Orthopaedic Surgery - Vertebral Osteomyelitis

Basics

Vertebral osteomyelitis is an infection involving the:

Vertebral body and other spinal bony elements

and may also involve the adjacent:

Intervertebral disc space.

When the disc and adjacent vertebral endplates are both involved, the process is often referred to as:

Spondylodiscitis.

General Prevention

Preventive measures include:

Prompt treatment of bloodstream infections

Appropriate postoperative wound care

and reduction of risk factors for:

HIV, hepatitis, and injection-related infections.

Postoperative Prevention

After spine surgery, prevention includes:

Sterile wound care

Appropriate dressing changes

and indicated:

Perioperative antibiotic prophylaxis.

Epidemiology

Vertebral osteomyelitis has a:

Bimodal age distribution.

A smaller peak occurs in:

Adolescents and young adults

while the largest burden occurs in adults older than approximately:

50 years.

Immunocompromised Patients

Rates are higher in people with:

HIV

Immunosuppression

or other conditions that impair:

Host defense.

Sex

Males are affected more frequently than females, historically accounting for approximately:

60–80% of cases.

Incidence

Vertebral osteomyelitis is:

Rare.

Historical estimates have been approximately:

1 case per 250,000 persons.

Proportion of Osteomyelitis

Spinal infection represents roughly:

2–8% of all osteomyelitis cases

in historical series.

Risk Factors

Important risk factors include:

HIV

Diabetes mellitus

Organ transplantation

Recent spine surgery

Intravenous drug use

Immunosuppression

and

Alcohol misuse.

Genetics

There is no recognized:

Mendelian genetic association

for typical vertebral osteomyelitis.

Pathophysiology

Most vertebral infections arise through:

Hematogenous spread.

Hematogenous Seeding

The vertebral bodies have a rich:

Arterial and venous blood supply

particularly near the:

Endplates.

This facilitates deposition of circulating:

Microorganisms.

Endplate and Disc Involvement

In adults, infection often begins near the:

Vertebral endplate

and then spreads across the disc space to the adjacent:

Vertebral body.

Postoperative Infection

After spinal instrumentation, bacteria may adhere to hardware and form:

Biofilm.

This can make infection more resistant to:

Antibiotic therapy

and host:

Immune clearance.

Etiology

The most common causative organism is:

Staphylococcus aureus.

MRSA

Methicillin-resistant:

S. aureus

is an important consideration, particularly in:

Postoperative

Healthcare-associated

and high-risk infections.

Pseudomonas

Pseudomonas aeruginosa

is more frequently associated with:

Injection drug use

and some:

Immunocompromised patients.

Gram-Negative Organisms

Organisms such as:

Klebsiella

Escherichia coli

and

Proteus

may occur following:

Genitourinary infection

or bacteremia.

Postoperative Infection

Postoperative spinal infections are commonly caused by:

S. aureus

and may involve organisms with increased:

Antibiotic resistance.

Tuberculosis

Mycobacterium tuberculosis

can cause vertebral osteomyelitis, classically called:

Pott disease.

This is less common in many developed settings but remains important in:

Endemic regions

and

Immunocompromised patients.

Associated Conditions

Potential associated complications and conditions include:

Epidural abscess

Discitis

Paravertebral abscess

Meningitis

Myelitis

Sepsis

HIV

and

Intravenous drug use.

Diagnosis

Diagnosis depends on:

Clinical suspicion

Inflammatory markers

Blood cultures

and

Imaging.

Signs and Symptoms

The most common presenting symptom is:

Back pain.

Pain Pattern

Pain is often:

Insidious

Persistent

and

Progressive.

It may occasionally begin:

Acutely.

Constitutional Symptoms

Patients may also have:

Fever

Chills

Night sweats

Anorexia

and

Weight loss.

Children

Children may present with:

Irritability

Fussiness

Refusal to walk

or nonspecific:

Back discomfort.

Neurologic Deficit

Neurologic deficits are less common but may occur with:

Epidural extension

Cord compression

or

Cauda equina involvement.

Deformity

Advanced disease can cause:

Vertebral destruction

leading to:

Kyphosis

or other:

Spinal deformity.

Postoperative Infection

Postoperative infection may present with:

Wound drainage

Purulence

Persistent pain

or

Failure of expected recovery.

Physical Examination

Common findings include:

Paraspinal tenderness

and

Muscle spasm.

Cervical Infection

Cervical infection may produce:

Torticollis

or painful limitation of:

Neck movement.

General Weakness

Systemic illness may produce:

Fatigue

and

Generalized weakness.

Meningeal Signs

When meningeal irritation is present, findings such as:

Kernig sign

may be positive.

Hamstring Spasm

Children may develop:

Hamstring spasm

or reluctance to flex the spine.

Immunocompromised Patients

Classic inflammatory findings may be:

Blunted or absent

in immunocompromised patients.

