Residency · Residency · Orthopedic Surgery

Femoral Neck Fractures: Fixation vs. Arthroplasty

Overview

Femoral neck fractures represent a major public health burden, particularly in the elderly osteoporotic population. The critical decision in managing these injuries is whether to preserve the native femoral head through internal fixation or to replace it with an arthroplasty. This decision hinges on patient age, activity level, fracture displacement, bone quality, and the vascularity of the femoral head. Timing of surgery matters as well: early fixation reduces the risk of avascular necrosis, while early arthroplasty reduces medical complications associated with prolonged immobility.

Anatomy and Blood Supply

Femoral Neck Anatomy

The femoral neck connects the femoral head to the intertrochanteric region, with approximately 10 to 15 degrees of anteversion and a neck-shaft angle of roughly 125 to 135 degrees. Critically, the femoral neck is intracapsular, meaning fractures at this level disrupt the synovial environment and compress the retinacular vessels that supply the femoral head.

Blood Supply to the Femoral Head

The medial femoral circumflex artery (MFCA) provides approximately 80% of the blood supply to the femoral head. It courses posteriorly between the iliopsoas and pectineus muscles and gives rise to superior and inferior retinacular arteries. The lateral epiphyseal artery, a branch of the MFCA, is the dominant supply to the weight-bearing dome. The lateral femoral circumflex artery (LFCA) makes a minor contribution through anterior retinacular vessels, and the ligamentum teres artery, a branch of the obturator artery, provides minimal supply in adults but is more important in children. Displaced femoral neck fractures kink or tear these retinacular vessels, causing femoral head ischemia.

<image>Blood supply to the femoral head showing the medial femoral circumflex artery and retinacular vessel system</image>

Classification

Garden Classification

The Garden classification divides femoral neck fractures into four types. Type I fractures are incomplete or valgus impacted with angulated trabeculae. Type II fractures are complete but nondisplaced with aligned trabeculae. Type III fractures are complete and partially displaced, with trabecular malalignment and the femoral head in varus. Type IV fractures are complete and fully displaced, with the femoral head free in the acetabulum. In practice, the classification is simplified into nondisplaced (Garden I and II) versus displaced (Garden III and IV), because interobserver reliability is poor for distinguishing individual types but acceptable for this simplified dichotomy.

Pauwels Classification (by Fracture Angle)

The Pauwels classification categorizes fractures by the angle of the fracture line relative to the horizontal. Type I fractures have an angle less than 30 degrees, subjecting them mostly to compression forces and making them stable. Type II fractures fall between 30 and 50 degrees with mixed forces. Type III fractures exceed 50 degrees, making the fracture line more vertical and subjecting it predominantly to shear forces, which renders it unstable. A higher Pauwels angle corresponds to a higher risk of nonunion with fixation.

AO/OTA Classification

In the AO/OTA system, 31B1 denotes a subcapital nondisplaced fracture, 31B2 a transcervical fracture, and 31B3 a subcapital displaced fracture.

Diagnosis

Clinical Presentation

In the elderly, the typical presentation is a fall from standing height resulting in groin pain and inability to bear weight. In young patients, the mechanism is usually high-energy, such as a motor vehicle accident or fall from height. Displaced fractures produce a characteristically shortened and externally rotated limb. Nondisplaced or impacted fractures may allow the patient to walk with pain, making them easily missed.

Imaging

Standard imaging includes an AP pelvis and a cross-table lateral of the hip. MRI is the gold standard for detecting occult fractures, with sensitivity exceeding 99% within 24 hours, and is indicated when radiographs are negative but clinical suspicion remains high. CT is an alternative if MRI is unavailable or contraindicated. Bone scan is a historical alternative that is less sensitive in the first 48 to 72 hours.

Treatment

Nondisplaced Fractures (Garden I-II)

Internal fixation is appropriate for all age groups with nondisplaced fractures. The standard technique uses three parallel cannulated screws (6.5 or 7.0 mm) in an inverted triangle configuration. The inferior screw is placed along the calcar and is the most important because it resists varus. The posterior screw follows the posterior cortex, and the anterior-superior screw completes the triangle. All screws should have threads crossing the fracture but must not protrude into the joint. The starting point is the lateral cortex at or below the lesser trochanter. Reduction is usually anatomic or valgus-impacted; importantly, surgeons should not attempt to reduce valgus-impacted fractures because doing so risks displacing them. Nonunion rates are 5 to 8%, and AVN rates are 8 to 15%. A dynamic hip screw with a derotation screw is an alternative for basicervical fractures, which behave more like intertrochanteric fractures biomechanically.

Displaced Fractures (Garden III-IV)

Young Patients (<60 years)

In young patients, the goal is to preserve the native femoral head through urgent anatomic reduction and internal fixation. Reduction and fixation should ideally occur within 6 to 12 hours to minimize AVN risk, although the evidence on the exact time threshold continues to evolve. Reduction may be closed or open, and fixation options include cannulated screws or a sliding hip screw with a derotation screw. Capsulotomy to decompress the intracapsular hematoma and improve perfusion is controversial but increasingly practiced. Despite timely fixation, AVN develops in 15 to 30% of cases and nonunion in 10 to 20%, with an overall reoperation rate of 30 to 40%.

Elderly, Low-Demand Patients (>60-65 years)

Arthroplasty is the standard of care for displaced fractures in this population, as it avoids the high nonunion and AVN rates seen with internal fixation in osteoporotic bone.

