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Femoral neck fracture

Femoral neck fracture

Femoral neck fracture also called neck of femur fracture, is a specific type of intracapsular hip fracture. Femoral neck fractures are common injuries sustained by older patients who are both more likely to have unsteadiness of gait and reduced bone mineral density, predisposing to fracture. Elderly osteoporotic women are at greatest risk. The femoral neck connects the femoral shaft with the femoral head. The femoral neck is the weakest part of the femur. 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.

In general, femoral neck fractures occur in 2 distinct populations, (1) young, active individuals with unaccustomed strenuous activity or changes in activity, such as runners or endurance athletes, and (2) elderly individuals with osteoporosis 1.

Femoral neck fractures in young patients are usually caused by high-energy trauma. These fractures are often associated with multiple injuries and high rates of avascular necrosis and nonunion. Results of this injury depend on (1) the extent of injury (ie, amount of displacement, amount of comminution, whether circulation has been disturbed), (2) the adequacy of the reduction, and (3) the adequacy of fixation. Recognition of the disabling complications of femoral neck fractures requires meticulous attention to detail in their management.

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 Caucasian females 2.

Hip anatomy

The hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is the femoral head, which is the upper end of the femur (thighbone).

A smooth tissue called articular cartilage covers the surface of the ball and the socket. It creates a low friction surface that helps the bones glide easily across each other.

The acetabulum is ringed by strong fibrocartilage called the labrum. The labrum forms a gasket around the socket, creating a tight seal and helping to provide stability to the joint.

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 3. In patients treated via open reduction internal fixation, avascular necrosis is the most common complication 4.

Figure 1. Hip joint anatomy (in a healthy hip, the head of the femur stays firmly within the acetabulum)

Hip anatomy

Figure 2. Femoral neck fracture

neck of femur fracture

Neck of femur fracture types

Femoral neck fractures are a subset of proximal femoral fractures.

Since disruption of blood supply to the femoral head is dependent on the type of fracture and causes significant morbidity, diagnosis and classification of these fractures is important. There are three types:

  1. Subcapital femoral neck fracture: femoral head/neck junction
  2. Transcervical femoral neck fracture: midportion of femoral neck
  3. Basicervical femoral neck fracture: base of femoral neck

Most significantly, subcapital and transcervical fractures are considered intracapsular while basicervical fractures are considered extracapsular 5.

Further, severity of a subcapital fracture is graded by the Garden classification of hip fractures.

Figure 3. Neck of femur fracture types

femoral neck fracture types

Garden classification of subcapital femoral neck fracture

There are many classifications for femoral neck fracture including the most common clinical classifications by Garden and Pauwel 6. The Garden classification of subcapital femoral neck fractures is the most widely used. It is simple and predicts the development of avascular necrosis 7. Garden described particular femoral neck and acetabular trabeculae patterns which can assist in recognizing differences within this classification system 8.

  • Garden stage 1: undisplaced incomplete, including valgus impacted fractures. Medial group of femoral neck trabeculae may demonstrate a greenstick fracture
  • Garden stage 2: undisplaced complete. No disturbance of the medial trabeculae
  • Garden stage 3: complete fracture, incompletely displaced. Femoral head tilts into a varus position causing its medial trabeculae to be out of line with the pelvic trabeculae
  • Garden stage 4: complete fracture, completely displaced. Femoral head aligned normally in the acetabulum and its medial trabeculae are in line with the pelvic trabeculae

In general, Garden stage 1 and 2 are stable fractures and can be treated with internal fixation (head-preservation) and stage 3 and 4 are unstable fractures and hence treated with arthroplasty (either hemi- or total arthroplasty) 9.

Figure 4. Garden classification femoral neck fracture

Garden classification neck of femur fracture

Pauwel classification of femoral neck fracture

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.

  • Type 1: <30 degrees
  • Type 2: 30-50 degrees
  • Type 3: >50 degrees

Figure 5. Pauwel classification of femoral neck fracture 

Femoral neck fracture causes

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 2. Risk factors for femoral neck fractures include female gender, decreased mobility, and low bone density 10.

Femoral neck fracture prevention

Patient education is an important factor in the prevention of stress fractures. Female athletes should decrease their risk of recurrent fractures by maintaining adequate muscle mass and bone density.

