Continuing Education Activity

Hip fractures are common injuries. Femoral neck fractures are a specific type of intracapsular hip fracture. The femoral neck connects the femoral shaft with the femoral head. The hip joint is the articulation of the femoral head with the acetabulum. The junctional location makes the femoral neck prone to fracture. The blood supply of the femoral head runs along the femoral neck and is an essential consideration in displaced fractures and patients in the younger population. This activity reviews the etiology, presentation, evaluation, and management of femoral neck fractures and reviews the role of the interprofessional team in evaluating, diagnosing, and managing the condition.

Objectives:

• Review the mechanisms of injury leading to femoral neck fractures, and identify the at-risk patient populations.
• Summarize the diagnostic approach for evaluation and assessment of a patient presenting with a potential femoral neck fracture, including any indicated imaging studies and potential differentials.
• Outline the treatment options for the reduction of femoral neck fractures, depending on patient population and fracture severity and location.
• Describe some interprofessional team strategies for improving communication to advance medical care and improve outcomes for femoral neck fractures.

Introduction

Hip fractures are common injuries, especially seen in the elderly in the emergency setting. It is also seen in young patients who perform in athletics or high-energy trauma. Immediate diagnosis and management are required to prevent threatening joint complications.[1] In the United States, the economic burden of hip fractures is amongst the top 20 expensive diagnoses, with approximately 20 billion dollars spent on the management of this injury.[2][3][4] It is estimated there will be approximately 300,000 cases of hip fractures annually in the United States by the year 2030.[5] 

Femoral neck fractures are a specific type of intracapsular hip fracture. The femoral neck connects the femoral shaft with the femoral head. The hip joint is the articulation of the femoral head with the acetabulum. The junctional location makes the femoral neck prone to fracture. The blood supply of the femoral head is an essential consideration in displaced fractures as it runs along the femoral neck.

Etiology

Femoral neck fractures are associated with low energy falls in the elderly. In younger patients sustaining a femoral neck fracture, the cause is usually secondary to high-energy trauma such as a substantial height or motor vehicle accidents.[6][7] Risk factors for femoral neck fractures include female gender, decreased mobility, and low bone density.[8][9][8]

Epidemiology

There are approximately 1.6 million hip fractures annually. Seventy percent of all hip fractures occur in women. Hip fracture risk increases exponentially with age and is more common in white females.[7][10] 

Pathophysiology

The chief source of vascular supply to the femoral head is the medial femoral circumflex artery, which runs under the quadratus femoris. 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.[11] This is most important when considering the younger population that sustains this fracture, for which arthroplasty would be inappropriate.[12] In patients treated via open reduction internal fixation, avascular necrosis is the most common complication.[13]

History and Physical

In the majority of cases, the patient will have had recent trauma. In cases of dementia or cognitive impairment, the history may be scant without the report of any trauma. This is where obtaining an account from the nursing home, or health aids is crucial. Question the nurse aids of any recent falls and change in cognition the past few days. The patient will complain of pain with a decreased range of motion of the hip. In non-displaced fractures, there may be no deformity. However, displaced fractures may present with a shortened and externally rotated lower limb.

The patient history varies depending on the mechanism of injury. The following should be obtained during the history and physical examination:

• Low energy trauma - the mechanism is essential, and the events around the fall should be questioned to rule out any possible syncopal cause for fall.
• High energy trauma - Follow the ATLS (Adult Trauma Life Support) protocol when indicated. Assess for any non-orthopedic emergent injuries first and then ipsilateral injuries, including femur fracture or knee injury. For high vertical falls, inspect the ankle for any abnormalities.
• Important pertinent medical history: Baseline function and activity level, use of ambulatory aids before the injury, blood thinners, history of cancer, pulmonary embolism, and deep venous thrombosis.

Evaluation

The provider should perform a complete neurovascular examination of the affected extremity. The following imagining should be ordered when indicated:

• Plain films: radiographs-anterior-posterior (AP) pelvis, AP and lateral hip, AP and lateral femur, AP and lateral knee.
• Computed tomography (CT) scan - helps better classify the fracture pattern or delineate a subtle fracture line. It is part of the trauma assessment and can be extended to include the femoral neck.
• Magnetic resonance imaging (MRI) - not generally used in the acute setting but may be used to evaluate for femoral neck stress fractures.

Medical assessment should include basic labs (complete blood count, basal metabolic panel, and prothrombin/international normalized ratio, if applicable) as well as a chest radiograph and electrocardiogram (EKG). Elderly patients with known or suspected cardiac disease may benefit from preoperatively cardiology evaluation. Preoperative medical optimization is vital in the geriatric population.

There are many classifications for femoral neck fracture, including the most common clinical classifications by Garden and Pauwel, which includes the following[12][14]

The 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

The Garden classification is the most used system used to communicate the type of fracture. For treatment, it is often simplified into nondisplaced (Type 1 and Type 2) versus displaced (Type 3 and Type 4).[14]

Pauwel Classification

The Pauwel classification also includes the inclination angle of the fracture line relative to the horizontal. Higher angles and more vertical fractures exhibit greater instability due to higher shear force.  These fractures also have a higher risk of osteonecrosis postoperatively.

