Femoral Neck Fractures Presentation and Treatment

Femoral neck fractures or fractures of neck of femur are fractures of proximal femur in the region between head of femur and intertrochanteric line [called neck of femur]

These injuries are common in two distinct populations – young and elderly

In young patients, femoral neck fractures are also caused by high-energy trauma whereas in elderly population, the fractures occur with insufficient trauma.

Stress fractures of the femoral neck are uncommon and occur in active individuals with unaccustomed strenuous activity or changes in activity, such as runners or endurance athletes, and elderly individuals with osteoporosis.

Long-distance runners who suddenly change or add activities have a higher prevalence of femoral neck stress fractures.

Insufficiency fractures are more common in females secondary to osteoporosis.

One of the unique features of femoral neck fractures is limited healing potential because femoral femoral neck is intracapsular, bathes in synovial fluid and lacks lacks periosteal layer. All these fractures contribute to poor healing.

Causes of Femoral Neck Fractures

Traumatic Fractures

Seen with significant trauma, usually seen in young people

Osteoporotic Fractures

Seen in elderly, osteoporosis a contributory factor

Stress fractures

Usually seen in athletes

• Sudden increase in the quantity or intensity of training
• Introduction of a new activity
• Contributory Factors
  • Low bone density
  • Dietary deficiencies
  • Biomechanical abnormalities
  • Menstrual irregularities.

• Exercise-induced endocrine abnormalities
• Gluteus medius fatigue – Decreases shock absorbing capacity resulting in higher stresses on femoral neck

• Malalignment syndrome- Femoral neck anteversion, genu valgum, increased Q-angle, tibia vara, and compensatory foot pronation
  • an unequal distribution of stress and tension across the hip joint.

Relevant  Anatomy and Biomechanics

Read more about anatomy of hip joint and proximal femur

Femoral neck is part of proximal femur and is a participant in formation of hip joint. It functions to connect articular head of femur to shaft of femur.

The synovial membrane incorporates the entire femoral head and the anterior neck, but only the proximal half of the posterior neck. The shape and size of the femoral neck vary widely.

Normal neck shaft-angle 130 +/- 7 degrees and normal anteversion 10 +/- 7 degrees.

Read more about anteversion and retroversion

The blood supply to the proximal end of the femur is divided into 3 major groups. The first is the extracapsular arterial ring located at the base of the femoral neck. The second is the ascending cervical branches of the arterial ring on the surface of the femoral neck. The third is the arteries of the ligamentum teres.

Medial femoral circumflex artery is major contributor (lateral epiphyseal artery). Contribution to anterior and inferior head comes from lateral femoral circumflex arter along with some  contribution from inferior gluteal artery

Artery of ligamentum teres provides small and insignificant supply.

Displacement of femoral neck fracture disrupts the blood supply and may put femoral head at risk of osteonecrosis.

Osteonecrosis of the femoral head is most dreaded complication of femoral neck fractures and is reported to occur in 9% to 35% of displaced femoral neck fractures.

The degree of fracture displacement determines the severity of damage to the major blood supply, the lateral epiphyseal artery system.

Intracapsular hematoma may elevate the capsular pressure which has an adverse effect on femora head blood flow and may induce cellular death.

Anatomical reduction of femoral neck fractures has been shown to lower the risk of femoral head osteonecrosis. Second, stable fracture fixation allows revascularization to proceed in an optimal mechanical environment.

During walking or running, the load on the femoral neck can exceed 3-5 times the body weight when an individual is walking or running. Gluteus medius and minor muscles counterbalance the force of gravity on hip joint.

These forces on the femoral head are transmitted through the femoral neck to the shaft, resulting in significant amount of stress on the femoral neck as a result of compression and bending.

The inferior aspect of the femoral neck faces these forces of compression leaving superior aspect with minimal effect.

However, on bending forward, stress is induced on the superior aspect of the femoral head.

