Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Vertebral Osteomyelitis

Basics

Description
Infection of the vertebral bony elements, not including the disc space
General Prevention
  • Prevention of HIV and hepatitis
  • Early treatment of hematogenous infection
  • Postoperative wound care, including dressing changes and prophylactic postsurgical antibiotics
Epidemiology
  • Bimodal distribution:
    • Small peak in youth (10-20 years old)
    • Largest peak in adults >50 years old
  • Increasing rates in young adults with HIV or other immunocompromise
  • Males affected more than females (60-80% of cases)
Incidence
Rare: 1 per 250,000
Prevalence
2-8% of all osteomyelitis cases
  • HIV
  • Diabetes
  • Organ transplant recipient
  • Spine surgery
  • Intravenous drug use
  • Immunosuppression
  • Alcoholism
Genetics
No known Mendelian genetic association
Pathophysiology
  • Thought to be primarily secondary to vascular spread of pathogens:
    • Most spinal infections originate from a hematogenous source.
    • The spine’s large venous and arterial circulation at both endplates and body facilitates hematogenous spread.
  • In postoperative patients with hardware, bacteria may adhere to instrumentation via glycocalyx and develop into osteomyelitis.
Etiology
  • Staphylococcus aureus: Most common pathogen
  • Pseudomonas: Seen in immunocompromised patients and those with a history of intravenous drug use
  • Klebsiella, Escherichia coli, and Proteus may be seen in patients with previous genitourinary infection and subsequent vertebral osteomyelitis.
  • Postoperative infections usually are caused by S. aureus and have a higher rate of antibiotic resistance than do infections from other organisms.
  • Mycobacterium tuberculosis (Potts disease) is now rare, but it can occur in developing countries and in immunocompromised patients.
Associated Conditions
  • Epidural abscess
  • HIV
  • Intravenous drug abuse
  • Discitis
  • Paravertebral abscess
  • Meningitis
  • Myelitis
  • Sepsis
Diagnosis
Signs and Symptoms
  • Back pain is the most common presenting symptom.
  • Constitutional symptoms of infection, including fever, anorexia, night sweats, chills
  • Spinal deformity in late cases secondary to bony destruction
  • Postoperative infections may show discharge and purulence from incision.
History
  • Back pain: Insidious but may be acute
  • Fever
  • Chills, night sweats
  • Irritability and fussiness in children
  • Neurologic deficits may occur in rare cases.
Physical Exam
  • Paraspinal tenderness and muscle spasm
  • Torticollis
  • Generalized weakness
  • Kernig sign and symptoms of meningitis
  • Hamstring spasm
  • Many clinical findings of infection may be reduced or absent in immunocompromised patients.
Tests
Lab
  • Complete blood count with differential may be elevated in 50% of patients.
  • ESR is the most sensitive marker for infection.
    • Normal rate is 0-20
    • Elevated in 90% of patients with infection, but also elevated postoperatively and thus lacks the specificity on its own for confident diagnosis
  • C-reactive protein is a more specific marker of acute infection.
    • Returns to normal 6-10 days postoperatively
    • Thus, an elevated rate for >10 days is suspicious for infection.
  • Blood cultures
  • Fungal cultures
  • History-driven specific labs such as exposure to tuberculosis
Imaging
  • Conventional radiography:
    • Changes on radiographs occur late, and initial radiographs may be normal.
    • If clinically suspicious, obtain MRI.
  • MRI:
    • Best study: Low on T1-weighted scans, high on T2-weighted scans
    • Post-gadolinium images show ring-enhanced areas of signal intensity.
  • CT scan: Osteolysis

P.479
Diagnostic Procedures/Surgery
  • Nuclear medicine studies are useful in MRI-contraindicated patients (e.g., those with pacemakers)
  • Bone scan
  • Indium-labeled white blood cell count:
    • High false-negative rate
    • Do not use as stand-alone test.
  • Biopsy: Percutaneous or open at the time of surgery
Pathological Findings
  • Biopsy material may contain organisms:
    • Inflammatory cells
    • Caseating necrotic granulomas in patients with tuberculosis
Differential Diagnosis
  • Fracture
  • Tumor
  • Disc herniation
  • Infections:
    • Typically cross the endplate
    • Tumor usually spares the endplate (per MRI).
Treatment
Initial Stabilization
  • Intravenous antibiotics:
    • Initially, broad spectrum until organism sensitivities are obtained, and the specific antibiotics can be administered.
  • Spine immobilization
General Measures
  • Obtain cultures of blood and, if possible, bone before starting antibiotics.
  • Biopsy is critical for treatment: Should attempt percutaneously if possible.
  • Immobilize spine.
Activity
  • Bed rest
  • Thoracolumbosacral orthotic for immobilization, if needed
Nursing
  • Patients may be critically ill and may require intensive care.
  • Patients should be hospitalized for intravenous administration of antibiotics and for observation and management of medical comorbidities.
Special Therapy
Physical Therapy
  • No role for physical therapy in acute infection
  • Increased pain postoperatively with physical therapy may be a signal of infection.
Medication
First Line
Broad-spectrum antibiotics
Second Line
  • After biopsy, culture-specific antibiotics:
    • Vancomycin for methicillin-resistant organisms
  • Zosyn (piperacillin and tazobactam) for Pseudomonas and Gram-negative organisms
Surgery
  • Indications for surgical management:
    • Failure of nonoperative treatment
    • Need for open biopsy
    • Presence of spinal abscess
    • Sepsis
    • Progressive spinal deformity
    • Refractory pain
    • Spinal Instability
    • Neurologic deficit
  • Surgical treatment principles in infection are:
    • Adequate débridement
    • Neurologic decompression if needed
    • Rigid fixation
Follow-up
  • Continue intravenous antibiotics for 6–8 weeks.
  • Follow-up with infectious-disease specialist.
  • Early and progressive mobilization
Complications
  • Abscess formation
  • Vertebral collapse
  • Neurologic compromise
  • Paralysis
  • Cauda equina syndrome
  • Untreated infections may lead to sepsis and possible death.
Patient Monitoring
  • Repeat radiographs every 4-8 weeks until radiographically and clinically stable.
  • Follow-up ESR and C-reactive protein
  • Repeat MRI if pain or fever continues.
Miscellaneous
Codes
ICD9-CM
730.28 Vertebral osteomyelitis
Patient Teaching
  • Early treatment of infectious processes, especially in immunocompromised patients.
  • It is essential that patients complete the course of intravenous antibiotics.
Activity
  • Immobilization in acute phase with brace
  • Early mobilization after surgical stabilization
FAQ
Q: Is emergent surgery indicated once the diagnosis of vertebral osteomyelitis is suspected?
A: The 1st-line treatment for this condition is intravenous antibiotics and immobilization. Surgery is indicated in the presence of neurologic deficit, worsening pain, deformity, or the presence of an epidural abscess.
Q: Is neurologic compromise the most common presenting symptom in patients with vertebral osteomyelitis?
A: No. Neurologic compromise actually is quite rare. One should suspect possible vertebral osteomyelitis in immunocompromised or postsurgical patients with worsening back and spine pain. Appropriate imaging and laboratory studies should be obtained.

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