Bone and Joint Infections

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Bone and Joint Infections

• February 13, 2003
• Cass Djurfors

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Objectives

• Osteomyelitis
• Septic Arthritis
• Epidemiology
• Clinical features
• Diagnosis
• Management

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Epidemiology

• Bimodal age distribution
• Under 20
• Over 50
• Pediatrics
• boysgtgirls
• Usually no identifiable risk factors
• Adults
• Usually have risk factors

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Bone and Joint Infections Mechanism

• Hematogenous seeding most common
• Seeding from a contiguous source of infection
• Direct inoculation of the bone, from surgery,
  trauma or joint aspiration

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Risk factors for bone and joint infections

• diabetes mellitus
• sickle cell disease
• AIDS
• alcoholism
• IV drug abuse
• chronic corticosteroid use
• preexisting joint disease
• other immunosuppressed states
• postsurgical patientsespecially those with
  prosthetic devices

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Pathogens

• Bacteria are most common
• Viruses, fungi and parasites are possible
• Staph aureus most common in all ages except
  neonates
• GBS most common in neonates
• H. influenzae b has essentially disappeared as a
  pathogen in vaccinated children

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Pathogens

• Gonococcal arthritis is the most common type of
  septic arthritis in individuals under 30 years
  old
• In the elderly, gram-negative bacteria account
  for a higher percentage of cases of bone and
  joint infections than in younger people
• MRSA, MRSE, and VRE have emerged as a significant
  microbiologic problem in the past decade

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Pathogens

• Usually unimicrobial
• Polymicrobial (36 to 50) more likely in
  diabetic foot osteomyelitis, posttraumatic
  osteomyelitis, chronic osteomyelitis, and chronic
  septic arthritis

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Osteomyelitis Presentation

• May be acute or chronic
• Pain over the affected bone
• In children limp or refusal to weight
• Localized warmth, swelling, and erythema
• Fever is inconsistently present
• Systemic complaints often reported headache,
  fatigue, malaise, and anorexia

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Osteomyelitis Presentation

• Point tenderness over the infected segment
• Palpable warmth and soft-tissue swelling with
  erythema may be present

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Osteomyelitis Diagnosis

• WBC is neither sensitive nor specific
• Values commonly range from normal to 15,000/mm3
• ESR usually elevated
• One series reported 90 sensitivity
• Very nonspecific however
• Can be used to follow treatment
• CRP
• yet another nonspecific marker of inflammation

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Osteomyelitis Diagnosis

• Plain films
• Low sensitivity early in the disease
• 3-5 days may detect soft tissue edema
• 7-10 days gt66 still have normal x-rays
• 30-50 of bone mineral must be lost to detect
  lucency on plain film
• By 28 days, gt90 of plain films will be positive
• Characteristic finding lucent lytic lesions of
  cortical bone destruction
• Advanced disease lytic lesions are surrounded by
  dense, sclerotic bone, and sequestra may be noted

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Plain radiograph of tibia. Lucent areas in
metaphysis are sites of advanced osteomyelitis
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Plain radiograph of humerus. Distal portion of
humerus has involucrum formation, representing
advanced case of osteomyelitis.
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Osteomyelitis Diagnosis

• Bone Scan
• More useful early on than plain radiographs
• Can detect osteomyelitis within 48 to 72 hours of
  disease onset
• Sensitivity 90 with technetium-99 scan
• False positive rate as high as 64
• Trauma, surgery, tumours, soft tissue infection

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Example of gallium (top) and technetium (bottom)
bone scans in advanced osteomyelitis of tibial
metaphysis. Both scans show increased
radionuclide uptake.
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Osteomyelitis Diagnosis

• 111 In-labeled WBC scan
• Can distinguish infected bone from bone that has
  increased turnover from fractures, surgery,
  prostheses, osteoarthropathy, and tumor
• Usually reserved for situations of equivocal or
  normal bone scans in patients where osteomyelitis
  is still a consideration