A lack of fever does not exclude:

Spinal infection.

Laboratory Tests

Complete Blood Count

The white blood cell count may be elevated, but this occurs in only about:

Half of patients

in some series.

A normal CBC does not exclude:

Vertebral osteomyelitis.

ESR

The:

Erythrocyte sedimentation rate

is highly sensitive for spinal infection.

It is elevated in approximately:

90% of patients

in historical series.

Limitation of ESR

ESR is nonspecific and may also remain elevated following:

Surgery

or in other inflammatory conditions.

CRP

C-reactive protein

is useful for:

Diagnosis

and

Monitoring treatment response.

Postoperative CRP

After uncomplicated surgery, CRP usually falls toward normal within approximately:

6–10 days.

Persistent or secondary elevation should raise concern for:

Infection.

Blood Cultures

Blood cultures should be obtained before antibiotics whenever:

Clinically feasible.

They may identify the pathogen and allow earlier:

Culture-directed therapy.

Additional Cultures

Selected patients may require:

Fungal cultures

or testing for:

Tuberculosis

depending on exposure and risk profile.

Imaging

Plain Radiographs

Early radiographs may be:

Normal.

Radiographic abnormalities usually appear:

Late.

Late Radiographic Findings

Possible findings include:

Endplate erosion

Disc-space narrowing

Vertebral body destruction

and eventually:

Collapse or fusion.

MRI

MRI is the:

Preferred imaging study.

MRI Signal

Typical findings include:

Low signal on T1-weighted images

and

High signal on T2-weighted or fluid-sensitive sequences.

Contrast Enhancement

Post-gadolinium imaging may demonstrate:

Endplate enhancement

Disc enhancement

Paravertebral inflammation

or

Abscess formation.

Epidural Disease

MRI is particularly important for evaluating:

Epidural abscess

and

Neural compression.

CT

CT may demonstrate:

Osteolysis

Cortical destruction

and

Bony collapse.

It is also useful for guiding:

Percutaneous biopsy.

Nuclear Medicine

When MRI cannot be performed, nuclear medicine imaging may be considered.

Options include:

Bone scintigraphy

and other:

Infection-sensitive studies.

Biopsy

Image-guided:

Percutaneous biopsy

is often important in adults when the organism has not been identified from:

Blood cultures.

Open Biopsy

Open biopsy may be required when:

Percutaneous biopsy is nondiagnostic

or when surgery is already indicated for:

Decompression or debridement.

Pediatric Cases

In a child with a highly characteristic clinical and imaging picture, biopsy may not always be:

Necessary.

Pathological Findings

Biopsy may demonstrate:

Inflammatory cells

and sometimes the causative:

Microorganisms.

Tuberculosis Histology

Tuberculous infection may show:

Caseating granulomas

and

Necrosis.

Differential Diagnosis

Important alternatives include:

Vertebral fracture

Tumor

Disc herniation

and other causes of:

Back pain.

Infection Versus Tumor

Spinal infection typically involves the:

Endplate and adjacent disc space.

In contrast, many tumors initially:

Spare the disc space.

This distinction is helpful but not:

Absolute.

Treatment

Management depends on:

Organism

Neurologic status

Spinal stability

and presence of:

Abscess or sepsis.

Initial Stabilization

Initial treatment typically includes:

Antibiotic therapy

and, when needed,

Spinal immobilization.

Culture Before Antibiotics

When the patient is clinically stable, obtain:

Blood cultures

and ideally:

Tissue cultures

before starting antibiotics.

Exception

Antibiotics should not be delayed in patients with:

Sepsis

Hemodynamic instability

or rapidly progressive:

Neurologic compromise.

Empiric Antibiotics

Initial therapy may require:

Broad-spectrum intravenous antibiotics

until culture and sensitivity results become available.

Culture-Directed Therapy

Once the pathogen is known, treatment should transition to:

Targeted antimicrobial therapy.

Immobilization

A brace may help control:

Pain

and protect against:

Instability.

TLSO

Thoracolumbar infection may occasionally require a:

Thoracolumbosacral orthosis

for support.

Activity

During the acute painful phase, activity may need to be:

Restricted.

Bed Rest

Short-term bed rest may be required in patients with:

Severe pain

or

Instability.

Prolonged immobility should be avoided when possible because of the risks of:

Deconditioning

and

Venous thromboembolism.

Hospitalization

Many patients initially require:

Hospital admission

for intravenous antibiotics and monitoring of:

Neurologic status

Sepsis

and

Medical comorbidities.

Physical Therapy

Rehabilitation begins once pain and spinal stability permit:

Progressive mobilization.

Postoperative Warning Sign

Unexpected worsening pain during postoperative therapy may indicate:

Deep infection

and should prompt:

Reassessment.

