Young Fractured Neck of Femur (under 65)

Young NOF (<65 young, >75 old, physiology depended in between)

You are called to A&E to see a 42 year old cyclist who has fallen off his bike on an icy road.   He is complaining of hip pain and his leg  is said to be shortened, flexed and externally rotated.  How would you proceed?

DHSAssesment

  • ATLS / Trauma screen
  • Associated injuries common – life threatening first then hip should be delt with immediately following this
  • Shortened, flexed, externally rotated lower limb
  • Radiographic evaluation – AP pelvis, Lateral of hip
  • Ipsilateral femoral neck fractures noted in 2-6% of femoral shaft fractures

Mechanism of injury:

  • High energy, axial load with hip abducted
  • Fracture therefore tends to be basicervical or more distal neck
  • More vertical than in the elderly – biomechanically less stable

Classifcation:

  • Pauwels classification
  • 1 more stable than 3
  • 3 inc risk of fixation failure, malunion, avn

Anatomy:

  • Medial femoral circumflex artery – largest supply –
  • Lateral femoral circumflex artery – inferior metaphyseal artery – inferioanterior aspect of femoral head
  • Obturator artery – little & variable blood supply in adults via ligamentum teres

Management:

  • Elderly – restore mobility with weight bearing as tolerated to minimize complications seen with bed rest
  • Fix or replace – age, physiological age, level of activity, bone quality, co-morbidities, fracture pattern & characteristics
  • Goals: Preserve head, avoid AVN, achieve union, avoid THR
  • Non displaced – internal fixation – non-op = higher risk displacement & high complication rate

Surgical approach

  • Medical optimization
  • Leave limb shortened, flexed & externally rotated until in theatre – lowest intracapsular pressure
  • Closed reduction in theatre
    • Flex hip to 45 degrees, slightly abducted & then extend & internally rotate, whilst applying longitudinal traction
    • Quality of reduction assessed on II fluroscopy
    • Anatomic reduction – percutaneous internal fixation
    • Non-Anatomic reduction – open reduction internal fixation
      • Supine with or without traction
      • Watson-Jones approach (smith-peterson can but used but then requires another incision for fixation)
      • Open anatomic reduction – checked with II
      • 3 cannulated or non cannulated cancellous screws

Post Op

  • 24 hrs IV abx
  • VTE Prophylaxsis (until FWB)
  • Physio
  • Toe-touch weight bearing for 12 weeks
  • FWB when then have strength, balance , wean off crutches when can walk without a limp)
  • Regular radiographic surveillance (monthly)
  • MRI is not a good predictor of post traumatic AVN
  • Peristent pain in groin & trochanter = AVN
  • NO pain & normal XR @ 24 months – discharge
  • Question about union @4-6 months = CT to asses fracture line

Fixation

  • 3 x 7.3mm cancellous lag screws parallel to one another & perpendicular to fracture line
  • Inverted triangle – lower risk of subtrochanteric fracture
  • Inferior screw to rest on medial aspect of of distal femoral neck – resists varus displacement
  • Basicervical fracture with comminution – DHS – additional derotation screw doesn’t enhance mechanicals stability… but stops displacement on insertion of DHS screw
  • Pauwells 3 – potentially DHS is better for fixation, but lmore bone loss, risk of disturbing femoral head blood supply if poorly placed, inability to control rotations without de-rotation screw

Capsulotomy

  • Controversial – too few cases for a well powered study
  • Reduce the tamponade effect

AVN

  • Vascular damage from initial fracture
  • Quality of reduction / fixation of fracture (whether blood flow has been restored to distorted arteries)
  • Elevated intracapsular pressure
  • Time to theatre
  • Time to full weight bearing

Time to surgery

  • Controversial – inconclusive research
  • Jain et al <12hrs 0%, >12hrs 16% developed AVN.
  • Given lack of research – urgent surgery recommended

Outcome

  • Generally good
  • AVN risk is between 12-86% in the studies, average is 23%

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