Orthopaedic Surgery - Stress Fracture

Basics

A stress fracture develops when:

Repetitive mechanical loading exceeds the ability of bone to remodel and repair itself.

With continued loading, microscopic damage accumulates until the bone develops a:

Structural fracture.

Fatigue Fracture

A fatigue-type stress fracture occurs when:

Abnormally repetitive or suddenly increased forces

are applied to otherwise:

Normal bone.

A classic example is a:

Metatarsal stress fracture

in a military recruit who suddenly begins prolonged marching without adequate:

Conditioning.

Insufficiency Fracture

An insufficiency fracture is related but occurs when:

Normal physiologic loads

are applied to:

Weak or osteopenic bone.

An example is a:

Femoral neck insufficiency fracture

in an older patient with:

Low bone density.

Common Sites

Stress fractures occur most frequently in:

Weight-bearing bones of the lower extremity.

Common locations include:

Metatarsals

Calcaneus

Tibia

Fibula

and

Femoral neck.

Synonyms

Other terms include:

Fatigue fracture

and

March fracture.

MRI/Radiographic Grading

Stress injuries may be classified according to:

Radiographic and MRI findings.

Grade I

Grade I injury demonstrates:

Normal radiographs

with abnormal signal on:

STIR MRI sequences.

This represents an early:

Bone stress reaction.

Grade II

Grade II injury demonstrates:

Normal radiographs

with abnormalities on:

STIR

and

T2-weighted MRI.

Grade III

Grade III injury may show:

Periosteal reaction on radiographs

with abnormalities on:

T1

T2

and

STIR MRI

but without a definite:

Cortical fracture line.

Grade IV

Grade IV injury demonstrates a definite:

Fracture line

on radiographs or MRI.

MRI abnormalities are seen on:

T1

and

T2-weighted sequences.

General Prevention

Prevention focuses on avoiding sudden increases in:

Training load.

Training Progression

Athletes should increase:

Running distance

Intensity

and

Impact loading

gradually.

Abrupt changes in training are a major risk factor for:

Bone stress injury.

Running Mileage

A commonly used training principle is to avoid increasing weekly running mileage by more than approximately:

10% per week.

This is not an absolute biological threshold, but it provides a practical framework for gradual:

Load progression.

Pain Awareness

Athletes should reduce or stop training when they develop:

New focal pain during activity.

Continuing through pain can convert an early stress reaction into a:

Complete fracture.

Bone Health

Prevention also requires optimization of:

Energy availability

Calcium intake

Vitamin D status

and overall:

Bone health.

Epidemiology

Stress fractures can occur at:

Any age.

Younger Patients

Patients younger than approximately:

60 years

usually develop fatigue-type fractures after:

Repeated or sustained physical activity.

Older Patients

Older adults are more likely to develop:

Insufficiency fractures

when normal activity is applied to:

Osteopenic or otherwise weakened bone.

Sex

Stress and insufficiency fractures occur more commonly in:

Females

than in males.

Athletic Populations

They are particularly common in:

Runners

Jumping athletes

Military recruits

and athletes exposed to repetitive:

Impact loading.

Military Recruits

Historical studies have reported stress fractures in approximately:

5% of military recruits.

Elite Athletes

Rates vary according to sport and training exposure.

Historical data from elite tennis players have reported rates around:

12%.

Femoral Stress Fractures

Femoral stress fractures have been reported at approximately:

20 per 100,000 person-years.

About half involve the:

Femoral neck.

Risk Factors

Important risk factors include:

Female sex

Low bone mineral density

Smoking

Sudden increase in training

High running mileage

Low aerobic fitness

Excessive alcohol intake

Low vitamin D

Poor recovery time

and

Abnormal biomechanics.

Relative Energy Deficiency

A major risk factor is:

Low energy availability

with or without:

Disordered eating.

This may be associated with:

Menstrual dysfunction

and

Reduced bone mineral density.

Historically, this constellation was called the:

Female athlete triad.

A broader modern concept is:

Relative Energy Deficiency in Sport, or RED-S.

Female Athlete Triad

The classic triad consists of:

Low energy availability

Menstrual dysfunction

and

Low bone density.

Any component can increase the risk of:

Stress fracture.

Smoking

Smoking adversely affects:

Bone health

and may increase susceptibility to:

Stress injury.

