Femoral Neck Stress Fracture 

Updated: May 31, 2017
Author: Scott D Flinn, MD; Chief Editor: Sherwin SW Ho, MD 

Overview

Background

Stress fractures are a problem in various populations including runners and military trainees.[1, 2, 3] These fractures can occur with as little as 2-3 weeks of training, be very mild, causing only minimal changes to the bone which eventually heals, or they may progress to a complete fracture that requires surgical fixation. Although rare, poor outcomes may occur in the form of nonunions or avascular necrosis. Certain stress fractures have a higher risk of poor outcome, including anterior tibial and femoral neck stress fractures (FNSFs).

(See also the articles Femoral Head Avascular Necrosis [in the Sports Medicine section], Avascular Necrosis, Femoral Head and Stress Fracture [in the Radiology section], and Stress Fracture [in the Physical Medicine and Rehabilitation section], as well as Risk Factors for Bone tress Injuries: A Follow-up Study of 102,515 Person-Years and Total Hip Arthroplasty in the Older Population on Medscape.)

FNSFs (see image below) are some of the most difficult injuries to diagnose. The pain associated with such an injury may be poorly localized in the hip and may be referred to the thigh or back. Physical examination findings are not very specific for this injury, and diagnostic radiographs in the form of x-ray films, bone scans, and/or magnetic resonance images (MRIs) are often necessary.[4] Failure to diagnose FSNFs may lead to catastrophic consequences, including avascular necrosis of the femoral head and the need for a hip replacement in otherwise healthy young individuals.[5, 6, 7] A high index of suspicion in the appropriate risk populations is the key to diagnosing and treating FNSFs.

Radiograph showing a tension-side, completed femor Radiograph showing a tension-side, completed femoral neck stress fracture.

(See also the article Femoral Neck Stress and Insufficiency Fractures.)

For patient education resources, see the Foot, Ankle, Knee, and Hip Center; Breaks, Fractures, and Dislocations Center; and Sports Injury Center, as well as Broken Leg and Total Hip Replacement.

Epidemiology

Frequency

United States

Stress fractures may develop in up to 15% of runners and military trainees.[3] Of those patients who develop stress fractures, about 5-10% of the fractures are in the femoral neck.[8] Stress fractures on the compression side (the inferior aspect) of the femoral neck are more common than stress fractures on the tension side (the superior aspect).

Functional Anatomy

The femoral neck lies between the femoral head and femoral shaft, demarcated by the greater and lesser trochanters. Weight-bearing forces from the trunk cause a compressive force on the inferior aspect of the femoral neck, whereas the superior aspect is subject to tensile forces.[6, 9] The blood supply to the femoral head runs through the femoral neck; thus, an FNSF may disrupt the blood supply to the femoral head and cause avascular necrosis of the femoral head.[6]

Sport-Specific Biomechanics

The load of the runner's body weight is transmitted down the lower extremities through the bones and may exceed 3-5 times the body weight in the femoral neck during running. Muscles help to absorb forces and distribute load, especially the gluteus medius. The weight of the trunk and upper extremities applies compressive forces to the inferior aspect of the femoral neck. Conversely, tensile forces act upon the superior aspect of the femoral neck. These forces become important in the prognosis and management of the stress fracture. A sudden reduction in weight and lower muscle mass combined with daily training was associated with an increased risk of FNSF in US Naval Academy plebes.[3]

 

Presentation

History

Runners and military trainees develop stress fractures as the duration, frequency, and intensity of weight-bearing activities is increased. Furthermore, changes in running surfaces, such as from a flat surface to hills, or carrying a pack may increase the risk of stress fractures.

The patient reports a gradually worsening deep, achy pain in the hip, groin, or thigh.

Usually, pain initially occurs after an activity. As the stress of training continues, pain occurs during training and becomes more intense.

Unless the form of the activity is modified, the pain gradually worsens over a few weeks to the point where the patient is unable to walk without pain.

Continued activity will probably result in completion of the stress fracture.

Physical

Physical examination reveals the patient to have an antalgic gait.

Unlike many other stress fractures, it is not possible to palpate the femoral neck and determine the presence of the usual bony tenderness of a stress fracture. However, hip palpation may suggest another diagnosis, such as a hip flexor strain, if pain is present at the anterior inferior iliac spine and upon hip flexion. It is difficult to determine if anterior hip pain is due to a hip flexor strain or an FNSF by examination alone. Other possible diagnoses include greater trochanteric bursitis, adductor strain, or a pubic ramus stress fracture. (See also the articles Trochanteric Bursitis [in the Sports Medicine section], Adductor Strain [in the Physical Rehabilitation and Medicine section], and Pelvic Fractures [in the Orthopedic Surgery section].)

