Updated: 3/7/2022

Femoral Neck Fx Nonunion

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  • 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 discrepancyhigh residual failure rates
            • 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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(OBQ15.30) A 76-year-old male community ambulatory presented to clinic complaining of pain in the left groin that has been persistent for the last 8 months. Radiographs obtained from clinic are seen in Figure A. You suspect a femoral neck nonunion and obtain a CT scan which confirmed it. Which of the following statements is true?

QID: 5715

Total hip arthroplasty will provide patient with the best long term outcomes



Valgus malreduction is closely correlated with failure of fixation after reduction and cannulated screw fixation



The patient's best outcome would be with an open reduction, bone grafting, and changing to an inverted triangle configuration of screws



The most appropriate treatment is a valgus osteotomy to correct malreduction



Providing this patient with a hemiarthroplasty increases rates of postoperative dislocation when comparing to total hip arthroplasty



L 1 B

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