Femoral Neck Fracture

Comprehensive Clinical Guide: Femoral Neck Fracture

1. Introduction & Overview

A femoral neck fracture is a subcapital, transcervical, or basicervical break in the proximal femur, located medial to the intertrochanteric line but distal to the femoral head. As a quintessential orthopedic emergency, these fractures represent a significant public health challenge, particularly in the geriatric population. Due to the unique vascular anatomy of the femoral head—which relies heavily on the medial circumflex femoral artery—fractures in this region carry a high risk of avascular necrosis (AVN) and non-union.

Clinically, these fractures are categorized as intracapsular. Because the fracture line lies within the hip joint capsule, the synovial fluid may inhibit the formation of a stable hematoma, further complicating the healing process. Management is dictated by the patient’s physiological age, bone quality, fracture displacement, and baseline functional status.

2. Pathophysiology and Mechanism of Injury

Anatomy and Vascular Compromise

The femoral neck is encased in the hip joint capsule. The blood supply to the femoral head is precarious:
* Medial Circumflex Femoral Artery (MCFA): The primary source of blood supply.
* Lateral Epiphyseal Arteries: Derived from the MCFA; these are vulnerable to disruption during displacement.
* Ligamentum Teres Artery: Provides minimal collateral circulation, usually insufficient to prevent ischemia in adults.

Mechanism of Injury

Pathological Progression

1. Disruption: The fracture causes immediate mechanical instability.
2. Vascular Insult: Displacement causes tension or rupture of the retinacular vessels, leading to ischemia.
3. Synovial Interference: Intracapsular hematoma formation leads to elevated intra-articular pressure, potentially causing tamponade of the remaining blood supply.

3. Clinical Staging and Classification

Accurate classification is essential for surgical planning. The two most utilized systems are the Garden Classification and the Pauwels Classification.

Garden Classification (Focus: Displacement)

• Stage I: Incomplete (valgus impacted) fracture.
• Stage II: Complete fracture, non-displaced.
• Stage III: Complete fracture, partially displaced (varus deformity).
• Stage IV: Complete fracture, fully displaced.

Pauwels Classification (Focus: Biomechanical Angle)

This measures the angle of the fracture line relative to the horizontal plane. Higher angles indicate increased shear forces and higher non-union risk.
* Type I: < 30 degrees (Stable).
* Type II: 30–50 degrees.
* Type III: > 50 degrees (Highly unstable; vertical shear).

4. Standard Clinical Presentation

Patients typically present with a history of a fall, followed by acute hip pain and inability to bear weight.

Physical Examination Findings

• External Rotation & Shortening: The limb is characteristically positioned in external rotation and appears shortened due to muscle pull (iliopsoas, adductors).
• Pain on Motion: Passive range of motion, particularly internal rotation, elicits severe pain.
• Tenderness: Palpation over the greater trochanter or the groin area.
• Neurovascular Status: Essential to rule out associated sciatic nerve injury, though rare in isolated femoral neck fractures.

5. Diagnostic Protocol

Imaging Requirements

1. AP Pelvis: To compare the injured side with the contralateral hip.
2. Cross-table Lateral Hip: Essential to assess posterior comminution and displacement.
3. MRI (Gold Standard for Occult Fractures): If plain radiographs are negative but clinical suspicion remains high (e.g., geriatric patient with persistent pain after a fall).
4. CT Scan: Used for preoperative planning to assess the degree of comminution and fracture geometry.

6. Management: Surgical Considerations

The treatment paradigm is generally divided by age and displacement.

7. Risks, Side Effects, and Complications

• Avascular Necrosis (AVN): Occurs in 10-30% of displaced fractures due to the compromise of the medial circumflex femoral artery.
• Non-Union: High risk due to the lack of periosteum in the femoral neck, which limits callus formation.
• Hardware Failure: Migration of screws or cutout through the femoral head.
• Infection: Risk associated with any orthopedic internal fixation.
• Thromboembolism: Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE) are significant post-operative risks.

8. FAQ: Frequently Asked Questions

Q1: Why is a femoral neck fracture considered an emergency?
A1: Because of the high risk of vascular compromise to the femoral head. Early stabilization (within 24–48 hours) is associated with better outcomes and lower mortality.

