Orthopaedic Surgery - Pathological Fracture

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Basics

A pathological fracture is a fracture that occurs through abnormal or structurally weakened bone rather than normal bone.

The normal bone may have been replaced by:

Tumor

Cystic tissue

Fibrous tissue

Metabolic bone abnormality

or may simply have been:

Destroyed by the underlying disease process.

As a result, the affected bone may no longer tolerate normal physiologic loading.

A fracture may therefore occur during:

Ordinary activities of daily living

or after trauma that would normally be insufficient to fracture healthy bone.

The underlying process may be:

Benign

or

Malignant.

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Geriatric Considerations

In older adults, pathological fractures are most commonly associated with:

Metastatic carcinoma

Multiple myeloma

Lymphoma

Less commonly, the fracture may occur through a primary malignant bone tumor such as:

Chondrosarcoma

or

Undifferentiated pleomorphic sarcoma of bone, historically termed malignant fibrous histiocytoma.

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Pediatric Considerations

In children and adolescents, common benign causes include:

Unicameral bone cyst

Nonossifying fibroma

Fibrous dysplasia

Important malignant causes include:

Osteosarcoma

and

Ewing sarcoma.

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Prevention

A pathological fracture cannot always be prevented, particularly when the underlying lesion has not yet been diagnosed.

However, many patients experience:

Activity-related bone pain before fracture occurs.

When a destructive lesion is identified before fracture, reducing mechanical stress and considering prophylactic stabilization may prevent progression to a complete fracture.

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Epidemiology

The likely underlying diagnosis depends strongly on:

Patient age

Anatomic location

and

Radiographic appearance.

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Children and Adolescents

Common benign lesions associated with pathological fracture include:

Unicameral bone cyst, especially in the proximal humerus or proximal femur

Nonossifying fibroma

Fibrous dysplasia

Important malignant lesions include:

Osteosarcoma

Ewing sarcoma

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Adults

Benign causes include:

Giant cell tumor

Fibrous dysplasia

Malignant causes include:

Metastatic bone disease

Multiple myeloma

Lymphoma

Primary bone sarcoma

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Older Adults

In geriatric patients, malignant disease becomes increasingly important.

Common causes include:

Metastatic carcinoma

Multiple myeloma

Lymphoma

Less common primary skeletal malignancies include:

Chondrosarcoma

Undifferentiated pleomorphic sarcoma

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Risk Factors for Impending Fracture

Fracture risk increases as destruction of the:

Cortex

and

Overall structural integrity

progresses.

Historically, destruction of more than approximately:

50% of the cortical diameter

has been considered a major risk factor for pathological fracture.

Assessment should be made using:

AP and lateral radiographs

and, when necessary,

CT.

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Role of CT in Fracture-Risk Assessment

CT can define:

Cortical destruction

Lesion length

Circumferential bone involvement

Remaining structural bone

more accurately than plain radiographs in selected patients.

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Genetics

There is no single genetic abnormality associated with pathological fracture itself.

Genetic factors depend on the:

Underlying bone disorder or neoplasm.

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Pathophysiology

Normal long-bone strength depends heavily on:

Cortical thickness

Bone diameter

Bone geometry

Trabecular architecture

Any process that destroys or replaces normal bone reduces its ability to withstand:

Bending

Compression

Torsion

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Cortical Destruction

Experimental data demonstrate that substantial cortical involvement can dramatically decrease bone strength.

Historically:

Approximately 50% symmetric cortical involvement has been associated with about a 60% reduction in bending strength.

Approximately 50% asymmetric cortical involvement may reduce strength by as much as 90%.

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Lesion Length

Long lytic lesions are particularly dangerous.

A defect whose length exceeds approximately:

The diameter of the involved bone

may result in major loss of:

Torsional strength.

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Associated Conditions

Any condition that sufficiently replaces or weakens normal bone can predispose to pathological fracture.

