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Images
https://upload.orthobullets.com/topic/12293/images/femo_neck_nonunion.jpg
https://upload.orthobullets.com/topic/12293/images/coronal_ct..jpg
https://upload.orthobullets.com/topic/12293/images/leighton_1..jpg
https://upload.orthobullets.com/topic/12293/images/leighton_2c.jpg
https://upload.orthobullets.com/topic/12293/images/xr_femoral_neck_nonunion.jpg
https://upload.orthobullets.com/topic/12293/images/valgus_it_osteotomy_xr.jpg
  • Summary
    • Femoral neck fracture nonunion represents a failure of bony healing after fixation of an intracapsular femoral neck fracture.
    • Diagnosis is generally confirmed by radiographs demonstrating residual fracture lines, interval displacement and hardware failure.
    • Treatment is operative ranging from valgus intertrochanteric femoral osteotomy to total hip arthroplasty depending on available bone stock, presence of avascular necrosis and patient age. 
  • Epidemiology
    • Incidence
      • occur after 10-30% of femoral neck ORIF
    • Demographics
      • increasing age at higher risk for nonunion
    • Risk factors
      • fracture morphology
        • significant initial displacement
        • vertically oriented fracture pattern (Pauwels type III)
        • posterior comminution
      • fracture malreduction, particularly with varus malalignment
      • older age
      • delay of fracture fixation >24 hours
  • Etiology
    • Pathophysiology
      • mechanism of injury
        • initial femoral neck fracture occurs due to high energy trauma in the younger population, and ground-level falls in the elderly
        • nonunion occurs after fracture displacement and/or hardware failure before bony consolidation
      • pathoanatomy
        • femoral neck fractures are intracapsular, placing them at higher risk for nonunion than other hip fractures
          • lack periosteal or extraosseous blood supply
          • bathed in synovial fluid which deters fracture healing
          • healing is intra-osseous only (no callus formation)
            • achieving and maintaining anatomic reduction is essential
    • Associated conditions
      • orthopaedic conditions
        • avascular necrosis (AVN)
        • femoral neck malunion
        • hardware failure
        • surgical site infection leading to septic nonunion
      • medical conditions or comorbidities
        • low bone mineral density
  • Anatomy
    • Osteology
      • normal proximal femur neck shaft-angle 130 +/- 7°
      • normal proximal femur anteversion 10 +/- 7°
      • proximal femur consists of tensile and compressive trabecular groups
    • Muscles
      • hip abductors
        • important to preserve neurovascular supply and attachments of abductors to avoid abductor lurch and Trendelenburg gait
    • Ligaments
      • iliofemoral, ischiofemoral and pubofemoral ligaments attach to outer hip capsule and help to prevent excessive hip motion
    • Blood Supply
      • a confluence of arteries forms an extracapsular arterial ring that divides into the ascending cervical arteries which supply the femoral neck via perforators
        • main blood supply in adults is the medial femoral circumflex artery (lateral epiphyseal artery)
        • lateral femoral circumflex contributes to anterior arterial ring
        • superior and inferior gluteal arteries give small contributions to arterial ring
        • artery of ligamentum teres comes from obturator or medial femoral circumflex
          • plays insignificant role in blood supply
      • femoral neck fracture with displacement is thought to disrupt the blood supply to the femoral neck
    • Biomechanics
      • in double-leg stance, force vector through hip is vertical
      • in single-leg stance, force vector through hip is parallel to femoral neck
        • compressive load through hip is 4x bodyweight
        • repetitive loading can increase tensile forces and lead to superior femoral neck fracture
  • Classification
    • Primarily descriptive
      • Leighton's classification
      • Type 1
      • Inadequate fixation or non-anatomic reduction
      • Type 2
      • Loss of fixation with fracture displacement
      • Type 3
      • Fibrous nonunion with no displacement and intact fixation
  • Presentation
    • History
      • prior femoral neck fracture
      • evaluation of medical history
        • low bone density
        • metabolic disease
        • nutritional deficiencies
        • tobacco use
    • Symptoms
      • persistent groin/buttock pain
      • pain with weight bearing
      • pain with hip extension
      • pain may radiate down medial thigh/knee
    • Physical exam
      • inspection
        • important to evaluate prior incision for drainage, erythema and to verify approach of prior surgery
      • motion
        • discomfort with active or passive range of motion at hip
          • decreased internal rotation
        • antalgic gait
      • neurovascular
        • evaluate sciatic and femoral nerve function
      • provocative tests
        • pain with log-roll