Alcohol

Higher alcohol consumption, historically more than approximately:

10 drinks per week

has been associated with increased:

Stress fracture risk.

Low Vitamin D

Low serum:

25-hydroxyvitamin D

is associated with impaired:

Bone mineralization

and increased risk of:

Bone stress injury.

Running Volume

Recreational running above approximately:

25 miles per week

has historically been associated with increased risk, particularly when combined with:

Rapid progression

or inadequate recovery.

Skeletal Alignment

Biomechanical factors may increase local stress.

Examples include:

Pes planus

Pes cavus

and excessive:

Hip external rotation.

Muscle Fatigue

Muscles normally absorb part of the:

Impact load.

As they fatigue, less shock is absorbed and more force is transmitted directly to:

Bone.

This is particularly relevant in:

Long-distance running.

Etiology

The fundamental mechanism is:

Repeated loading that exceeds bone adaptation.

Younger Individuals

In younger people, the typical cause is a:

Sudden increase in strenuous activity

applied to otherwise normal:

Bone.

Older Individuals

In older patients, fractures may occur under relatively normal loads because of:

Osteoporosis

Osteopenia

or other:

Metabolic bone disease.

Associated Conditions

Stress fractures may be associated with:

Osteopenia

Osteoporosis

Metabolic bone disease

Female athlete triad

and

RED-S.

Diagnosis

Diagnosis depends on:

History

Physical examination

and appropriate:

Imaging.

Early recognition is important to prevent progression to:

Complete fracture.

Signs and Symptoms

The typical presentation begins with:

Gradual activity-related pain.

Early Symptoms

Patients often describe approximately:

2–3 weeks

of a vague:

Dull ache

during:

Exercise or impact loading.

Progression

As the injury progresses, pain becomes:

Sharper

More localized

and begins:

Earlier during activity.

Advanced Injury

With increasing severity, pain may persist after exercise and eventually occur:

At rest.

Rest pain suggests a more advanced:

Bone stress injury.

Complete Fracture

If a stress injury progresses to a complete fracture, pain may become:

Sudden

Severe

and associated with major:

Functional limitation.

Physical Examination

The examination should identify:

Focal bone tenderness

and assess the patient’s ability to:

Bear weight.

Gait

An:

Antalgic gait

may be present.

Point Tenderness

One of the most characteristic findings is:

Localized tenderness directly over the involved bone.

Diffuse tenderness is less typical of a discrete:

Stress fracture.

Swelling

There may be:

Soft-tissue swelling

or localized thickening over the:

Affected site.

Hop or Impact Pain

Pain reproduced with:

Impact loading

may support the diagnosis but should be used cautiously when a high-risk fracture is suspected.

Femoral Neck Stress Injury

Femoral neck lesions may produce:

Groin pain

or

Anterior thigh pain.

Pain may be reproduced with:

Hip rotation

or resisted:

Straight-leg raise.

Stinchfield Test

Pain with resisted active straight-leg raise, sometimes called a:

Stinchfield sign

may occur with:

Femoral neck or intra-articular hip pathology.

It is not specific to stress fracture.

Laboratory Tests

Routine laboratory testing is not necessary for every stress fracture.

Metabolic Bone Evaluation

Laboratory workup should be considered in patients with:

Recurrent stress fractures

Older age

Low bone density

RED-S

Menstrual abnormalities

or suspected:

Metabolic bone disease.

Possible Laboratory Studies

Depending on the clinical setting, testing may include:

25-hydroxyvitamin D

Calcium

Phosphate

Parathyroid hormone

Renal function

and selected endocrine:

Studies.

Imaging

Plain Radiographs

Initial imaging usually includes:

AP and lateral radiographs.

Early Radiographs

Radiographs are frequently:

Normal during the first 1–2 weeks

after symptoms begin.

A normal early radiograph therefore does not exclude:

Stress fracture.

Later Radiographic Findings

With healing or progression, radiographs may show:

Periosteal reaction

Sclerosis

Cortical thickening

or a visible:

Fracture line.

Bone Scan

Bone scintigraphy is:

Highly sensitive

for increased bone turnover.

Bone-Scan Limitations

It is less specific than:

MRI

because many disorders produce increased:

Tracer uptake.