Examples include:

Bone metastases

Multiple myeloma

Primary bone tumors

Bone cysts

Fibrous dysplasia

Metabolic bone disease

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Diagnosis

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Signs and Symptoms

The two most important findings are:

Bone pain

and

Localized bone tenderness.

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Pain Before Fracture

Before a complete fracture occurs, patients may report:

Moderate or severe pain during weight bearing or activity.

This pain may initially be:

Intermittent

and later become:

Present with nearly all activity.

Persistent focal bone pain in a patient with a known destructive lesion should raise concern for:

Impending pathological fracture.

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Pain After Fracture

Once a complete fracture occurs, patients usually develop:

Sudden severe pain

which is worsened markedly by:

Movement

Weight bearing

or

Palpation.

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History

Important historical features include:

Duration of pain

Relationship of pain to activity

Known cancer diagnosis

Previous radiation therapy

Previous skeletal lesions

Recent weight loss or constitutional symptoms

Prior fractures

Minimal-trauma mechanism

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Physical Examination

Before fracture, examination may be:

Nearly normal.

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Tenderness

Palpation may reveal:

Localized bone tenderness.

Marked tenderness over a known lesion suggests:

Mechanical weakness or impending fracture.

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Soft-Tissue Mass

A palpable mass may be present in:

Primary malignant tumors

or

Aggressive metastatic lesions with cortical breakthrough.

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Range of Motion

Joint motion should be assessed:

Gently.

Forceful examination should be avoided because an unstable lesion may fracture during manipulation.

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Neurovascular Examination

A complete examination should assess:

Motor function

Sensation

Distal pulses

particularly when a large mass or displaced fracture is present.

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Laboratory Tests

Laboratory testing is guided by the suspected underlying cause.

Although laboratory studies do not diagnose the fracture itself, they may help identify:

Multiple myeloma

Metabolic bone disease

Hypercalcemia

Renal dysfunction

Anemia

or other systemic abnormalities.

Potential tests include:

CBC

Calcium

Creatinine

Alkaline phosphatase

Serum protein electrophoresis

Serum free light chains

and other investigations based on clinical suspicion.

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Imaging

Imaging is central to the evaluation.

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Plain Radiographs

AP and lateral radiographs of the entire involved bone are usually the:

First diagnostic study.

They should assess both:

The fracture

and

The underlying lesion.

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Radiographic Features

Important findings include:

Lytic bone destruction

Sclerosis

Cortical thinning

Cortical breakthrough

Periosteal reaction

Soft-tissue mass

Matrix mineralization

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Host Bone Reaction

A benign-appearing lesion may demonstrate:

A sclerotic rim

Cortical thickening

Well-defined margins

Aggressive lesions are more likely to demonstrate:

Poorly defined margins

Cortical destruction

Soft-tissue extension

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CT

CT may help determine:

The pattern of cortical destruction

Amount of remaining bone

Mineralized tumor matrix

Fracture configuration

Extent of a soft-tissue mass

It can also assist with:

Biopsy planning

and

Operative planning.

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MRI

MRI is particularly useful for evaluating:

Marrow involvement

Soft-tissue extension

Relationship to neurovascular structures

Extent of a primary bone tumor

Associated skip lesions in selected sarcomas

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Whole-Bone Imaging

When a malignant bone tumor is suspected, the entire involved bone should be imaged to evaluate for:

Additional lesions

and to assist with planning of:

Biopsy and definitive resection.

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Diagnostic Strategy

The diagnostic pathway depends heavily on whether the lesion appears:

Benign

or

Malignant/aggressive.

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Lesion With Malignant Features

When radiographs suggest malignancy, staging should be performed before definitive biopsy whenever possible.

This may include:

CT of the chest

Additional body imaging based on suspected primary tumor

Whole-body skeletal staging

MRI of the lesion

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Search for a Primary Carcinoma

In an adult with an unknown destructive bone lesion, evaluation may include imaging of:

Chest

Abdomen

Pelvis

and other investigations guided by the suspected primary malignancy.