        • pain with straight leg raise
  • Imaging
    • Radiographs
      • recommended views
        • AP pelvis and hip
        • cross-table lateral hip
        • full length femur
        • optional views
          • traction/internal rotation hip view
          • contralateral hip films for intraoperative templating
      • findings
        • radiolucent fracture lines
        • fracture settling
        • failure of hardware (backing out)
        • perforation of femoral head with hardware
        • change in fracture position by >10mm
        • femoral head collapse (AVN)
        • calcar comminution
        • varus malalignment
    • CT
      • indications
        • most definitive way to diagnose femoral neck nonunion
        • useful if diagnosis uncertain or for surgical planning
    • MRI
      • indications
        • concern for diagnosis of femoral head AVN in the setting of nonunion
    • Bone scan
      • indications
        • may help rule out concomitant femoral head AVN
      • findings
        • may show increased uptake in area of the nonunion
  • Studies
    • Labs
      • indications
        • must rule out infection
      • inflammatory markers
        • CBC with manual diff
        • ESR
        • CRP
    • Hip aspiration
      • indications
        • if high suspicion for infection in the setting of elevated inflammatory markers
    • Intraoperative tissue sample
      • if concerned for infection, can send frozen-section for histology before proceeding with further fixation
        • if positive for infection, staged approach preferred
  • Treatment
    • Nonoperative
      • observation
        • indications 
          • only indicated in non-ambulatory patients with comorbid conditions
        • outcomes
          • poor functional outcomes with non-operative management
    • Operative
      • revision ORIF
        • indications
          • not recommended due to:
            • proximal bone loss
            • residual leg length discrepancy
            • high residual failure rates
      • proximal femoral osteotomy
        • indications
          • failure of fracture fixation
          • nonunion >3 months postoperatively
          • varus collapse
        • considerations
          • femoral head viability
          • remaining femoral neck bone quality
          • patient age
            • in younger patients, arthroplasty may be less desirable 
          • duration of nonunion
            • longer duration may cause contractures, fibrosis and acetabular wear
        • techniques
          • valgus intertrochanteric osteotomy   
            • most commonly used salvage procedure
              • primary issue is mechanical orientation of fracture in this group
              • technique reorients vertical fracture to a horizontal fracture to achieve compression at the nonunion site
              • improves abductor function by restoring femoral length and abductor lever arm
              • patients may still describe persistent limp due to abductor weakness
          • contraindications
            • significant bone loss
            • joint incongruity
            • age > 65 (relative)
          • outcomes
            • 80-90% union rates
            • high percentage of associated femoral head AVN but only small percentage remain symptomatic after osteotomy
      • bone grafting
        • indications
          • failed prior fixation attempts
          • nonunion remains well aligned with loss of posterior bone stock
        • techniques
          • quadratus femoris-vascularized pedicle graft
          • free vascularized fibular grafting
        • outcomes
          • may not be as beneficial when fracture malalignment is primary cause of nonunion
          • union rates up to 90%
      • hip hemiarthroplasty
        • indications
          • low physical demand and more comorbidities
          • cognitive decline
        • techniques
          • cemented vs. uncemented
        • outcomes
          • less extensile than THA
          • lower dislocation rate compared with THA
        • contraindications 
          • significant acetabular erosion
      • total hip arthroplasty
        • indications
          • salvage operation of choice in older patients with femoral neck fracture nonunion  
            • prior femoral bony defect
            • poor acetabular bone quality
        • outcomes
          • excellent 10-year survivorship (~90%)
            • improved for patients greater than 65
        • complications
          • dislocation
            • rates may be decreasing with advent of new implant technologies
          • trochanteric nonunion
          • thromboembolic complication
          • loosening
          • infection
      • hip arthrodesis
        • indications
          • young patients with nonviable femoral heads
          • heavy manual laborers
        • outcomes
          • arthroplasty becoming favored over arthrodesis, even at young age
  • Technique
    • Observation
      • bedrest, non-weightbearing on affected extremity
