26. Fracture of the femoral neck

Essay 26- Fracture of the neck of the femur

Definition

• Femoral neck fractures are a specific type of intracapsular hip fracture!
• The femoral neck connects the femoral shaft with the femoral head

Etiology

• Indirect flexion caused by a sideways fall on the trochanter with an abrupt external rotation of the extremity
• Low-energy trauma in elderly
• Indirect scissor-like mechanism is also responsible in younger people

Pathophysiology

• The chief source of vascular supply to the femoral head is the medial femoral circumflex artery
• Displaced fractures of the femoral neck put the blood supply at risk, usually tearing the ascending cervical branches that stem off the arterial ring supply formed by the circumflex arteries
• This may compromise the healing ability of the fracture, inevitably causing non-union or osteonecrosis

Classification

According to anatomical location

• Sub-capital
• Mediocervical
• Basocervical
• Trochanteric

Garden classification

• Type I- Incomplete fracture - valgus impacted-non displaced
• Type II- Complete fracture - nondisplaced
• Type III- Complete fracture - partial displaced
• Type IV- Complete fracture - fully displaced

Pauwel classification

• Type I- less than 30 degrees
• Type II- 30 to 50 degrees
• Type III- greater than 50 degrees
• Higher angles and more vertical fractures exhibit greater instability!

Symptoms

• In abduction fractures, the patients are able to lift the limb and the symptom of ‘the nailed heel’ is absent
• Adduction fractures are dislocated and unstable
• Pain in hip bone and inability to move limb

Diagnosis

• Neurovascular examination of extremity
• X-ray
• 2 projections needed
• Face projection reveals varus, valgus fracture and degree of dislocation
• CT
• MRI
• Basic labs
• ECG

Treatment

• Treatment is usually operative
• Young patients will require treatment with emergent open reduction, internal fixation, arthroplasty (uni or biploar)
• Vertically oriented fractures such a Pauwel type III fracture are more common
• Non-displaced fractures are treated typically with percutaneous cannulated screws or a sliding hip screw
• However, there a higher rate of avascular necrosis with a sliding hip screw!