichondrium including the zone of Ranvier
  • Ogden type VII: Involves epiphysis only
  • Ogden type VIII: Involves metaphysis and can result in physeal ischemia
  • Ogden type IX: Involves the periosteum of the diaphysis and metaphysis with possible disruption of membranous growth and ossification
• Peterson classification system, 1994:
  • Result of a 10-yr retrospective study showed that 16% of physeal injuries could not be classified by the SH system
  • Classification includes 6 fracture patterns, including 2 that were not described by the SH or Ogden classification systems:
    • Peterson type I - Transverse fracture through the metaphysis with 1 or more longitudinal extensions into the physis. This was actually the most common fracture pattern found
    • Peterson type VI - A part of the epiphysis, physis, and metaphysis are missing due to an open injury, classically by a lawnmower. Associated with severe growth disturbance

Etiology

• Competitive and recreational injuries
• Traumatic injuries
• Child abuse
• Extreme cold
• Radiation injury
• Genetic, neurologic, and metabolic disease