Medication

Empiric therapy should cover likely:

Gram-positive organisms

and, when risk factors exist,

Gram-negative organisms.

MRSA Coverage

Vancomycin

is commonly used when coverage for:

MRSA

is required.

Gram-Negative Coverage

Agents with antipseudomonal and Gram-negative activity, such as:

Piperacillin-tazobactam

may be considered in selected patients.

Definitive therapy should be based on:

Culture results

and infectious-disease guidance.

Surgery

Most uncomplicated cases can be treated:

Nonoperatively.

Surgery is reserved for specific:

Indications.

Indications for Surgery

Potential indications include:

Failure of antibiotic treatment

Need for diagnostic open biopsy

Epidural or paravertebral abscess

Sepsis

Progressive spinal deformity

Persistent severe pain

Mechanical instability

and

Neurologic deficit.

Surgical Principles

The major goals are:

Adequate debridement

Neural decompression when required

and

Restoration of spinal stability.

Instrumentation

Rigid fixation may be required when infection has produced:

Instability

or major structural:

Destruction.

Instrumentation can be used in infected fields when combined with:

Appropriate debridement and antimicrobial treatment.

Follow-Up

Antibiotic therapy is commonly continued for approximately:

6 weeks

and sometimes longer depending on:

Organism

Extent of infection

and clinical response.

Historical protocols often used:

6–8 weeks of intravenous therapy.

Modern regimens may include an earlier transition to highly bioavailable:

Oral antibiotics

in selected patients.

Infectious-Disease Follow-Up

Management is often coordinated with an:

Infectious-disease specialist.

Mobilization

As symptoms improve, patients should undergo:

Early progressive mobilization.

Prognosis

Most patients improve with:

Timely diagnosis

and

Appropriate antimicrobial therapy.

Outcome is less favorable when diagnosis is delayed or when there is:

Neurologic injury

Sepsis

or major:

Spinal destruction.

Complications

Important complications include:

Epidural or paravertebral abscess

Vertebral collapse

Autofusion

Neurologic compromise

Paralysis

and

Cauda equina syndrome.

Abscess Formation

Infection may extend into:

Paravertebral

or

Epidural spaces.

An epidural abscess can rapidly threaten:

Neural structures.

Vertebral Collapse

Progressive bone destruction may result in:

Compression deformity

and

Kyphosis.

Spontaneous Fusion

Healing may lead to:

Disc-space loss

and eventual:

Intervertebral autofusion.

Neurologic Compromise

Cord, nerve-root, or cauda equina compression can produce:

Weakness

Sensory loss

Bowel or bladder dysfunction

or

Paralysis.

Patient Monitoring

Follow-up should include:

Clinical symptoms

Neurologic examination

and

Inflammatory markers.

Serial Laboratory Monitoring

Trend:

CRP

and

ESR

to assess response to:

Treatment.

CRP generally changes more rapidly than:

ESR.

Follow-Up Imaging

Plain radiographs may be repeated every approximately:

4–8 weeks

until the spine is clinically and structurally:

Stable.

Repeat MRI

Repeat MRI is not routinely necessary if the patient is improving.

It should be considered when there is persistent or worsening:

Pain

Fever

Neurologic deficit

or concern for:

Abscess or treatment failure.

Clinical Summary

Typical presentation: Insidious, progressive back pain, sometimes with fever, night sweats, chills, or weight loss.

Most common organism: Staphylococcus aureus.

Major risk factors: Diabetes, immunosuppression, IV drug use, HIV, recent spine surgery, and bacteremia.

Key laboratory tests: ESR and CRP are usually elevated; obtain blood cultures before antibiotics when feasible.

Best imaging: MRI with contrast is the preferred study and assesses vertebral infection, disc involvement, epidural abscess, and neural compression.

Biopsy: CT-guided biopsy is important in adults when blood cultures do not identify the organism.

Treatment: Usually culture-directed antibiotics, with bracing or temporary activity restriction as needed.

Surgery: Required for neurologic deficit, instability, progressive deformity, abscess with compression, sepsis, refractory pain, or failure of medical treatment.

Major complications: Epidural abscess, vertebral collapse, deformity, paralysis, and cauda equina syndrome.

Key Principle

Vertebral osteomyelitis is usually a hematogenous infection of the vertebral body and adjacent endplates, often extending into the disc space.

The most common presentation is:

Persistent back pain, while fever may be absent, especially in:

Immunocompromised patients.

The most useful diagnostic combination is:

Inflammatory markers, blood cultures, and MRI with contrast.

Most patients can be treated with:

Prolonged culture-directed antimicrobial therapy, while surgery is reserved for:

Neurologic compromise, abscess, instability, progressive deformity, sepsis, or failure of nonoperative treatment.

Close follow-up is necessary to detect:

Persistent infection, collapse, deformity, or neurologic deterioration.