• Type I     less than 30 degrees
• Type II    30 to 50 degrees
• Type III   greater than 50 degrees

Treatment / Management

Non-operative

Non-operative management for these fractures is rarely the treatment course. It is only potentially useful for non-ambulatory, comfort care, or extremely high-risk patients.

Operative

Young patients with femoral neck fractures will require treatment with emergent open reduction internal fixation.[6][15] Vertically oriented fractures such a Pauwel III type fractures are more common in younger and high-energy trauma patients. A sliding hip screw is biomechanically more stable for these fracture patterns. With displaced fractures in younger patients, the goal is to achieve anatomic reduction through emergent open-reduction internal fixation.[15]

Non-displaced fractures are treated typically with percutaneous cannulated screws or a sliding hip screw. However, there a higher rate of avascular necrosis (AVN) with the use of a sliding hip screw (9%) compared to cannulated screws (4%).[16]

With displaced fractures of the femoral neck in elderly patients, the treatment depends on the patient's baseline activity level and age. Less active individuals may receive a hemiarthroplasty.[17] More active individuals are treated with total hip arthroplasty. Total hip arthroplasty is a more resilient procedure, but it also carries an increased risk of dislocation when compared to a hemiarthroplasty.[18][19][15]

Summary of Operative Methods

Young Patients (less than 60)

• Open-reduction internal fixation 

Elderly Patients

Non-displaced

• Percutaneous cannulated screws or sliding hip screw

Displaced

• Hemiarthroplasty-less active patients 
• Total hip arthroplasty-active patients

Differential Diagnosis

• Hip dislocation - displacement of the femoral head from the acetabulum
• Intertrochanteric fracture - the fracture line is more distal and lies between the greater and lesser trochanter
• Subtrochanteric fracture - the fracture line is within 5 cm distal to the lesser trochanter
• Femur fracture - the fracture line is within the femoral diaphysis
• Osteoarthritis - pain that is more chronic. Usually, patients complain of groin pain. Pain that worsens with activity or stairs

Prognosis

After femoral neck fracture, there is a 6% in-house mortality rate. There is a 1-year mortality rate between 20-30%, with the highest risk within the first six months.[2][20] Overall with hip fractures, 51% will resume independent ambulation while 22% will remain non-ambulatory.[21]

Complications

• Avascular necrosis increased risk factor with increased initial displacement and failure to obtain an anatomical reduction[13]
• Nonunion
• Dislocation increased with total hip arthroplasty surgery

Postoperative and Rehabilitation Care

Patients treated with a total hip arthroplasty or hemiarthroplasty should be weight-bearing as tolerated postoperatively.[22] They should observe hip precautions depending on the surgical approach used for the procedures. Deep venous thrombosis prophylaxis should be started during the perioperative period and continued for 4 to 6 weeks postoperatively. Physical therapy should begin immediately after surgery.

Deterrence and Patient Education

Preoperatively, patients should be educated on the limitations on hip movements they may have due to the prosthesis. In addition, emphasis should be placed on proper activities of daily living such as sitting on the toilet, climbing stairs, and sitting and standing from a seated position after surgery.

Pearls and Other Issues

• Young patients with femoral neck fractures should be treated emergently for stabilization via open reduction internal fixation after completion of imaging and ATLS protocol as needed. With more vertically oriented fractures such a Pauwel III, a sliding hip screw is biomechanically stable.
• Elderly patients should be seen and evaluated by medical services and optimized as needed.
• Displacement and baseline activity dictate the treatment plan.
• A non-displaced fracture may have surgical treatment with screws in situ.
• A displaced fracture may undergo a total hip arthroplasty in active individuals or a hemiarthroplasty in less active individuals.

Enhancing Healthcare Team Outcomes

Most patients with a femoral neck fracture will present to the emergency department. Obtain the proper injury radiograph films and history from the patient. With the identification of a femoral neck injury, the patient should immediately become non-weight bearing. From a triage standpoint, the younger patients that benefit from joint sparing fixation should promptly obtain a referral to orthopedics.

For elderly patients, it is vital to identify medical comorbidities. These patients should be medically optimized before operative treatment. Especially in females, it is often painful to urinate, so the placement of a Foley catheter for comfort within the emergency department may be necessary and discontinued postoperatively with ambulation. In the orthopedic unit, it is essential to note the operative approach used because it dictates the post-operative precautions the patient should maintain. For example, for a posterior approach, the patient typically has an abduction pillow to sleep with at night. Posterior precautions also include not crossing the legs, leaning forward while seated, and letting the toes point inward. These precautions help prevent dislocation. Physical therapy and mobilization postoperatively are essential to help patients return to function.

Patients that suffer a femoral neck fracture can benefit from preoperative evaluation and postoperative management of their comorbidities. This interprofessional care team may include orthopedics, geriatrics, internal medicine, trauma surgery, anesthesia, cardiology, operating room and orthopedic nurses, physical therapists, and any other subspecialty that may help manage the patient’s comorbidities.