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Biopsy

If biopsy is required, it should be performed:

After appropriate staging

and with the biopsy tract planned so that it can be removed during definitive tumor surgery if necessary.

Biopsy should ideally be coordinated by:

An orthopaedic oncologist or musculoskeletal tumor team.

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Benign-Appearing Lesions

When radiographs are characteristic of a known benign lesion such as:

Unicameral bone cyst

Nonossifying fibroma

Fibrous dysplasia

treatment may sometimes proceed without biopsy.

If the diagnosis is uncertain, tissue diagnosis is appropriate before definitive treatment.

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Pathological Findings

Histologic findings depend entirely on:

The underlying lesion.

The fracture itself may demonstrate:

Hemorrhage

Callus formation

Reactive bone

superimposed on the pathologic process.

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Differential Diagnosis

The differential diagnosis depends primarily on:

Age

Anatomic site

Radiographic appearance

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Young Patient With Benign-Appearing Lesion

Consider:

Unicameral bone cyst

Nonossifying fibroma

Fibrous dysplasia

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Young Patient With Aggressive Lesion

Consider:

Osteosarcoma

Ewing sarcoma

Osteomyelitis

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Adult With Aggressive Lesion

Consider:

Metastatic carcinoma

Multiple myeloma

Lymphoma

Primary bone sarcoma

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Treatment

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Initial Stabilization

Many patients experience pain for:

Weeks to months before fracture.

When activity-related pain is present in a bone containing a destructive lesion, loading should be reduced promptly.

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Walking Aids

Depending on the site and severity, options include:

Walker

Two crutches

Cane

Wheelchair

The goal is to reduce:

Mechanical load through the weakened bone.

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Bed Rest

Bed rest should generally be minimized when possible because prolonged immobility causes:

Deconditioning

Venous thromboembolism risk

Pressure injury

However, temporary bed rest may be required when:

Pain cannot be controlled

or

The fracture is mechanically unstable.

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General Measures

Initial priorities include:

Pain control

Protection of the affected extremity

Establishment of the underlying diagnosis

Prevention of further displacement

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Activity

Activity should be reduced according to:

Fracture stability

Pain

Location

Risk of progression

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Nursing Care

Important measures include:

Safe transfer techniques

Provision of walking aids

Fall prevention

Skin care

Pain management

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Radiotherapy

Radiotherapy is frequently used for selected malignant lesions, particularly:

Metastatic bone disease

Multiple myeloma

Lymphoma

It may be given:

After surgical stabilization

or, in selected nonfractured lesions, as part of nonsurgical treatment.

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Physical Therapy

Physical therapy is useful both:

Before

and

After surgery.

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Before Stabilization

Therapy focuses on:

Protected weight bearing

Use of assistive devices

Safe transfers

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After Stabilization

Rehabilitation focuses on:

Restoring mobility

Strengthening

Gait training

Safe use of walking aids

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Medication

Analgesics are used as required for:

Pain control.

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Bone-Targeted Therapy

Patients with selected metastatic bone disease or multiple myeloma may receive:

Bisphosphonates

or

Denosumab

to reduce skeletal complications.

These medications do not mechanically stabilize an established fracture.

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Surgery

Surgical treatment depends on:

Location of the fracture

Underlying diagnosis

Expected survival

Bone quality

Extent of disease

Ability of the fracture to heal

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Internal Fixation

Many pathological fractures of long bones are stabilized with:

Intramedullary fixation

because a nail can protect a long segment of diseased bone.

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Principles of Fixation

When metastatic disease is present, fixation should generally be designed to provide:

Immediate and durable mechanical stability

rather than relying entirely on biological fracture healing.

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Femoral Neck Fracture

Pathological fractures of the femoral neck are often treated with:

Arthroplasty

rather than internal fixation because healing may be unreliable.