Q2: What is the difference between a femoral neck fracture and an intertrochanteric fracture?
A2: Femoral neck fractures are intracapsular (inside the hip joint), while intertrochanteric fractures occur extracapsularly. Intertrochanteric fractures have a better blood supply and higher union rates.

Q3: Can I walk on a femoral neck fracture?
A3: Absolutely not. Weight-bearing on an undiagnosed or unstable fracture can cause further displacement, damage the blood supply, and lead to permanent bone death.

Q4: How long is the recovery period?
A4: Recovery varies. Simple fixation may require 6–12 weeks of restricted weight-bearing, while arthroplasty patients may mobilize within 24 hours but require 3–6 months for full rehabilitation.

Q5: What is the role of the Garden classification?
A5: It helps surgeons decide whether to fix the bone (internal fixation) or replace it (arthroplasty) based on how much the bone has shifted.

Q6: Why are elderly patients at higher risk?
A6: Osteoporosis reduces bone mineral density, making the femoral neck brittle. Additionally, balance deficits and sarcopenia increase fall frequency.

Q7: Is MRI always necessary?
A7: No. MRI is reserved for "occult" fractures where the patient has clinical symptoms but the X-rays appear normal.

Q8: What is a "valgus impacted" fracture?
A8: A Garden Stage I fracture where the bone fragments are driven into each other, providing inherent stability. These are often treated conservatively with close monitoring.

Q9: What are the symptoms of AVN?
A9: Chronic groin pain, stiffness, and a "grinding" sensation in the hip joint, occurring months or years after the injury.

Q10: Are there non-surgical options?
A10: Non-surgical management is almost exclusively reserved for patients who are medically unfit for anesthesia. It carries a high risk of long-term immobility and mortality.

9. Long-term Prognosis and Rehabilitation

The prognosis depends heavily on the initial displacement and the quality of the surgical reduction.

Key Factors for Positive Outcomes:

• Time to Surgery: "The Golden Window" is less than 24 hours to reduce the risk of secondary vascular damage.
• Rehabilitation: Immediate physical therapy focusing on early mobilization is critical to preventing pneumonia, pressure ulcers, and muscle atrophy.
• Bone Health Management: Post-fracture, all geriatric patients should be screened for osteoporosis (DEXA scan) and started on bisphosphonates or other anti-resorptive therapies to prevent secondary fractures.

Summary Table: Long-Term Outlook

Concluding Expert Note

Femoral neck fractures are not merely structural failures of bone; they are systemic events that alter the life trajectory of the patient. The modern orthopedic approach emphasizes "fast-track" surgery, multidisciplinary geriatric co-management, and aggressive rehabilitation. By addressing both the mechanical instability and the underlying metabolic bone disease, clinicians can optimize the chance of returning the patient to their previous level of function.

Disclaimer: This guide is for educational purposes for medical professionals and students. Clinical decisions must always be guided by institutional protocols, evidence-based guidelines (such as AAOS), and the individual patient’s clinical presentation.

Related Clinical Integration

In a modern clinical setting, the management of a Femoral Neck Fracture requires a multidisciplinary approach that integrates pharmacological pain control, surgical intervention, and specialized rehabilitation. Patients typically require Analgesics (e.g., Acetaminophen, Opioids) / مسكنات الألم (مثل: أسيتامينوفين، الأفيونات) Standard, such as Acetaminophen-Codeine / أسيتامينوفين-كوديين 300mg / 30mg or Conzip / كونزيب 100mg, to manage acute pain, while Anticoagulants (e.g., Citrate, Heparin) / مضادات التخثر (مثل السترات، الهيبارين) Standard are essential for preventing venous thromboembolism. Surgical stabilization often involves procedures such as Cemented Hemiarthroplasty for Pathologic Fracture / رأب نصف المفصل الملحوم لكسر مرضي (عملية كبرى في غرف العمليات), which are detailed in clinical resources like Femoral Neck Fracture Fixation: A Masterclass in Percutaneous Cannulated Screw Osteosynthesis and Hemiarthroplasty for Displaced Femoral Neck Fractures: An Intraoperative Masterclass. Post-operative recovery is supported by mobility aids like