Fracture of the Neck of Femur (NOF Fracture / Hip Fracture)

Epidemiology

• Mortality in the first year after a femoral neck fracture is ~14%, compared with ~9% in a matched control population
• Risk factors for higher mortality: age, male sex, psychiatric illness, end-stage renal disease, congestive heart failure, and institutionalisation (death rate up to 3x higher)

Anatomy & Blood Supply

1. Retinacular vessels (most important) - branches of the medial circumflex femoral artery running deep to the synovium along the femoral neck in fibrous retinacula
2. Medullary cavity vessels - attenuated with age due to fatty marrow replacement
3. Ligamentum teres artery - also attenuated with age and atherosclerosis

Classification

By Location (Anatomical)

Garden Classification (Intracapsular Fractures)

Delbet Classification (Paediatric)

Clinical Presentation

• Severe groin/hip pain, unable to weight-bear
• Limb held in shortening, external rotation, and abduction
• Range-of-motion assessment should be deferred to avoid further vascular disruption

• May be ambulatory
• Groin or inner thigh pain, aggravated by walking and weight-bearing
• Night pain can develop if diagnosis is delayed (athletes)
• On examination: discomfort at extremes of rotation (especially internal rotation)

Investigations

• Displaced fractures are obvious on AP view
• A lateral view is critical - it often reveals fractures not visible on AP
• Look for: disruption of the bony cortex or trabecular lines
• Impacted undisplaced fractures show a sclerotic line and/or disrupted trabecular pattern
• ~15% of fractures are difficult to detect on plain films
• ~6-9% have an ipsilateral femoral shaft fracture (always check in high-energy trauma)
• Note: Shenton's line and neck-shaft angle are unreliable for fracture identification

Management

Emergency Department

• Maintain the extremity in a position of comfort
• No additional external immobilisation required
• Skeletal traction is contraindicated - may worsen AVN by stretching retinacular vessels
• "Buck's" boot traction is no longer recommended

Surgical Management

Undisplaced Intracapsular Fractures (Garden I/II)

• Cannulated screws - 3 partially threaded screws (6.5-7.3 mm) in an inverted triangle configuration, inserted under fluoroscopy
• Allows preservation of the native femoral head
• Internal fixation reduces hospitalisation length and improves rehabilitation

Displaced Intracapsular Fractures (Garden III/IV)

• Elderly patients / low functional demand:
  • Hemiarthroplasty (Austin Moore, Thompson, bipolar) - femoral head replaced, acetabulum left native. Allows immediate weight-bearing.
  • Recent evidence (2025 meta-analysis, PMID 40270012) suggests dual mobility cups may reduce dislocation risk vs conventional hemiarthroplasty
• Younger, independently mobile patients:
  • Total hip arthroplasty (THA) - better functional outcomes, more appropriate when acetabular cartilage may be worn
  • A 2024 systematic review (PMID 39436746) compared supercapsular percutaneous approaches vs standard posterior approach for THA in this setting
• Young patients (<60 years) with undisplaced intracapsular fractures:
  • ORIF with dynamic hip screw (DHS) or multiple cannulated screws, aiming to preserve the native head

Extracapsular Fractures (Intertrochanteric / Subtrochanteric)

• Stable extracapsular fractures:
  • Dynamic hip screw (DHS) - a sliding screw in a barrel that allows controlled compression at the fracture site on weight-bearing, protecting the femoral head from screw penetration in osteoporotic bone

• Unstable extracapsular fractures (reverse oblique pattern, comminuted medial calcar/lesser trochanter):
  • Intramedullary device (cephalomedullary nail) preferred due to unfavourable mechanics with DHS

Paediatric Fractures (Delbet Types I-III)

• Surgical emergencies - ORIF urgently
• Smooth pins in younger children; threaded pins in adolescents
• Post-op spica casting may be required in younger/more severe injuries

Complications

Recent Evidence Note: A 2025 meta-analysis (PMID 41303766) found that thromboembolic risk after THA vs hemiarthroplasty may differ - review VTE prophylaxis protocols accordingly.

Key Teaching Points

1. Femoral neck fractures are mostly intracapsular - subcapital, transcervical, basicervical
2. Blood supply is tenuous at baseline in the elderly (attenuated medullary and ligamentum teres vessels); a displaced fracture tears the retinacular vessels, making AVN nearly inevitable
3. Extracapsular fractures (intertrochanteric) do not disrupt femoral head blood supply - DHS is the treatment of choice
4. The classification that matters most clinically: displaced vs undisplaced (not Garden I/II/III/IV in isolation)
5. MRI is the gold standard for occult fractures when plain films are negative
6. Skeletal traction is contraindicated - it stretches and may occlude the retinacular vessels