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Metastatic Bone Disease

Depending on the location and bone destruction, reconstruction may include:

Intramedullary nail

Plate fixation with cement augmentation

Endoprosthetic replacement

Arthroplasty

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Primary Bone Sarcoma

A pathological fracture through a primary bone sarcoma requires a different strategy from metastatic disease.

Patients with tumors such as:

Osteosarcoma

or

Ewing sarcoma

should be managed by a:

Musculoskeletal oncology team.

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Sarcoma-Associated Fractures

Initial management may include:

Immobilization or casting

followed by:

Systemic chemotherapy when indicated

and subsequent:

Wide oncologic resection.

A pathological fracture does not automatically mandate amputation, but it may make limb-salvage surgery more complex because of potential contamination of surrounding tissues.

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Prophylactic Stabilization

A destructive lesion at high risk for fracture may be treated surgically:

Before a complete fracture occurs.

Prophylactic fixation is often preferable to treating a completed fracture because it may allow:

Less pain

Shorter hospitalization

Faster mobilization

Simpler reconstruction

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Follow-Up

Follow-up depends on:

The underlying lesion

Type of fixation

Expected healing potential

Oncologic treatment plan

For fractures expected to heal, radiographs may be obtained periodically, often at approximately:

4–6-week or 1-month intervals initially.

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Referral

Any pathological fracture associated with:

An unexplained destructive bone lesion

Possible primary bone tumor

or

Uncertain diagnosis

should be referred promptly to:

An orthopaedic oncologist.

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Prognosis

The prognosis depends primarily on:

The underlying disease, not the fracture itself.

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Benign Lesions

Pathological fractures through benign lesions generally have an:

Excellent prognosis, particularly once the lesion and fracture are appropriately treated.

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Metastatic Disease

Prognosis varies markedly according to:

Primary cancer type

Extent of metastatic disease

Response to systemic treatment

Older survival estimates such as 6–12 months for lung or kidney cancer and 24–48 months for breast or prostate cancer should not be applied rigidly to individual patients because modern systemic therapies have substantially changed outcomes in many cancers.

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Multiple Myeloma

Historically, median survival was only a few years, but modern systemic therapy has significantly improved survival for many patients.

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Lymphoma

Outcome depends strongly on:

Histologic subtype

Stage

Response to therapy

and should not be estimated from bone involvement alone.

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Osteosarcoma

Localized osteosarcoma treated with:

Chemotherapy and wide resection

has substantially better survival than in the pre-chemotherapy era, whereas metastatic disease carries a worse prognosis.

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Complications

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Infection

Operative stabilization may be complicated by:

Superficial or deep infection.

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Delayed Wound Healing

Patients with:

Malignancy

Prior radiation

Malnutrition

Chemotherapy exposure

may be at increased risk of:

Delayed wound healing.

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Failure of Union

Some pathological fractures heal poorly because of:

Extensive tumor replacement

Radiation damage

Poor vascularity

Systemic disease

Ongoing malignant activity

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Implant Failure

If the construct is not sufficiently durable or if disease progresses, complications may include:

Nail or plate failure

Loosening

Periprosthetic fracture

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Disease Progression

The underlying tumor may progress locally despite fracture stabilization.

Therefore, mechanical treatment should be integrated with:

Oncologic therapy.

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Patient Monitoring

Patients should be monitored for:

Pain control

Fracture stability

Healing when expected

Implant integrity

Progression of the underlying lesion

New metastatic disease

Functional recovery

The follow-up interval should be individualized rather than automatically limited to a fixed monthly schedule.

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Key Principle

A pathological fracture is a fracture through structurally abnormal bone that has been weakened by a benign, malignant, or metabolic process.

The most important management principle is:

Do not treat the fracture without first determining the underlying diagnosis.

When malignancy is possible, appropriate staging and biopsy planning should precede definitive fixation whenever circumstances allow.

Treatment combines:

Protection or stabilization of the weakened bone, management of the underlying disease, pain control, and restoration of safe mobility.