Classification of Femoral Neck Fractures

Garden Classification

(based on AP radiographs and does not consider lateral or sagittal plane alignment)

Type I

Incomplete, ie. valgus impacted

Type II

Complete fracture but nondisplaced

Type III

Complete, partially displaced

Type IV

Complete, fully displaced

It was found that  clinically differentiating the 4 grades of fractures is difficult. Hence, classifying femoral neck fractures as nondisplaced (Garden grades I or II) or displaced (Garden grades III or IV) is more accurate..

Simplified Garden Classification

Nondisplaced

Includes Garden I and II

Displaced

Includes Garden III and IV

Pauwels Classification

(based on vertical orientation of fracture line)

Type I

< 30 deg from horizontal

Type II

30 to 50 deg from horizontal

Type III

> 50 deg from horizontal (most unstable with highest risk of nonunion and avascular necrosis)

Devas Classification of Stress Fractures

 Tension type  stress fracture

• A transverse fracture directed perpendicular to the line of force transmitted in the femoral neck
• Originates at the superior surface of the femoral neck
• Has risk of displacement

Compression type of femoral neck stress fracture,

• Located at the inferior margin of the femoral neck
  • Visualized as haze of internal callus
  • Eventually, a small fracture line appears in this area, and gradually scleroses.
• No cortical discontinuity.
• Mechanically stable
• Younger patients

Fullerton and Snowdy added displaced type as third group of  femoral neck stress fracture classification

Clinical Presentation of Femoral Neck Fractures

Impacted and stress fractures  may present as slight pain in the groin or pain referred along the medial side of the thigh and knee. Displaced fractures present as pain in the entire hip region.

Displaced fractures would also show inability to bear weight on the affected extremity and deformity of the lower limb.

On examination, impacted and stress fractures would show no obvious clinical deformity. Minor  discomfort with active or passive hip range of motion may be noted. Muscle spasms occurs  at extremes of motion.

Percussion over greater trochanter may reveal pain.

Displaced fractures have leg in external rotation and abduction, with shortening

For evaluation of stress fractures, a careful history is obtained to ascertain the cause.

If the person is athlete , there may be a recent  recent change in training or equipment. It could be increase in mileage or  intensity, changing the  terrain, or running shoes.

Features common to all stress fractures include the following:

• Participation in repetitive cyclic activity
• Insidious onset of pain
• Recent change in activity or equipment
• No history of significant trauma
• Pain with weight bearing
• Relief of pain with rest
• Menstrual irregularities
• Predisposing osteopenia

Hop Test

This test involves the patient hopping on the affected leg to reproduce symptoms. Other maneuvers that can place a stress on the femur also may reproduce pain. It is found to be positive in approximately 70% of patients with stress fractures of the femoral neck.

Lab Studies

Not required for diagnosis of traumatic fractures. May be required in case of evaluation of causes of stress fractures.

Imaging Studies

X-rays

Following are recommended x-ray views

• AP pelvis
• Cross-table lateral, and full length femur film
• Traction-internal rotation AP hip

X-rays help to determine the site and extent of the fracture. However, a plain radiograph may appear normal in a patient with a femoral neck stress fracture.

If a femoral neck fracture is suggested, an internal rotation view of the hip may be done  to identify nondisplaced or impacted fractures.

CT

CT is helpful in determining displacement and degree of comminution in some patients. It can also define bone lesions better than MRI in case of pathological fractures

MRI

MRI is helpful to rule out occult fracture  but cannot be relied upon for assessing viability of femoral head after fracture.

Bone scan

It is also helpful to rule out occult fracture and when a stress fracture, tumor, or infection is suggested.

Treatment of Femoral Neck Fractures

Treatment Approach

Undisplaced Fractures/Stress Fractures

If the stress fractures are identified early and fracture is uncomplicated fractures rest and reversal any training errors may help to prevent progression of the fracture.

Compression stress fractures are more stable can be treated nonoperatively.

These undisplaced fractures are treated with bed rest and/or the use of crutches. The treatment is continued  until passive hip movement is pain-free and there is an evidence of callus formation.

Close radiographic monitoring is required as the risk of displacement of the fracture is high.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.

Immediate open reduction and internal fixation is indicated if the fracture starts widening.

Tension fractures are potentially unstable and may require operative stabilization.

