Femoral Neck Fracture

A femoral neck fracture is an intracapsular fracture between the femoral head and intertrochanteric region.

The intracapsular location is clinically important because the femoral neck has limited periosteal healing and displacement can disrupt branches of the medial femoral circumflex artery supplying the femoral head.

Major complications are:

• Osteonecrosis of the femoral head
• Nonunion
• Femoral neck shortening
• Fixation failure

In younger patients the priority is preservation of the native femoral head.

In older patients with displaced fractures the priority is reliable immediate reconstruction and mobilisation, usually with arthroplasty.

Anatomical classification

Subcapital

Immediately below the femoral head.

Transcervical

Through the midportion of the femoral neck.

Basicervical

At the base of the neck close to the intertrochanteric region.

Basicervical fractures behave more like extracapsular mechanically unstable fractures and may require stronger sliding or fixed angle constructs.

Garden classification

Based primarily on displacement on the AP radiograph.

Garden I

• Incomplete fracture
• Usually valgus impacted

Garden II

• Complete fracture
• Nondisplaced

Garden III

• Complete fracture
• Partially displaced
• Some residual contact between head and neck

Garden IV

• Complete fracture
• Fully displaced

For treatment purposes:

• Garden I and II = nondisplaced
• Garden III and IV = displaced.

Pauwels classification

Based on inclination of the fracture line from horizontal.

Type I: less than 30°

Predominantly compressive forces.

Type II: 30° to 50°

Increasing shear.

Type III: greater than 50°

Highly vertical, shear dominant fracture with greater mechanical instability and nonunion risk.

Older patients typically present after a low energy fall with groin pain and inability to bear weight.

A displaced fracture produces:

• Shortened limb
• External rotation
• Pain with any hip movement

A valgus impacted fracture can be surprisingly subtle and some patients remain able to walk.

Young patients usually sustain these fractures through high energy trauma and require assessment for additional injuries.

AP pelvis and cross table lateral hip radiographs: initial imaging.

Avoid a forced frog leg lateral when a fracture is suspected because it can displace an unstable fracture.

If fracture remains strongly suspected despite normal radiographs:

MRI: preferred occult fracture investigation.

If MRI is unavailable within approximately 24 hours or contraindicated, CT is an appropriate alternative.

Initial management

Provide adequate analgesia.

A fascia iliaca or femoral nerve block can markedly reduce opioid requirements in older patients.

Correct reversible physiological problems promptly rather than delaying surgery unnecessarily.

For geriatric hip fracture, operate on the day of admission or the following day where possible.

Young or physiologically young patient

Preserve the femoral head whenever feasible.

A displaced femoral neck fracture requires urgent anatomical reduction and stable internal fixation.

Reduction goals are:

• Restore normal neck shaft angle
• Correct rotational displacement
• Avoid varus
• Restore posterior cortical alignment

Poor reduction cannot be compensated for by excellent hardware.

If acceptable reduction cannot be obtained closed, perform open reduction rather than accepting malalignment.

Garden I or II, low angle fracture

Multiple parallel cannulated screws can provide adequate fixation.

Basicervical or Pauwels III fracture

A sliding hip screw, femoral neck system or another fixed angle construct generally provides greater resistance to vertical shear than isolated parallel screws. A supplementary antirotation screw may be used with selected constructs.

Severe posterior comminution increases instability.

Protected weight bearing is usually required after fixation in younger patients until sufficient healing occurs.

Older patient with nondisplaced fracture

Garden I and II fractures are commonly treated with internal fixation using cannulated screws or another low morbidity fixation system.

Very elderly patients with substantial posterior tilt, poor bone quality or a high likelihood of fixation failure require individual consideration because arthroplasty may sometimes provide a more reliable outcome.

Older patient with displaced fracture

Garden III or IV fracture should usually undergo arthroplasty rather than internal fixation.

Use hemiarthroplasty for patients with lower functional demand, significant frailty or limited independent life expectancy.

Consider total hip arthroplasty when the patient:

• Previously walked independently outdoors with no more than a stick
• Is medically suitable for the larger operation
• Is expected to remain independently functional for more than approximately 2 years.

Use a cemented femoral stem for hip fracture arthroplasty in most older adults unless a specific contraindication exists.

Postoperative care

Aim for immediate or early weight bearing as tolerated after stable arthroplasty or appropriate geriatric fixation.

Mobilise beginning the day after surgery where possible.

For fragility fractures of the hip or proximal femur, provide pharmacological venous thromboembolism prophylaxis for approximately 1 month when bleeding risk permits. LMWH can begin approximately 6 to 12 hours after surgery.

Investigate and treat osteoporosis because the fracture is frequently a sentinel fragility event.