Hemiarthroplasty (HA)

Hemiarthroplasty replaces the femoral head while retaining the native acetabulum. It is available in unipolar (single articulation) and bipolar (dual articulation) designs; the theoretical advantage of bipolar bearings in reducing acetabular erosion has not translated into a meaningful clinical difference. Cemented fixation is preferred in elderly osteoporotic bone because it carries a lower risk of periprosthetic fracture and revision, a finding supported by multiple randomized controlled trials. Modern cementing techniques include a cement restrictor, retrograde filling, and pressurization. Approach options include posterior, anterolateral, and direct anterior. Hemiarthroplasty is indicated for lower-demand elderly patients, those with limited life expectancy, and patients with significant cognitive impairment.

Total Hip Arthroplasty (THA)

Total hip arthroplasty replaces both the femoral head and the acetabulum. Compared with hemiarthroplasty, THA offers a lower revision rate, better functional outcomes as measured by the Harris Hip Score, and lower risk of acetabular erosion. However, it carries a higher dislocation risk (especially with the posterior approach), longer operative time, and greater blood loss. THA is indicated for active elderly patients with displaced femoral neck fractures, patients with pre-existing acetabular pathology such as arthritis, and those with a longer life expectancy.

<image>Comparison of cannulated screw fixation, hemiarthroplasty, and total hip arthroplasty for femoral neck fractures</image>

Key Trials

HEALTH Trial (2019)

The HEALTH trial was a multicenter randomized controlled trial comparing THA with HA for displaced femoral neck fractures in patients over 50 years. The primary outcome was secondary hip procedure within 24 months. The result showed no significant difference in revision rate between THA (7.9%) and HA (8.1%). THA produced slightly better functional scores, but the difference was not clinically significant. The interpretation is that both options are reasonable, and patient selection is what matters most.

FAITH Trial (2017)

The FAITH trial compared cancellous screws with sliding hip screws for femoral neck fractures and found no significant difference in reoperation rates. A sliding hip screw may be preferred for vertical (Pauwels III) fractures.

Basicervical Fractures

Basicervical fractures occur at the base of the femoral neck, along the intertrochanteric line. They behave biomechanically like intertrochanteric fractures because of the high shear forces involved. Treatment consists of a sliding hip screw with a derotation screw or a cephalomedullary nail; cannulated screws alone have an unacceptably high failure rate for this pattern.

Timing of Surgery

The general consensus is that surgery should occur within 24 to 48 hours of admission, with medical optimization as indicated. Delays beyond 48 hours are associated with increased mortality, delirium, pressure injuries, and pneumonia. In young patients with displaced fractures, emergent or urgent fixation within 6 to 12 hours is favored by most surgeons to maximize femoral head viability, though this timing remains debated. Preoperative anticoagulant management should not excessively delay surgery.

Complications

Avascular Necrosis (AVN)

AVN is the most feared complication of femoral head preservation. The risk is proportional to displacement, time to reduction, and quality of reduction. It presents months to years after fixation and is staged using the Ficat or Steinberg classification. Treatment ranges from core decompression for early disease to vascularized fibular grafting and THA for late or collapsed stages.

Nonunion

Risk factors for nonunion include displacement, varus reduction, inadequate fixation, smoking, and a vertical fracture pattern. Treatment options include THA or revision fixation with a valgus intertrochanteric osteotomy in young patients.

Femoral Neck Shortening After Fixation

Progressive shortening at the fracture site occurs as screws slide, potentially causing abductor weakness and limp. This can be mitigated by using fully-threaded screws (which prevent sliding but risk cutting out) or length-stable fixation constructs such as fixed-angle devices.

<image>Garden classification of femoral neck fractures showing Types I through IV on AP radiographs</image>

Clinical Pearls

Always obtain both an AP pelvis and a cross-table lateral radiograph, as the lateral view helps assess posterior comminution and displacement. In elderly patients who present ambulatory with hip or groin pain after a fall and negative radiographs, obtain an MRI, because occult femoral neck fractures are common and missing them leads to displacement. Valgus-impacted (Garden I) fractures in elderly patients can be treated with internal fixation even in the very old; do not automatically default to arthroplasty for nondisplaced fractures. In young patients, anatomic reduction is critical and nothing less should be accepted; open reduction is warranted if closed reduction is inadequate. Cemented hemiarthroplasty is the standard for elderly patients, as the evidence strongly favors cementing over press-fit in osteoporotic bone. Perioperative mortality for hip fractures remains approximately 5 to 10% at 30 days and 20 to 30% at 1 year, reflecting the fragility of this population rather than the surgery itself. Orthogeriatric co-management models with shared care from geriatrics reduce complications, length of stay, and mortality.

References

• Garden RS. Low-angle fixation in fractures of the femoral neck. J Bone Joint Surg Br. 1961;43(4):647-663.
• Bhandari M, et al. Total hip arthroplasty or hemiarthroplasty for hip fracture (HEALTH trial). N Engl J Med. 2019;381(23):2199-2208.
• Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) Investigators. Lancet. 2017;389(10078):1519-1527.
• Slobogean GP, et al. Complications following young femoral neck fractures. Injury. 2015;46(3):484-491.
• Pauwels F. Der Schenkelhalsbruch, ein mechanisches Problem. Z Orthop Ihre Grenzgeb. 1935;63:1-138.
• Ly TV, Swiontkowski MF. Treatment of femoral neck fractures in young adults. JBJS Am. 2008;90(10):2254-2266.

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