      • complications
        • may increase risk for other systemic complications
    • Revision ORIF
      • approach
        • through initial incision when appropriate
      • technique
        • removal of hardware, adequate reduction of fracture
        • new stable bony fixation with bone grafting
      • complications
        • very high failure rates
        • residual leg length discrepancy
    • Valgus intertrochanteric osteotomy
      • approach
        • direct lateral approach to proximal femur
      • technique
        • goal is to convert vertically oriented fracture to about 30 degrees in order to create compression
        • can use blade plate or sliding hip screw for ultimate fixation
      • complications
        • femoral malrotation
        • excessive medialization of femoral shaft can decrease offset
          • cause abductor efficiency
          • a longer blade can avoid medialization of shaft
    • Bone grafting
      • approach
        • lateral incision just anterior to greater trochanter between 10-15cm long
      • technique
        • quadratus femoris-vascularized pedicle graft
          • insertion of quadratus taken down off the greater trochanter with a bony flap that is transplanted to the posterior femoral neck and sutured or fixed into place with screws
        • free vascularized fibular grafting
      • complications
        • donor site morbidity
        • may need to be combined with mechanical realignment
    • Hip hemiarthroplasty
      • approach
        • posterior
        • anterolateral
        • direct anterior
      • technique
        • unipolar vs. bipolar
          • recent studies have not shown bipolar femoral heads to provide any benefit over unipolar heads
        • cemented shows superior outcomes, fewer complications than uncemented
      • complications
        • results of failed hip hemiarthroplasty when converted to THA are worse than primary THA.
    • Total hip arthroplasty
      • approach
        • similar to hip hemiarthroplasty
      • technique
        • there may be residual bony defects in proximal femur from old hardware
          • may have to bypass this area with longer stems
          • may increase risk for intraoperative fracture while reaming the canal
        • poor acetabular bone quality can make cup placement difficult and increase risk for fracture
          • avoid overly aggressive acetabular component impaction
          • augment cup with screws
      • complications
        • dislocation
          • use of larger diameter heads and new implant technology (i.e dual mobility) may be helpful in decreasing dislocation rates
        • increased rates of aseptic loosening
          • risks include patient age < 65 and BMI >30.
    • Hip arthrodesis
      • approach
        • lateral approach with trochanteric osteotomy
      • technique
        • optimal positioning of hip joint:
          • 20-35° hip flexion
          • 0-5° adduction
          • 5-10° external rotation
      • complications
        • adjacent joint arthrosis/pain
        • low back pain
  • Complications
    • Concomitant femoral head AVN
      • incidence
        • up to 40% in setting of nonunion
        • around 15% appear to be symptomatic
      • risk factors
        • initial fracture displacement
        • poor reduction
      • treatment
        • hip arthroplasty
    • Acetabular cartilage degeneration
      • risk factors
        • associated femoral head AVN or chondral wear
      • treatment
        • total hip arthroplasty
    • Trendelenburg gait
      • risk factors
        • loss of femoral offset secondary to abductor inefficiency in nonunion/malunion or valgus producing osteotomy
      • treatment
        • avoiding loss of femoral offset or damage to abductors during salvage operations
    • Prosthetic dislocation
      • incidence
        • 10-20% in salvage total hip arthroplasty group compared to <10% in primary arthroplasty group after femoral neck fracture
      • risk factors
        • abductor insufficiency
        • abnormal hip joint kinematics after nonunion
        • posterior hip approach
      • treatment
        • larger femoral heads, dual mobility implants may decrease risk
        • choose surgical approach to optimize stability
  • Prognosis
    • Natural history
      • typically, patients present with pain and difficulty with ambulation months after fixation
        • persistent pain with radiographic lack of healing at 3 months signifies likely nonunion.
          • revision surgery should be considered at this point.
    • Prognostic variables (poor)
      • unfavorable fracture patterns
      • malreduction
      • poor bone quality
    • Survival with treatment
      • valgus intertrochanteric osteotomy
        • eventual union rates of 80-90%
      • hip arthroplasty
        • approximately 90% implant survivorship at 10 years, 75% at 20 years.
        • higher rate of dislocation (up to 10-20%), compared to primary hip arthroplasty
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