Femoral Neck Fracture

Femoral neck fractures are intra-capsular fractures of the proximal femur, at the neck of the femur between the trochanteric line and head of the femur. They are associated with avascular necrosis of the head of the femur, impaired healing and have a high risk of morbidity and mortality. Stress fractures uncommon, but are possible, especially in athletes who are starting a new activity.

Treatment depends on displacement of the fracture, bone quality and location of the fracture.

Bimodal distribution. Affects women more than men. it has a high mortality, with a 25 – 30% 1 -year risk.

Garden classification: based on AP X-ray to determine management based on stability of the fracture. Does not consider lateral or sagittal plane alignment. Posterior roll-off and/or angulation of the femoral head leads to increased reoperation rates

Classification	Description	Treatment
Type I	Incomplete fracture, valgus impacted	Cannulated screw fixation
Type II	Complete fracture , non-displaced	Cannulated screw fixation
Type III	Complete fracture, partially displaced (< 50%)	ORIF, Hemiarthroplasty vs total hip arthroplasty
Type IV	Complete fracture, fully displaced	ORIF, Hemiarthroplasty vs total hip arthroplasty

Simplified Gardens Classifiaction

Classification	Gardens	Treatment
Non-displaced	Garden type I and type II	Cannulated screw fixation
Displaced	Garden type III and IV	Hemiarthroplasty vs total hip arthroplasty

Pauwels classification for femoral neck fracture (looks at orientation of the fracture line to determine stability)

Classification	Description
Type I (stable)	< 30 degrees from horizontal
Type II (less stable)	30 – 50 degrees from horizontal
Type III (unstable)	> 50 degrees from horizontal. Most unstable with the highest risk of avascular necrosis

• Anatomy
  • The femoral neck is intracapsular with limited blood supply. It lacks a periosteal layer and is surrounded by synovial fluid. It’s limited blod supply impairs hearing
  • Parts include subcapital vs transvervical vs basicervical
  • Neck to shaft angle is about 130 degrees and an angle of anteversion of about 10 degrees
  • Major blood supply is the lateral epiphyseal branch of the medial femoral circumflex artery. Other branches arise from the lateral femoral circumflex, inferior gluteal artery and insignificant supply from the arter yo fht eligamentum teres. A displaced fracture disrupts blood supply to the femoral he
  • The calcar femorale is located in the posteromedial aspect and made of a dense plate of bone. It transfers stress from the trabecular bone of the head to the cortical boen of the shaft.
• Mechanism
  • High energy mechanism (young patients)
    • Motorvehicle accident
    • Fall from height
  • Low energy mechanism (elderly or osteoporotic)
    • Fall from standing height
• Associated injuries
  • Femoral shaft fracture (6-9%, femoral neck fractures are treated before the femoral shaft fracture)
• Signs and symptoms
  • Groin pain (impacted and stress fracture)
    • Referred to the medial thigh and knee
  • Severe pain along the entire hip region (displaced fracture)
  • Inability to bear weight
• Physical examination
  • Pain with log roll or straight leg raise
  • No obvious deformity (non-displaced)
  • External rotation and shortening (displaced – natural position of the femur when it is not held by ligaments)
  • Tenderness on percussion of th egreater trochanter
• Investigations
  • X**-ray:** AP pelvis, AP Hip, cross-table lateral hip, full-length femur and traction-internal rotation AP hip
    • AP view to determine lateral displacement
    • Cross-table lateral view to ****determine AP displacement
  • CT scan: to determine displacement and degree of comminution. Also for surgical planning
  • MRI: Gold standard for occult fracture
  • Bone scan: to rule out occult fracture
  • Dopple ultrasound of both lower limbs: to rule out DVT in patients with delayed presentation after hip fracture
• Conservative treatment
  • Observation: in non-ambulatory patients with minimal pain and high surgical risk
• Operative treatment
  • Closed reduction with Percutaneous fixation (inverted triangle of partially threaded cannulated screws): for non-displaced fractures in physiologically elderly and displaced transcervical fractures in young patients. Open reduction may be performed for anatomic reduction.
  • Open reduciton internal fixation (ORIF) with sliding (dynamic) hip screw: for displaced fractures in young or physiologically young patients with basicervical and vertical fractures.
  • Arthroplasty
    • Hemi-arthroplasty: for displaced fractures in debilitated and less active patients. No advantage between unipolar and bipolar heads
    • Total hip arthroplasty: for displaced fractures in more-active patients with pre-existing acetabular disease or arthritis.
• Prognostic factors
  • Pre-injury ambulatory status (most important predictor for post-op survival)
  • Age
  • Cognitive function
  • Comorbidities
  • Time of surgery (mortality decreases if surgery is performed within 48 hours)
• Complications of femoral neck fracture
  • Avascular necrosis: risk is increased with a displaced fracture and in non-anatomic reduction
  • Deep venous thrombosis
  • Post-operative non-union: especially in ORIF
  • Malunion: varus malreduction. Treated with intertrochanteric osteotomy or arhtoplasty
  • Dislocation of prosthesis (10%): Risk is higher with total hip arthroplasty than hemiarthroplasty