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Osteomyelitis Diagnosis

• CT
• Used for infection in bones that are difficult to
  visualize on plain radiographs and bone scans
  sternum, vertebrae, pelvic bones, and calcaneus
• Appears as rarefaction, or lucent areas, on the
  CT scan images
• Gas may also be visible in bony abscess cavities
• Limitation disease must be present for gt 1 week

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Osteomyelitis Diagnosis

• MRI
• Good for early detection
• Limited availability

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Osteomyelitis Diagnosis

• Microbiologic Diagnosis
• Needle aspiration or surgical specimen is best
• Swab of draining wound or sinus is not adequate
• Blood cultures in untreated patients are positive
  50 of the time

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Differential Diagnosis

• Tumour
• Osteoid osteoma, chondroblastoma, Ewings
  sarcoma, metastases, lymphoma
• Trauma
• Myositis ossificans
• Erythema nodosum
• Cellulitis
• Eosinophilic granuloma

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Osteomyelitis Management

• IV Antibiotics
• Empiric broad spectrum initially
• Narrow appropriately when sensitivities available
• 4-6 weeks
• /- Surgical debridement
• Often not needed for acute hematogenous
  osteomyelitis in children
• Required in the diabetic foot or chronic
  osteomyelitis
• HBO
• Controversial

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Special considerations

• Kids usually acute hematogenous and often
  responds to Abx alone
• Vertebral osteomyelitis
• Risk of paralysis!
• Watch for epidural abscess
• Careful with back pain and fever in IVDU
• Post-traumatic osteomyelitis
• 10 of open fractures
• 2 with puncture wounds Pseudomonas aeruginosa
  and S. aureus

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Special considerations

• Diabetic foot
• Usually chronic and polymicrobial
• Surgical debridement almost always required
• Amputation often required
• Sickle cell disease
• Increased risk of osteomyelitis
• S. aureus and Salmonella species

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Empiric Therapy Adults CHA
Osteomyelitis Pathogen Therapy
Hematogenous S. aureus Cloxacillin or Cefazolin /- Gentamicin
IVDU S. aureus P. aeruginosa Cloxacillin or Cefazolin Gentamicin
Contiguous vascular insufficiency, diabetic foot Polymicrobial Clinda Cipro or Ancef Metronidazole Severe imipenem or pip-tazo
Nail-puncture of foot P. aeruginosa Prophylaxis cipro Treatmentpip-tazo tobramycin
Post-op prosthetic joint S. aureus S. epidermidis Vancomycin Gentamicin
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Empiric Therapy Kids CHA
Osteomyelitis Pathogen Therapy
Neonates GBS, S. aureus, Enterobacteriaceae Cloxacillin Cefotaxime
Children S. aureus, Strep, H. flu Cloxacillin
Sickle cell S. aureus, Salmonella sp. Cloxacillin Cefotaxime
Post-op S.aureus, GAS, Enterobacteriaceae Cefazolin /- Gentamicin
Post-op spinal rods or sternotomy S. aureus, CNS, GAS, Enterobacteriaceae, Pseudomonas Vancomycin Gentamicin
Nail puncture of foot Pseudomonas aeruginosa PiperacillinTobra or Ceftazidime Tobra
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Disposition

• Inpatient
• Outpatient IV antibiotic therapy
• Outpatient PO antibiotic therapy (usually as
  step-down)

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Septic Arthritis Presentation

• Usually hematogenous but may also result from
  contiguous spread or direct inoculation
• Occurs in all age groups
• Most common in children
• Usually monoarticular
• Polyarticular in less than 10 of pediatric cases
  and less than 20 of adult cases
• Hip and knee are most frequently affected

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Septic Arthritis Presentation

• Predisposing factors
• Any joint disease
• Osteoarthritis
• Gout
• Rheumatoid arthritis
• Surgery
• IVDU

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Septic Arthritis Presentation