Pain at the extremes of passive range of motion (ROM), especially external and internal rotation, is the most sensitive sign for stress fractures.

Pain that is associated with log rolling, axially loading a supine patient (heel tap), and with single-leg standing or hopping also suggests a stress fracture. (Note: Performing a single-leg hopping test in a patient with a potential FNSF is risky and may cause completion of the stress fracture; this practice is not advised.)

Causes

Improper training is the most obvious cause for a stress fracture. Increasing the duration, frequency, and/or intensity of training too quickly does not allow for proper bone and supporting muscle adaptation, resulting in microscopic damage to the bone, which cannot be healed quickly.

In the military population, trainees who have initially lower levels of fitness and higher body mass indexes are at an increased risk of stress fractures.[1] A history of a previous stress fracture is also a risk factor for a recurrence. In addition, coxa vara has been associated with an increased risk of FNSF.[10] Finally, a study on male US Marine Corps recruits showed a higher risk of stress fracture with low body weight and small femoral diaphysis.[11]

Other hypothesized risk factors for FNSF include improper footwear, leg-length discrepancies, and a change of the running surface.

Females with the female athlete triad (ie, disordered eating, menstrual dysfunction, premature osteoporosis) are also at increased risk for stress fractures. (See also the article Female Athlete Triad.)

Young women who perform weightbearing exercise regularly can increase the bone density of their femoral neck.[12]

Plebes undergoing training at the US Naval Academy who had significant weight loss and smaller muscle mass were associated with a much higher incidence of stress fracture than their fitness-matched cohorts.[3]

A study by Goldin et al suggested that femoral neck stress injury patients have a higher incidence of bony abnormalities associated with pincer impingement, including coxa profunda and acetabular retroversion, however, further studies are needed to evaluate this relationship.[13]

 

DDx

 

Workup

Laboratory Studies

Consider laboratory studies with a CBC count and erythrocyte sedimentation rate (ESR) if infection, inflammatory arthropathy, or a tumor is suspected.

Imaging Studies

X-ray films (see images below)

Radiograph showing a tension-side, completed femor Radiograph showing a tension-side, completed femoral neck stress fracture.
Radiograph showing sclerosis on the compression si Radiograph showing sclerosis on the compression side of the femoral neck.

Obtain anteroposterior and frog-leg views.

Obtain appropriate radiographs if femoral shaft or pubic ramus fractures are suspected. (See also the article Femur Injuries and Fractures.)

If the initial radiographs are negative (and they often are), and the suspicion for FNSF is high based on the patient history and physical examination, obtain a bone scan or MRI.[4] Instruct the patient to remain non-weight bearing on crutches until the study is obtained.

If the patient's symptoms are mild, or bone scanning or MRI is unavailable, the patient should be on crutches, non-weight bearing or touchdown weight bearing, until the bone scan/MRI is obtained or repeat films in 2 weeks are negative.

See image below of a bone scan depicting FNSF.

Radiographs are often initially negative for stres Radiographs are often initially negative for stress fractures, including femoral neck stress fractures. Repeating x-ray films in 2 weeks may show the changes of a stress fracture, but approximately 20% of cases do not. Bone scanning or magnetic resonance imaging may be necessary to rule out a stress fracture. In the x-ray film for this patient, no changes were seen, but a bone scan showed an obvious compression stress fracture of the right femoral neck.

MRI

MRI yields more diagnostic information than bone scanning and is especially more useful in difficult cases.[4, 14]

Other Tests

Other tests, such as hip joint aspiration for a septic joint, are only indicated if the clinician is considering alternative diagnoses.

 

Treatment

Acute Phase

Rehabilitation Program

Physical Therapy

Tension-side FNSF should be non-weightbearing and receive immediate referral to an orthopedic surgeon. Compression-side fractures may be treated conservatively. Compression-side fractures should be referred as appropriate for expert care if not familiar with their treatment.

Follow the acute treatment principles of protection, rest, ice, compression, elevation, medication, and modalities (PRICEMM). This treatment regimen is most appropriate for compression (as opposed to tension) fractures. Patient compliance is important.

