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Updated: Mar 4 2024

Distal Femoral Physeal Fractures - Pediatric

  • summary
    • Distal Femoral Physeal Fractures are common fractures in the pediatric population that result from direct trauma in children with open physes. 
    • Diagnosis is confirmed with plain radiographs of the femur and knee. 
    • Treatment is usually operative with closed reduction and percutaneous fixation followed by casting. These fractures are at high risk for the development of future growth arrest. 
  • Epidemiology
    • Demographics
      • occur in patients with open growth plates
      • must be considered in patients with open physes to avoid misdiagnosis with collateral ligament injury
  • Pathophysiology
    • Mechanism of injury
      • often the result of direct trauma with some degree of rotation
      • most commonly a valgus-type force or a hyperextension force
    • Most commonly Salter-Harris II fracture
      • physis fails on the tension side
      • metaphysis fails on the compression side, creating a Thurston-Holland fragment
      • injury to physis occurs at the zone of hypertrophy
  • Anatomy
    • Osteology
      • formed from a single ossific nucleus that is present at birth and is the first epiphysis in the body to ossify
    • Muscles
      • both heads of the gastrocnemius and plantaris muscles originate just proximal to the physis
        • leads to flexion of the distal fracture fragment when fracture line is distal to muscle insertion
    • Ligament
      • collateral ligaments attach distal to the physis at the level of the epiphysis
        • stress places tension on the collaterals which transfer force to the physis
      • ACL and PCL attach to epiphysis at the intercondylar notch and may be injured
    • Blood Supply
      • femoral artery travels through the adductor canal medially above the metaphysis and courses in the popliteal space
      • popliteal artery is directly posterior to distal femur
        • trifurcates at this level
        • due to poor collateral circulation, popliteal artery injury may result in loss of lower limb viability
    • Physeal considerations of the knee
      • general assumptions
        • leg growth continues until
          • 16 yrs in boys
          • 14 yrs in girls
      • growth contribution
        • leg grows 23 mm/year, with most of that coming from the knee (in contrast to upper extremity where most of growth is away from the elbow)
          • proximal femur - 3 mm / yr (1/8 in)
          • distal femur - 9 mm / yr (3/8 in)
          • proximal tibia - 6 mm / yr (1/4 in)
          • distal tibia - 5 mm / yr (3/16 in)
  • Presentation
    • History
      • history of significant trauma
    • Symptoms
      • pain with inability to bend knee
      • unable to bear weight
    • Physical exam
      • pain and swelling
      • often in flexed position due to hamstring muscle spasm
      • tenderness along the physis in the presence of a knee effusion
      • may see varus or valgus knee instability on exam
      • swelling in the popliteal space may be a sign of vascular injury or disruption
  • Imaging
    • Radiographs
      • recommended views
        • AP
        • lateral
        • oblique
        • stress radiographs to look for physis opening if there was suspicion of physeal injury have fallen out of favor due to risk of physeal damage, patient discomfort, and possible need for sedation
          • MRI or ultrasound have replaced stress radiographs in this setting
      • indications
        • at presentation
        • close follow up with repeat x-rays if inital radiographs not definitive and treating as a possible Salter I fracture
      • findings
        • physeal widening
          • normal 3-5mm
        • direction of displacement suggestive of mechanism of injury
          • anterior displacement due to hyperextension
          • posterior displacement due to hyperflexion
          • medial displacement due to valgus
          • lateral displacement due to varus
    • MRI
      • indications
        • diagnostic modality of choice to confirm physeal fracture
    • Ultrasound
      • indications
        • can help confirm physeal fracture
    • CT
      • may be necessary for evaluation of intra-articular extension and to define fracture fragments to plan fixation
    • Angiography
      • occasionally necessary to evaluate for a vascular injury in the case of abnormal ABI (<0.9)
      • may be necessary in fractures with wide displacement and posterior spiked fragments
  • Treatment
    • Nonoperative
      • long leg casting
        • indications
          • nondisplaced fractures
        • treated for 4-6 weeks
        • close clinical follow up is mandatory
    • Operative
      • closed reduction and percutaneous fixation followed by casting
        • indications
          • majority of cases
          • displaced Salter-Harris I or II fractures
          • displaced fractures successfully reduced with closed methods typically should still be secured with fixation as fracture pattern is unstable
          • some Salter-Harris III or IV injuries if anatomic reduction is achieved
        • postoperatively follow closely to monitor for deformity
      • ORIF
        • indications
          • Salter-Harris III and IV with weight-bearing articular involvement
          • irreducible SHI and SHII fractures
            • irreducible type II fractures are most often due to interposed periosteum on the tension side of fracture
  • Techniques
    • Closed reduction and percutaneous fixation
      • reduction
        • avoid multiple attempts at reduction
        • reduction maneuver consists of 90% traction and 10% manipulation
      • fixation
        • if physis must be crossed (SH I and SH II with small Thurston-Holland fragments)
          • use smooth K-wires
          • remove 3-6 weeks after surgery
        • SH II fracture with large enough metaphyseal fragment should be fixed with lag screws across the metaphyseal segment
    • Open Reduction Internal Fixation
      • approach
        • incision over the displaced physis to remove interposed periosteum is necessary.
      • fixation should avoid the physis if possible
      • postoperative
        • usually add post-operative immobilization
  • Complications
    • Limb length discrepancy or angular deformity(most common)
      • results from physeal disturbance
      • limb length inequality of >2 cm in one third of cases
      • correlates with fracture pattern
        • 36% of SH 1 fractures
        • 58% in SH 2 fractures
        • 49% in SH 3 fractures
        • 64% in SH 4 fractures
      • minimize with
        • anatomic physeal alignment (critical)
        • close follow up following nonoperative or operative treatment
      • treatment
        • no treatment necessary when predicted final leg length discrepancy <2 cm and no significant angulation
        • indicated for discrepancy between 2-6 cm
          • epiphysiodesis of the contralateral distal femur +/- proximal tibia
        • physeal bridge excision
          • indication
            • physeal bar of <50% and
            • ≥ 2 years or 2.5 cm of growth remaining
    • Septic arthritis
      • Intra-articular pins have a risk of septic arthritis
    • Popliteal artery injury and compartment syndrome
      • rare, most common with anterior displacement of epiphysis or a posterior spike at the fracture site
  • Prognosis
    • Physeal arrest
      • 30-50% rate of physeal arrest that often leads to growth disturbance and deformity
        • counsel parents of poor prognosis associated with this fracture pattern
        • an increased incidence of complications have been associated with
          • 218554Salter-Harris classification type (I and V associated with non-angular deformities)
          • fracture displacement
          • surgical hardware invading the physis
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