Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Hip Fracture in the Child

Basics
Description
  • Fracture of the femoral neck, in the intertrochanteric or subtrochanteric region
  • Classification: Delbet system as popularized by Colonna:
    • Type I
      • Transphyseal separation (femoral head separates from neck through the growth plate)
      • Can be nondisplaced (widened physis), displaced, or dislocated
      • Least common type
      • Occurs in young children
      • Many patients have dislocation of the femoral head from the acetabulum.
    • Type II:
      • Transcervical
    • Type III:
      • Cervicotrochanteric
    • Type IV:
      • Intertrochanteric
  • Initial displacement seems to affect the risk of osteonecrosis most.
  • Anatomy:
    • Blood supply:
      • At birth, the blood supply to the femoral head travels through the metaphyseal vessels traversing the neck, deriving from the medial and lateral femoral circumflex arteries.
      • The growth plate of the proximal femur prevents these vessels from penetrating the femoral head.
      • By 4 years of age, the contribution by the metaphyseal blood supply is negligible, and the medial femoral circumflex artery provides the major blood supply to the head.
      • Capsulotomy of the hip does not damage the femoral head’s blood supply unless the procedure violates the intertrochanteric notch or damages the posterosuperior or posteroinferior vessels along the femoral neck.
      • The ligamentum teres contributes only a small percentage of the blood supply to the femoral head.
    • Bone:
      • ~1/2 of pediatric hip fractures are nondisplaced.
      • If the fracture is displaced, it is likely to be unstable.
Epidemiology
Incidence
This injury accounts for <1% of all pediatric fractures, far less than the percentage in adults because the bone is so strong.
 
Etiology
  • 75% of pediatric hip fractures are caused by severe trauma and high-velocity injuries (e.g., motor vehicle accidents, falls).
  • The remainder result from some underlying pathologic process (e.g., fracture through a unicameral bone cyst, aneurysmal bone cyst, or fibrous dysplasia) or child abuse.
Associated Conditions
  • Infants:
    • Suspect child abuse.
    • If the injury is a result of an automobile accident, look for associated injuries.
  • Children:
    • Great force is required.
    • Look for associated injuries.
  • Adolescents:
    • Acute fracture occurs through the growth plate (SCFE), or it is a pathologic slip (look for hypothyroidism, renal osteodystrophy).
Diagnosis
Signs and Symptoms
  • Sudden pain in the hip
  • Inability to stand or walk
  • Swelling in the inguinal crease, gluteal, proximal thigh
  • Limb held in external rotation, flexion, and adduction to relieve capsular distention
  • Resistance to any movement: Active hip motion is impossible if the fracture is displaced, and passive motion (especially flexion, abduction, and internal rotation) is restricted and painful.
  • Pain and sometimes crepitus with hip motion
  • Pseudoparalysis of the affected limb in infants
  • Extremity possibly shortened 1-2 cm
Physical Exam
  • Most children with femoral neck fractures are in extreme pain.
  • For the minority who do not have a complete fracture, pain is elicited most by internal rotation, abduction, and flexion.
Tests
Imaging
  • AP and lateral radiographic views of the hip may show upward and lateral displacement of the femoral shaft.
  • CT can be helpful for determining the direction of the femoral head dislocation.
  • In newborns, ultrasound may be helpful in showing a femoral neck fracture.
Differential Diagnosis
  • SCFE
  • Developmental coxa vara (this condition has a vertical cleft in the femoral neck)
Treatment
General Measures
  • Treatment is aimed at achieving anatomic reduction, either open or closed.
  • Use smooth PINS or cannulated 4.0-4.5-mm screws in children ~2-6 years old and cannulated 6.5-7.0-mm screws in children >7 years old.
  • Usually, a spica cast is used postoperatively because the smaller diameter of the femoral neck in these younger patients limits the size and number of screws that can be placed.
  • If the injury is type I and one must cross the physis, use smooth PINS followed by a spica cast.
  • For types II-IV, screws should not cross the physis unless the fracture cannot be stabilized without doing so; the physis of the proximal femur grows only 3 mm per year, so fear of limb-length discrepancy should not compromise fixation.
  • If the hip is dislocated, make one attempt at closed reduction, then try open reduction.
  • If open reduction is attempted, the surgical approach should be in the direction of the dislocation: Posterior for posterior dislocation, anterior for anterior dislocation.
Surgery
  • Type I:
    • Without dislocation:
      • Gentle closed or open reduction and fixation with a screw or a pin
    • With dislocation:
      • Nearly 100% develop osteonecrosis, and 80% are at risk for developing degenerative joint disease.
      • Attempt gentle closed reduction using longitudinal traction, abduction, and internal rotation; if that is unsuccessful, try immediate open reduction and pin fixation.
  • Type II:
    • Most common type
    • Most fractures are displaced.
    • Osteonecrosis in ~50% (displaced fractures at higher risk than nondisplaced)
    • Closed or open reduction and pin or screw fixation for both displaced and nondisplaced fractures
  • Type III:
    • 2nd most common type
    • Osteonecrosis in 25%
    • Displaced:
      • Gentle closed reduction or open reduction and internal fixation
    • Nondisplaced:
      • Abduction spica cast possibly adequate in children <8 years old, although late displacement or coxa vara is possible; close observation is necessary.
  • Type IV:
    • Open reduction and internal fixation with pediatric hip compression screw fixation.
  • Surgical pearls:
    • Use a fluoroscopy table or a fracture table and an image intensifier.
    • A straight lateral approach is used.
      • If intracapsular open reduction is needed, types II and III can be via a proximal extension of the tensor fascia lata-gluteus interval.
      • Type I and high type II: Use the anterior iliofemoral approach
    • The reduction maneuver includes traction and internal rotation.
    • Unacceptable reduction is indicated by a varus position or excessive displacement on AP and lateral views.
    • No displacement of the width of the femoral neck should be accepted because additional varus angulation is likely.
    • Instrumentation:
      • Types I, II, and III: Use 2-3 cannulated screws of appropriate size for age.
      • Type IV: Use a hip compression screw device with a side plate.
    • Nonoperative option: Reduce with 3-6 weeks of skeletal traction and then immobilization in hip abduction cast for a total treatment course of 12 weeks.
    • Patient age:
      • For patients 7-12 years old, use pediatric hip screw fixation, followed by hip spica cast for 8-12 weeks after surgery, depending on the stability of fixation.
      • For patients >13 years old, treat as an adult: The hip screw and side plate may cross the physis, and no postoperative immobilization is required.
    • Timing of surgery:
      • Within 24 hours
      • Type I fracture with dislocation requires immediate treatment
      • No conclusive data on the effect of timing on osteonecrosis
    • Implant removal:
      • No absolute time limit exists for removal of hardware.
      • However, it usually is removed within 12-18 months of injury, if the fracture has healed, to prevent bony overgrowth or refracture at the base of the implant.
Pediatric Considerations
  • Neonatal epiphysiolysis:
    • If recognized initially, use skin traction to restore alignment.
    • If recognized after callus formation is visible radiographically, use simple immobilization.
    • Open surgical reduction is not advised because these injuries in newborns tend to remodel if the physis does not close prematurely.
    • Close observation is necessary; a low incidence of osteonecrosis is noted.
Follow-up
Prognosis
The outcome is determined by the degree of damage to the blood supply.
 