  • Protection – Crutches with non–weight-bearing ambulation until complete relief of pain at rest is achieved

  • Rest – Non-weight bearing if there is pain at rest; may do alternative exercises to maintain cardiovascular conditioning (eg, swim, upper-extremity Exercycle [Exercycle Company, Franklin, Mass])

  • Ice – To assist with pain reduction

  • Elevation – Usually difficult

  • Medication – Consider low-dose nonsteroidal anti-inflammatory drugs (NSAIDs) for pain relief or narcotics if the patient has severe pain. NSAIDs should be given for as short a time as possible as they may interfere with bone healing.[15, 16]

  • Modalities – Not much help acutely

Medical Issues/Complications

Nondisplaced compression-side FNSFs do well with conservative treatment, ie, non-weightbearing on crutches, with a gradual progression to touchdown weightbearing, partial weight bearing, then to no crutches in 4-6 weeks depending on the clinical response. These patients do not appear to be at increased long-term risk for avascular necrosis of the femoral head or osteoarthritis.[17]

Nondisplaced tension-side fractures are usually treated with surgical pinning. Rarely, conservative treatment such as for compression-side fractures is attempted for small, nondisplaced tension-side FNSFs. Displaced fractures are treated surgically.

Surgical Intervention

Surgical intervention is dependent on the type of fracture. Compression-side fractures can be treated with conservative therapy. Nondisplaced tension-side FNSFs are usually treated with prophylactic surgical fixation. Rarely, a trial of conservative therapy in compliant patients may be attempted if the tension-side fracture is small and not displaced. Urgently refer the patient for orthopedic evaluation for surgical fixation in cases of displaced fractures.

Consultations

Consult an orthopedic specialist if the patient's rehabilitation for an FNSF is not progressing adequately, if it is displaced, or for any other concerns.

Other Treatment

Review the patient's diet; ensure adequate calcium and vitamin D intake, and supplement as needed. Consider oral contraceptives for amenorrheic women; such agents may aid in the recovery of bone mass in these women. Athletes with eating disorders may need psychologic and nutritional support.

Recovery Phase

Rehabilitation Program

Physical Therapy

As the patient’s pain decreases, gradually increase activity from non-weight bearing to touchdown weight bearing, then to partial weight bearing, and eventually, discontinuation of the crutches. This process usually takes 4-6 weeks. Coordinate the patient's rehabilitation with the orthopedic specialists for those individuals who have hips with surgical pinning. After the patient is able to walk 1.5 miles without pain (usually in 8-12 wk, but sometimes longer), begin a gradual return to a running program. Usually, it takes approximately 2.5 months to be able to run 3 miles pain free. If pain returns during the rehabilitation period, decrease the patient's activity until walking is pain free again.

Non–weight-bearing training can also play a role in the patient's rehabilitation. Activities such as running in water with an appropriate floatation vest can be helpful. Upper-extremity resistance exercises and aerobic training can also be used.

Medical Issues/Complications

A very mild pain may return briefly when the patient first attempts to run. If the pain is more than a very mild intensity, the stress fracture may not have healed completely yet and needs additional rest. If the patient's pain is severe, obtain another x-ray to check for displacement. Avascular necrosis, nonunion, malunion, and eventual hip replacement may result from complications of an FNSF that is not diagnosed in time or that is rehabilitated too quickly.

Surgical Intervention

If the patient has a nondisplaced tension-side fracture and the pain persists for longer than 2 weeks—despite true compliance with non-weightbearing status—consider surgical fixation if the procedure has not already been performed.

Consultations

Consult an orthopedic specialist if the patient's rehabilitation for an FSNF is not progressing adequately.

Other Treatment (Injection, manipulation, etc.)

Ensure the patient has an adequate calcium and vitamin D intake. If an eating disorder is present, monitor the patient's treatment and help the patient recover proper dietary and weight-management habits.

Maintenance Phase

Rehabilitation Program

Physical Therapy

Monitor the patient's activity to ensure that the same training errors that initially resulted in the stress fracture are not committed again. Gradual increases in mileage (≤ 10%/wk) are generally accepted as safe and effective. Likewise, the intensity of the patient's workouts should increase gradually, not dramatically.

Medical Issues/Complications

If the same type of pain reappears despite therapy, the patient should return to the clinician to check for a recurrent stress fracture.

Surgical Intervention

If the femoral neck was surgically fixed, consult the orthopedic specialist regarding when (if ever) the pins should be removed.