• Usually acute in onset
• Joint pain is main feature worse with movement
  (careful with immunosuppressed and steroid
  dependent patients)
• Kids may refuse to use the affected limb
• Fever - 80 of children, gt 40 of adults

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Septic Arthritis Presentation

• Physical exam
• Joint is held in position of greatest comfort,
  slight flexion
• Swelling, erythema, and warmth in almost all
  cases
• Palpation of the septic joint causes exquisite
  pain
• Both flexion and extension of the joint cause
  severe pain
• Effusion

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Septic Arthritis Diagnosis

• Joint fluid for culture and analysis
• Knee joint is both the most likely to be infected
  and the easiest to aspirate in the ED
• Other joints (hip) may require ortho
  consultation /- ultrasound or fluoroscopy-guided
  aspiration
• Iatrogenic septic arthritis occurs in less than 1
  in 10,000 joint injections or aspirations

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Septic Arthritis Diagnosis

• Joint fluid
• aerobes, anaerobes and fungi
• Gram stain
• Cell count and differential - wbc gt 50000/mm3
• Glucose decreased in septic arthritis with
  joint fluid/serum glucose ratio lt 12.
• Synovial tissue from arthroscopy can be helpful
  in diagnosis

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Septic Arthritis Diagnosis

• Blood cultures positive in 25 to 50 of cases
• ESR elevated in 90
• WBC may or may not be elevated
• Plain radiographs not very helpful except to
  reveal joint effusion
• Bone scan will be hot but causes unnecessary
  delay

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Special Considerations

• Kids
• More common than osteomyelitis
• Of all cases in kiddies, 2/3 under age 2
• Neonates GBS, S. aureus, GNB
• gt3 months S. aureus gt GAS gt S. pneumo
• Teenagers and young adults
• N. gonorrhoeae
• Most are symptomatic with genital/oral infection
• Classic triad of disseminated gonococcal
  infection is migratory polyarthritis,
  tenosynovitis, and dermatitis
• Joint fluid may be negativetreat on suspicion

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Septic Arthritis Differential

• Kids
• Osteomyelitis
• JRA
• Transient synovitis
• Legg-Calvé-Perthes disease
• Slipped capital femoral epiphysis
• Rheumatic fever

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Septic Arthritis Differential

• Adults
• Osteomyelitis
• Gout
• Pseudogout
• Reiters syndrome
• Psoriatic arthritis
• Arthritis associated with inflammatory bowel
  disease and ankylosing spondylitis
• Traumatic hemarthrosis

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Septic Arthritis Management

• Orthopedic emergency
• Immediate IV Abx
• Needle vs. surgical decompression
• Abx alone in gonococcal arthritis only

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Septic Arthritis CHA Adults
Septic Arthritis Pathogen Antibiotics
Adults (native joint /- penetrating trauma) S. aureus, P. aeruginosa Cloxacillin or cefazolin /- gentamicin
Gonococcal N. gonorrhoeae Cefotaxime
Rheumatoid arthritis S. aureus, Strep sp, Enterobacteriaceae Cefazolin /- gentamicin
Prosthetic joint S. aureus, S. epidermidis, others Vancomycin gentamicin
IVDU S. aureus, P. aeruginosa Cloxacillin or cefazolin /- gentamicin
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Septic Arthritis Kids
Septic Arthritis Pathogen Antibiotics
Neonates GBS, S. aureus, Enterbacteriaceae Cloxacillin Cefotaxime
Children S. aureus, Strep sp., rarely H. flu lt5yrs cefuroxime gt5yrsCloxacillin or cefazolin
Sexually active N. gonorrhoeae Cefotaxime
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Septic Arthritis Disposition

• Diagnostic joint fluid aspirate or high clinical
  suspicion requires admission
• Non-diagnostic aspirates with equivocal clinical
  findings may be discharged home and re-evaluated
  in 24 hours
• Be conservative (consider admission) for patients
  with joint disease, prosthetic joints or
  immunosuppression and suspected septic arthritis