Complications
  • Complications occur in as many as 60% of patients.
  • Most complications of pediatric hip fractures are influenced by the changing blood supply of the proximal femoral epiphysis.
  • AVN (osteonecrosis):
    • Most common, most devastating complication
    • May affect epiphysis, both epiphysis and metaphysis, or metaphysis alone
    • Develops in 42% of hip fractures in children within 9-12 months after injury:
      • Type I, nearly 100%
      • Type II, 52%
      • Type III, 27%
      • Type IV, 14%
    • Initial displacement of the fracture, fracture types I and II, and age (>10 years) are associated with increased risk.
    • Treatment:
      • Motion and containment are maintained.
      • Osteotomies to rotate the less-deformed or less-involved portion into the weightbearing region may improve congruity and symptoms.
    • Ratliff classification of osteonecrosis in children, with current commentary:
      • Type I: Total involvement and collapse of the femoral head; worst prognosis; most common injury; injury to all lateral epiphyseal vessels
      • Type II: Involvement of a portion of the epiphysis accompanied by minimal collapse of the femoral head; localized injury to the anterolateral femoral head
      • Type III: Increased sclerosis of the femoral neck from the fracture line to the physis, but sparing of the femoral head; injury to the metaphyseal vessels
  • Nonunion:
    • Occurs in 5-8% of fractures (similar to the risk in adults).
    • Closed treatment of types II and III is associated with an increased incidence of coxa vara and nonunion.
    • Internal fixation after acceptable reduction decreases the incidence of nonunion because it does not allow varus angulation or late displacement.
  • Coxa vara:
    • Secondary to growth-arrest of the proximal femoral physis or to malunion
    • If the neck shaft angle is <110°, it will not correct with remodeling.
    • Subtrochanteric valgus osteotomy, bone grafting, and internal fixation can give excellent long-term results if no osteonecrosis is present.
  • Premature closure of the physis:
    • A slight leg-length inequality results.
    • It occurs even without internal fixation crossing the physis.
    • Closure often is related to osteonecrosis.
    • The proximal femoral physis contributes growth of only 3 mm per year (~15% of total length of extremity) but, if osteonecrosis and premature closure occur, a substantial limb-length discrepancy can develop.
    • Follow with yearly scanograms and hand and wrist radiographs for bone age, with plotting on Moseley charts; consider epiphysiodesis of contralateral limb if substantial limb-length inequality develops.
    • In rare cases, symptomatic trochanteric overgrowth in children >8 years old can require trochanteric transfer.
Miscellaneous
Codes
ICD9-CM
820.08 Pediatric hip fracture
 
FAQ
Q: What is the most serious complication of femoral neck fracture in children?
A: AVN, which is an increased risk with greater displacement and with more proximal fracture.

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