Maintaining proper flexibility is also thought to play a significant role in the prevention of sports-related injuries. Additionally, improvement in aerobic fitness can increase blood flow and oxygenation to all tissues, including the muscles and bones, and it would be a reasonable addition to any rehabilitation and prevention program. Seasonal athletes should be encouraged to cross-train all year or at least undergo preconditioning before participating in their particular sport.

Femoral neck fracture symptoms

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.

History:

  • 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 Advanced Trauma Life Support (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 pulmonary embolism or deep vein thrombosis (DVT).

Femoral neck fracture complications

  • Avascular necrosis increased risk factor with increased initial displacement and failure to obtain an anatomical reduction 4
  • Nonunion
  • Dislocation increased with total hip arthroplasty treatment

Femoral neck fracture diagnosis

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.

Femoral neck fracture treatment

The goals of treatment in patients with femoral neck fractures are to promote healing, to prevent complications, and to return function. The primary goal of fracture management is to return the patient to his or her premorbid level of function. This is completed with either surgical or nonsurgical management. Several factors must be considered before a treatment plan is recommended. The decision for operative or nonoperative treatment of femoral neck fractures and the decision regarding the type of surgical intervention are based on many factors 11.

Tension fractures are potentially unstable and may require operative stabilization. Nondisplaced femoral neck fractures may need to be stabilized with multiple parallel lag screws or pins.

The treatment of a displaced fracture is based on the person’s age and activity level. In the elderly population, premorbid cognitive function, walking ability, and independence in activities of daily living should be considered when determining the optimal method of surgical repair.

Compression fractures are more stable than tension-type fractures, and they can be treated nonoperatively. Treatment for nondisplaced fractures is bed rest and/or the use of crutches until passive hip movement is pain free and x-ray films show evidence of callus formation. Patients should be monitored closely with serial x-ray films, because the risk of displacement of the fracture is high. Immediate open reduction and internal fixation is indicated if the fracture widens.

A displaced fracture in a young patient is an orthopedic emergency, and early open reduction and internal fixation is necessary. The prognosis for returning to a high level of sport participation is poor in this situation. In elderly patients, treatment options include open reduction and internal fixation or prosthetic replacement.

The decision between these options should be made on an individual basis. A series of studies by Blomfeldt et al demonstrated that total hip replacement in elderly patients with higher cognitive function and a more independent lifestyle was associated with a significantly lower complication and reoperation rate 12. Additionally, health-related quality of life was superior at 2 years and equal at 4 years when compared with patients treated with internal fixation. Conversely, neither total hip replacement nor internal fixation was found to be advantageous in patients with severe cognitive impairment. Both prosthetic replacement and internal fixation were associated with a high rate of mortality and decreased functioning in activities of daily living.

In patients with an overt fracture line and no displacement on x-ray films, the initial treatment is complete non–weight-bearing ambulation with crutches. The clinician should obtain an x-ray film every 2-3 days the first week to detect any extension or widening of the fracture line. If pain does not resolve or if evidence of fracture line expansion is noted, internal fixation is indicated. In patients with a positive bone scan result and no visible fracture line on the x-ray film, the initial treatment is proportional to the severity of the symptoms. Treatment begins with non–weight-bearing or partial weight-bearing (based on symptoms) activities with crutches until symptoms resolve.

Most complications are associated with fracture displacement or a delay in diagnosis. Complications include delayed union, nonunion, refracture, osteonecrosis, and avascular necrosis. Early fixation failure (within 3 months of surgery) occurs in 12-24% of displaced femoral neck fractures treated by internal fixation.

In a long-term study that followed elderly patients treated with internal fixation, Blomfeldt et al 12 reported a hip complication rate of 42% and a reoperation rate of 47% at 48 months. Stappaerts 13 found that the most important factors associated with loss of fixation were advanced age and inaccurate reduction.

Scheck 14 emphasized the importance of posterior comminution of the femoral neck as a cause of fixation failure and nonunion. Additionally, Heetveld et al 15 reported that no difference was noted between osteopenic and osteoporotic patients treated with internal fixation when considering revision to arthroplasty.

Non-surgical treatment

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

If the nonoperative approach is taken, the patient should be mobilized as soon as possible to avoid the complications of prolonged immobilization.