Delayed Positivity in Older Adults

In elderly patients with insufficiency fractures, scintigraphic abnormalities may occasionally be delayed for:

48–72 hours.

MRI

MRI is the preferred advanced imaging technique for most suspected:

Stress injuries.

MRI Advantages

MRI is:

Highly sensitive

and generally more:

Specific

than bone scintigraphy.

It can detect:

Bone marrow edema

before a fracture line becomes visible.

MRI Prognostic Value

MRI can classify severity and help estimate:

Time to return to activity.

Soft-Tissue Evaluation

MRI can also identify alternative causes of pain such as:

Tendon injury

Muscle injury

or

Joint pathology.

CT

CT may be useful for selected lesions when detailed evaluation of:

Cortical bone

or fracture healing is required.

It is particularly helpful in some:

Navicular

or

Anterior tibial cortex lesions.

Differential Diagnosis

Important alternatives include:

Acute fracture

Infection

Tumor

Soft-tissue injury

Exertional compartment syndrome

and, for tibial pain,

Medial tibial stress syndrome.

Medial Tibial Stress Syndrome

Shin splints generally produce:

Diffuse posteromedial tibial tenderness

rather than the focal tenderness characteristic of a:

Stress fracture.

Treatment

Treatment depends primarily on:

Fracture location

Risk category

Symptoms

and evidence of:

Fracture progression.

General Measures

The basic treatment principle is:

Reduce loading below the threshold that produces pain.

Walking Pain

If walking is painful, patients should use:

Crutches

or another method of:

Protected weight bearing.

Rest Pain

If pain occurs at:

Rest

or with minor motion, more complete protection may be needed using:

A boot

Splint

or

Cast.

Low-Risk Stress Fractures

Most low-risk fractures are treated with:

Activity modification

and progressive:

Protected loading.

Examples commonly include many:

Metatarsal shaft

Fibular

and

Posteromedial tibial stress fractures.

High-Risk Stress Fractures

High-risk injuries require more aggressive treatment because they have an increased risk of:

Displacement

Delayed union

Nonunion

or catastrophic:

Complications.

Activity Progression

Once symptoms have resolved, activity should be resumed:

Gradually.

Low-Impact Training

The patient may first begin:

Cycling

Swimming

Pool running

or other:

Low-impact conditioning.

Return to Running

Running should resume only when the patient can perform normal daily activities and impact testing without:

Pain.

Mileage should then increase:

Slowly and progressively.

Physical Therapy

Rehabilitation should identify the factor that caused the:

Stress injury.

Training Errors

Common issues include:

Sudden mileage increases

Excessive intensity

Insufficient rest

and repeated training on:

Hard surfaces.

Biomechanical Assessment

Therapy may evaluate:

Foot alignment

Running mechanics

Hip strength

and

Muscle imbalance.

Strengthening

Rehabilitation commonly includes:

Core strengthening

Hip strengthening

and progressive lower-extremity:

Conditioning.

Medication

Acetaminophen

Acetaminophen is generally preferred for:

Pain control.

NSAIDs

NSAIDs may decrease pain, but their use in stress fracture is:

Controversial

because prostaglandin inhibition may theoretically impair:

Bone healing.

If used, prolonged or high-dose treatment is generally avoided when bone healing is a major concern.

Surgery

Surgery is primarily considered for:

High-risk stress fractures

or injuries that progress despite adequate:

Nonoperative treatment.

Femoral Neck Stress Fracture

Certain femoral neck stress fractures require:

Urgent surgical treatment.

Tension-Side Femoral Neck Lesions

Stress fractures along the:

Superolateral or tension side

of the femoral neck have a high risk of:

Completion and displacement.

These lesions often require:

Internal fixation.

Displaced Femoral Neck Fracture

A complete displaced femoral neck stress fracture is an:

Orthopaedic emergency

because displacement can disrupt blood supply to the:

Femoral head

and cause:

Avascular necrosis.

Other High-Risk Locations

Stress fractures associated with a greater risk of delayed union or nonunion include:

Anterior tibial cortex

Patella

Medial malleolus

Talus

Tarsal navicular

and

Proximal fifth metatarsal.

Anterior Tibial Stress Fracture

Anterior tibial stress fractures are tension-sided injuries and may show the classic:

Dreaded black line

on radiographs.