Consultations

Obtain an orthopedic consultation if the patient's recovery is not progressing adequately.

Other Treatment

The patient should continue calcium supplementation, if necessary. Monitor for recurrence of an eating disorder, if appropriate.

 

Medication

Medication Summary

The goals of pharmacotherapy are to reduce morbidity and to prevent complications in patients with FNSFs.

Mineral supplements

Class Summary

Calcium supplementation may be necessary for patients with FNSFs. The average daily recommendations for children aged 9-18 years is 1300 mg of calcium daily. Individuals aged 19-50 years and postmenopausal women should have a daily calcium intake of 1000 mg of calcium. Middle-aged women and males 50 years and older should receive 1200 mg of calcium daily. Vitamin D supplementation may also be necessary.

Calcium carbonate (Os-Cal)

Used for the supplementation of calcium. Give the amount that is needed to supplement an individual's diet to reach the recommended daily amounts.

Calcium citrate (Citracal)

Moderates nerve and muscle performance by regulating the action potential excitation threshold. Give the amount that is needed to supplement an individual's diet to reach the recommended daily amounts.

Nonsteroidal anti-inflammatory drugs

Class Summary

NSAIDs have analgesic, anti-inflammatory, and antipyretic activities. The mechanism of action of these agents is not known, but they may inhibit cyclooxygenase activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions. Many NSAIDs are currently on the market. There is no evidence to support that one agent is more efficacious than another; however, individual response may differ.

The routine use of NSAIDs for treating stress fractures has been called into question because these drugs have been shown to slow bone formation and may mask the pain that serves as a guide for the timing of advancing rehabilitation.[15, 16] Therefore, administer NSAIDs sparingly for initial pain, if at all. Furthermore, with the other complications of NSAIDs (eg, gastrointestinal [GI] bleeding) and the known difficulties with COX-2 inhibitors, caution is advised.

Ibuprofen (Motrin, Ibuprin)

DOC for patients with initial mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis. May slow bone healing, so use sparingly.

Naproxen (Aleve, Naprelan, Naprosyn, Anaprox)

For relief of mild to moderate pain; inhibits inflammatory reactions and pain by decreasing the activity of cyclooxygenase, which results in a decrease of prostaglandin synthesis. May slow bone healing, so use sparingly.

Ketoprofen (Actron, Orudis, Oruvail)

For relief of mild to moderate pain and inflammation.

Small dosages are initially indicated in small and elderly patients and in those with renal or liver disease. Doses over 75 mg do not increase therapeutic effects. Administer high doses with caution, and closely observe patient for response. May slow bone healing, so use sparingly.

 

Follow-up

Return to Play

Once the athlete has completed the walk/run rehabilitation program and is able to run 3 miles without pain, gradually increase the mileage (no more than 10% per wk) until the goal level is obtained. Gradual sport-specific drills and higher-intensity training should be accomplished over a few weeks.

Complications

Nondisplaced compression-side FNSF appears to have no increased long-term risk for avascular necrosis of the femoral head or osteoarthritis for these patients.[17]

Compression-side nondisplaced FNSFs may recur and become displaced, especially if the patient is returned to activity too quickly. Displaced tension-side FNSFs have complications that include avascular necrosis of the femoral head and need for total hip arthroplasty (THA).

Prevention

Prevention of FNSFs includes gradually increasing the intensity and duration of training, halting/decreasing training upon return of symptoms, and reevaluating the patient for stress fracture recurrence; providing adequate calcium intake, and further treatment of an eating disorder if appropriate.

Prognosis

FNSFs are often difficult to diagnose. The patient's history of increasing hip pain while running and physical examination findings of pain upon internal and/or external rotation of the hip or pain upon single-leg standing should arouse clinical suspicion of an FNSF. (Note: Single-leg hopping on the affected leg may complete the fracture and should be highly discouraged.)

The patient should be restricted to crutches, non-weight bearing or touchdown weight bearing, if it causes no pain. Perform further investigation, including radiography, bone scanning, and/or MRI. A missed FSNF that was originally diagnosed as bursitis or tendonitis, with the patient allowed to return to sports, only to have the patient snap the femoral neck and eventually require an artificial hip, is obviously not the desired outcome. A completed displaced FNSF has about a 25% chance of having a poor outcome even with surgical fixation; thus, diagnosing these injuries before completion of the fracture is essential.