Surgical treatment

Young patients with femoral neck fractures will require treatment with emergent open reduction internal fixation 16. Vertically oriented fractures such a Pauwel 3 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 16.

Non-displaced fractures are treated with typically with percutaneous cannulated screws or a sliding hip screw. However, there a higher rate of avascular necrosis with use of sliding hip screw (9%) compared to cannulated screws (4%) 17.

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 18. 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 19.

Summary of surgical methods

  • Young patients (<60 years of age): Open-reduction internal fixation
  • Elderly patients (>60 years of age):
    • Non-displaced femoral neck fracture: Percutaneous cannulated screws or sliding hip screw
    • Displaced femoral neck fracture:
      • Hemiarthroplasty- less active patients
      • Total hip arthroplasty- active patients

Wang et al 20 conducted a meta-analysis of randomized controlled trials comparing the outcomes of bipolar hemiarthroplasty with total hip arthroplasty for treating femoral neck fractures in healthy elderly patients. The study concluded that for healthy elderly patients with displaced femoral neck fractures, treatment with bipolar hemiarthroplasty led to better outcomes regarding dislocation rate, while total hip arthroplasty was better regarding acetabular erosion rate and reoperation rate 20.

Rehabilitation

Once the painful symptoms of a stable femoral neck fracture are controlled during the acute phase of treatment, strengthening exercises for the hip stabilizers and associated muscles can be initiated. The main objectives are to improve and restore range of motion of the hip.

Once the patient is pain free, weight bearing can be progressed. When patients are able to tolerate partial weight-bearing ambulation, general conditioning workouts, including swimming and cycling, are permitted. Serial x-ray films are obtained at weekly intervals until the patient can ambulate with full weight bearing and no pain.

Running is gradually reintroduced, and progression of distance is slow. If pain occurs, a couple of days of rest are recommended, mileage is reduced, and then mileage is progressed again depending on the individual’s symptoms.

Surgery is indicated for patients with overt fractures or displacement on the tension side. Usually, fixation with a plate and screws is used. Postoperatively, the patient rests until pain resolves and then progresses to full activity as healing occurs. Once the plate is removed, further rehabilitation is needed. Removal of the plate depends on the age and activity level of the patient. Some patients prefer weight bearing with crutches. Patients are usually allowed to return to running; however, contact sports are limited.

Strengthening of the gluteus medius, a hip abductor, is important for postoperative stability. Other important muscles include the iliopsoas; gluteus maximus; adductor magnus, longus, and brevis; quadriceps; and hamstrings. Functional goals include normalizing the patient’s gait pattern. Activities are then progressed to sport-specific training and strengthening.

Maintaining aerobic conditioning throughout the rehabilitation process is important. If protected or non–weight-bearing ambulation is necessary, then upper body exercise, such as an upper body ergometer, can be used. Once partial weight-bearing ambulation is allowed, aquatic training may be used, such as swimming or deep-water running.

Patients treated with a total hip arthroplasty or hemiarthroplasty should be weight bearing as tolerated postoperatively 21. 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.

Femoral neck fracture 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 22. Overall with hip fractures, 51% will resume independent ambulation while 22% will remain non-ambulatory 23. A displaced stress fracture of the femoral neck may end the career of an elite athlete even if correctly treated. Early diagnosis and treatment may prevent displacement of the fracture and thus improve the prognosis.