In elderly patients,  observation alone may be considered in some patients who are non-ambulators, have minimal pain, and who are at high risk for surgical intervention

Displaced Fractures

The treatment of a displaced fracture is based on the person’s age and activity level.

In the elderly population, cognitive function, walking ability, and independence in activities of daily living should be considered to arrive at optimal method of surgical repair.

A displaced fracture in a young patient is an orthopedic emergency, and early open reduction and internal fixation is necessary. In elderly patients, treatment options include open reduction and internal fixation or prosthetic replacement.

Surgical Procedures

Closed/Open Reduction and Internal Fixation

Closed or open reduction and internal fixation is indicated in displaced fractures in young or physiologically young patients [for most patients <65 years of age]. It is the most common surgical procedure performed in fracture of neck of femur.

Following options are available in fracture fixation.

Cannulated screw fixation

• Garden I and II fracture patterns in the physiologically elderly
• Displaced transcervical fx in young patient

• A surgical emergency
• Anatomic reduction is warranted

Sliding hip screw or cephalomedullary nail

These are biomechanically superior to cannulated screws and is  indicated in

• Basicervical fracture
• Vertical fracture pattern in a young patient
• When associated with femoral shaft fracture
• Placement of additional cannulated screw above sliding hip screw prevents rotation

Hip Replacement

This is done in  elderly patients.

Hemiarthroplasty [ Replacement of femoral part of hip-joint only] – in hip with without arthritis.

Total hip arthroplasty is considered in patients with preexisting hip osteoarthritis. It provides better pain relief and better functional outcome than hemiarthroplasty in arthritis hips.

Complications of Femoral Neck Fractures

Osteonecrosis

Incidence of osteonecrosis is 10-45%. The risk increases with initial displacement.

In young patients > 50% involvement is treated with free vascularized fibular graft or total hip arthroplasty.

In older patients hemiarthroplasty or total hip arthroplasty is considered.

Nonunion

Nonunion has an incidence of 5 to 30%. Displaced fractures have increased incidence in displaced fractures. There is no correlation between age, gender, and rate of nonunion

Varus malreduction most closely correlates with failure of fixation after reduction and cannulated screw fixation.

Treatment options in non union are is by following options

• Valgus intertrochanteric osteotomy
• free vascularized fibula graft (FVFG)
• Arthroplasty
• revision open reduction and internal fixation

Dislocation

Higher rate of dislocation with total hip arthroplasy than than hemiarthroplasty

Special Situations

Parkinson’s Disease

Patients with parkinson’s disease who sustain a femoral neck fracture present a special challenge, as morbidity and mortality rates are much higher.

To decide on an appropriate treatment plan, it is essential to consider the status of the disease and view cases individually.

In cases of nondisplaced or impacted fracture, a patient of any age or disease severity should be treated with multiple-screw fixation and early mobilization.

Young and active with displaced femoral neck fractures with well controlled disease should be treated by anatomic reduction and internal fixation.

Older patients with displaced fractures or younger patients with poorly controlled disease are treated by cemented prosthetic replacement.

Paget’s  Disease

Delayed union and nonunion are common sequelae of fractures in Paget’s disease.

The treatment of choice for displaced femoral neck fractures in Paget’s disease is primary prosthetic replacement.

• If acetabular involvement is minimal and minimal preinjury symptoms, then a hemirarthroplasty should be performed.
• If there are significant preinjury symptoms and/or extensive acetabular involvement with secondary degenerative change, total hip replacement is indicated.

Spastic Hemiplegia

Treatment of these patients may be problematic because of osteopenia, spasticity, and/or contracture.

• Nondisplaced fractures in ambulatory patients with minimal spasticity – internal fixation.
• Displaced fractures in ambulatory patients with minimal spasticity – appropriate treatment for age and fracture.
• Severe spasticity and contracture – primary prosthetic replacement combined with muscle and tendon releases to correct the contracture, irrespective of displacement.

Chronic Renal Failure

Because of high rate of non union, primary prosthetic replacement appears to be the treatment of choice for femoral neck fractures in patients with chronic renal failure.