They have a greater risk of:

Delayed union and nonunion.

Tarsal Navicular

Navicular stress fractures are high risk because of:

Limited central blood supply

and substantial mechanical:

Loading.

Fifth Metatarsal

Proximal fifth-metatarsal stress fractures may heal slowly because of the:

Watershed blood supply.

Some athletes benefit from:

Early surgical fixation.

Referral

Orthopaedic or sports-medicine referral is appropriate for:

High-risk fracture sites

Persistent pain

Uncertain diagnosis

and suspected:

Metabolic bone disease.

Metabolic Referral

Patients with:

RED-S

Eating disorder

Menstrual dysfunction

Recurrent fractures

or unexplained low bone density may require multidisciplinary evaluation involving:

Sports medicine

Endocrinology

Nutrition

and other specialists.

Follow-Up

Clinical follow-up assesses:

Pain

Tenderness

Weight-bearing tolerance

and progression back to:

Activity.

Radiographic Monitoring

Repeat radiographs may be obtained approximately every:

4–6 weeks

when radiographic healing needs to be documented.

MRI Follow-Up

Routine repeat MRI is not required for every patient.

It may be useful when symptoms fail to improve or in selected:

High-risk injuries.

Prognosis

Most stress fractures in:

Young healthy individuals

have an excellent prognosis.

Older Patients

Patients with:

Osteoporosis

or other metabolic bone disease are more likely to develop subsequent:

Insufficiency fractures.

Reversible Bone Disorders

When an underlying problem such as:

Low energy availability

Vitamin D deficiency

or another treatable bone-health abnormality is corrected, the risk of future:

Stress injury

may decrease.

Return-to-Activity Time by MRI Grade

Historical estimates suggest progressively longer recovery with increasing:

MRI grade.

Grade I

Return to full activity may require approximately:

3 weeks or longer.

Grade II

Recovery may require approximately:

5 weeks or longer.

Grade III

Recovery may require approximately:

11 weeks or longer.

Grade IV

Recovery may require approximately:

14 weeks or longer.

These intervals are approximate and depend heavily on:

Fracture location

Symptoms

Bone health

and

Individual healing.

Complications

Completion of the Fracture

The most important complication is progression from a stress reaction or incomplete fracture to a:

Complete fracture.

This can substantially prolong:

Healing time

and may require:

Surgical fixation.

Displacement

Displacement is particularly dangerous at sites such as the:

Femoral neck.

It may result in:

Avascular necrosis

or major:

Functional loss.

Delayed Union and Nonunion

High-risk lesions may develop:

Delayed union

or

Nonunion.

This is particularly important in:

Anterior tibial

Navicular

and

Proximal fifth-metatarsal fractures.

Persistent Pain

Some patients continue to experience:

Pain

after radiographic fracture healing.

Persistent symptoms should prompt reassessment for:

Incomplete healing

Biomechanical abnormalities

or another diagnosis.

Recurrent Stress Injury

Failure to address:

Training errors

RED-S

Low bone density

or other risk factors may lead to:

Recurrent stress fractures.

Patient Monitoring

Patients should be monitored for:

Resolution of focal tenderness

Pain-free walking

Progressive load tolerance

and evidence of:

Fracture healing.

Return-to-Sport Criteria

Return to unrestricted activity is safest when the patient has:

No pain with daily activity

No focal tenderness

Pain-free impact loading

Restored strength

and correction of important:

Training or metabolic risk factors.

Key Principle

A stress fracture is a bone injury caused when repetitive mechanical loading exceeds the rate at which bone can remodel and repair itself.

In younger patients, this usually represents a:

Fatigue fracture of normal bone, whereas older or osteopenic patients may sustain an:

Insufficiency fracture from normal loading.

Early radiographs may be normal, while:

MRI is highly sensitive and is generally the preferred advanced imaging study.

Treatment centers on:

Reducing load below the pain threshold, protected weight bearing when needed, correcting training and biomechanical factors, and gradually returning to activity.

High-risk fractures, particularly involving the:

Femoral neck, anterior tibia, navicular, medial malleolus, talus, patella, or proximal fifth metatarsal

require more aggressive management because of the risk of:

Displacement, delayed union, nonunion, or avascular necrosis.