References
  1. Konetsky M, Miller J, Tripp C. Femoral neck stress fracture. J Orthop Sports Phys Ther. 2013 Apr. 43(4):275.
  2. Johnell O, Kanis JA. An estimate of the worldwide prevalence and disability associated with osteoporotic fractures. Osteoporos Int. 2006 Dec;17(12):1726-33.
  3. Li M, Cole PA. Anatomical considerations in adult femoral neck fractures: how anatomy influences the treatment issues? Injury. 2015 Mar;46(3):453-8.
  4. Dedrick DK, Mackenzie JR, Burney RE. Complications of femoral neck fracture in young adults. J Trauma. 1986 Oct;26(10):932-7.
  5. Khurana B, Mandell JC, Rocha TC, Duran-Mendicuti MA, Jimale H, Rosner B, Harris MB, Sodickson AD, Weaver MJ. Internal Rotation Traction Radiograph Improves Proximal Femoral Fracture Classification Accuracy and Agreement. (2018) AJR. American journal of roentgenology. 211 (2): 409-415. doi:10.2214/AJR.17.19258 https://www.ajronline.org/doi/full/10.2214/AJR.17.19258
  6. Kazley JM, Banerjee S, Abousayed MM, Rosenbaum AJ. Classifications in Brief: Garden Classification of Femoral Neck Fractures. Clin. Orthop. Relat. Res. 2018 Feb;476(2):441-445.
  7. Garden RS. Low-angle fixation in fractures of the femoral neck. Bone & Joint Journal. 43-B (4): 647.
  8. Garden RS. Stability and union in sub capital fractures of the femur. Bone & Joint Journal. 46-B (4): 630.
  9. Mears SC. Classification and surgical approaches to hip fractures for nonsurgeons. Clin. Geriatr. Med. 2014;30 (2): 229-41. doi:10.1016/j.cger.2014.01.004
  10. Cummings SR, Black DM, Nevitt MC, Browner W, Cauley J, Ensrud K, Genant HK, Palermo L, Scott J, Vogt TM. Bone density at various sites for prediction of hip fractures. The Study of Osteoporotic Fractures Research Group. Lancet. 1993 Jan 09;341(8837):72-5.
  11. Moroni A, Hoque M, Waddell JP, Russell TA, Wippermann B, Digiovanni G. Surgical treatment and management of hip fracture patients. Arch Orthop Trauma Surg. 2011 Dec 6.
  12. Blomfeldt R, Tornkvist H, Ponzer S, Soderqvist A, Tidermark J. Internal fixation versus hemiarthroplasty for displaced fractures of the femoral neck in elderly patients with severe cognitive impairment. J Bone Joint Surg Br. 2005 Apr. 87(4):523-9.
  13. Stappaerts KH. Early fixation failure in displaced femoral neck fractures. Arch Orthop Trauma Surg. 1985. 104(5):314-8.
  14. Scheck M. The significance of posterior comminution in femoral neck fractures. Clin Orthop Relat Res. 1980 Oct. 152:138-42.
  15. Heetveld MJ, Raaymakers EL, van Eck-Smit BL, van Walsum AD, Luitse JS. Internal fixation for displaced fractures of the femoral neck. Does bone density affect clinical outcome?. J Bone Joint Surg Br. 2005 Mar. 87(3):367-73.
  16. Bhandari M, Devereaux PJ, Swiontkowski MF, Tornetta P, Obremskey W, Koval KJ, Nork S, Sprague S, Schemitsch EH, Guyatt GH. Internal fixation compared with arthroplasty for displaced fractures of the femoral neck. A meta-analysis. J Bone Joint Surg Am. 2003 Sep;85-A(9):1673-81.
  17. Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) Investigators. Fracture fixation in the operative management of hip fractures (FAITH): an international, multicentre, randomised controlled trial. Lancet. 2017 Apr 15;389(10078):1519-1527.
  18. Rogmark C, Leonardsson O. Hip arthroplasty for the treatment of displaced fractures of the femoral neck in elderly patients. Bone Joint J. 2016 Mar;98-B(3):291-7.
  19. Avery PP, Baker RP, Walton MJ, Rooker JC, Squires B, Gargan MF, Bannister GC. Total hip replacement and hemiarthroplasty in mobile, independent patients with a displaced intracapsular fracture of the femoral neck: a seven- to ten-year follow-up report of a prospective randomised controlled trial. J Bone Joint Surg Br. 2011 Aug;93(8):1045-8.
  20. Wang F, Zhang H, Zhang Z, Ma C, Feng X. Comparison of bipolar hemiarthroplasty and total hip arthroplasty for displaced femoral neck fractures in the healthy elderly: a meta-analysis. BMC Musculoskelet Disord. 2015 Aug 28. 16:229.
  21. Koval KJ, Friend KD, Aharonoff GB, Zukerman JD. Weight bearing after hip fracture: a prospective series of 596 geriatric hip fracture patients. J Orthop Trauma. 1996;10(8):526-30.
  22. Brauer CA, Coca-Perraillon M, Cutler DM, Rosen AB. Incidence and mortality of hip fractures in the United States. JAMA. 2009 Oct 14;302(14):1573-9.
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