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.
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.Risk factors for femoral neck fractures include female gender, decreased mobility, and low bone density.
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. This is most important when considering the younger population that sustains this fracture for which arthroplasty would be inappropriate. In patients treated via open reduction internal fixation, avascular necrosis is the most common complication.
Typically, the patient will have had recent trauma, however, in cases of dementia or cognitive impairment, there may be no history of trauma. The patient will have pain with a decreased range of motion of the hip. In a non-displaced fracture, there may be no deformity whereas displaced fractures can present with a shortened and externally rotated hip.
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 protocol when indicated. Assess for any non-orthopedic injuries first and then ipsilateral injuries including femur fracture or knee injury.
Important pertinent medical history: Baseline function and activity level, baseline use of ambulatory aids, use of blood thinners, history of cancer, history of PE/ DVTs.
The physician should perform a complete neurovascular exam of the affected extremity.
Imaging: radiographs-AP pelvis, AP and lateral hip, AP and lateral femur, AP and lateral knee.
CT scans - help better characterize the fracture pattern or delineate a subtle fracture line, often included in part of a trauma assessment and can be extended to include the femoral neck.
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 (CBC, BMP, and PT/INR if applicable) as well as a chest radiograph and EKG. Elderly patients with known or suspected cardiac disease may benefit from preoperatively cardiology evaluation. Preoperative medical optimization is vital in the geriatric population.
The Garden classification:
The Garden classification is the most used system used to communicate the type of fracture. For treatment, it is often simplified into non-displaced (Type 1 and Type 2) versus displaced (Type 3 and Type 4)
The Pauwel classification also includes the inclination angle of the fracture line relative to the horizontal. Higher angle and more vertical fractures exhibit greater instability due to higher shear force. These fractures also have a higher risk of osteonecrosis postoperatively.
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.
Young patients with femoral neck fractures will require treatment with emergent open reduction internal fixation. Vertically oriented fractures such a Pauwel III type fractures are more common in the younger population 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.
Non-displaced fractures are treated with typically with percutaneous cannulated screws or a sliding hip screw. However, there a higher rate of AVN with use of sliding hip screw (9%) compared to cannulated screws (4%).
With displaced fractures of the femoral neck in elderly patients, the treatment depends on the patient baseline activity level and their age. Displaced fractures in the elderly are the treatment depends on activity level. Less active individuals may receive a hemiarthroplasty. 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 hemiarthroplasty.
Summary of Operative methods:
Young patients (<60):
Patients treated with a total hip arthroplasty or hemiarthroplasty should be weight bearing as tolerated postoperatively. They should observe hip precautions depending on the surgical approach used for the procedures. DVT prophylaxis should be started during the perioperative period and continued for 4-6 weeks postoperatively. Physical therapy should begin immediately after surgery.
Patients that suffer a femoral neck fracture can benefit from preoperative evaluation and postoperative management of their comorbidities. This multidisciplinary care team may include orthopedics, geriatric, internal medicine, trauma surgery, anesthesia, cardiology, and any other subspecialty that may help manage the patient’s comorbidities.
Most patients with a femoral neck fracture will present to the emergency room. One should obtain the proper injury x-ray 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 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 prior to operative treatment. Especially in females, it is often painful to urinate, so placement of a Foley catheter for comfort within the emergency room may be necessary and discontinued postoperatively with ambulation. On the orthopedic unit, it is important 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 post-operatively is essential to help patients return to function.