Osteomyelitis

• Osteomyelitis


  • Progressive inflammatory destruction
  • Apposition of new bone
• Pathophysiology of Osteomyelitis

  1. Bacteria introduced by blood/trauma to bone

  2. Inflammatory reaction and release of lytic enzymes

  3. Local ischemic necrosis pus collection and abscess formation

  4. Increased intramedullary pressure

  5. Cortical ischemia

  6. Purulent material escapes through thin cortex into subperiosteal space subperiosteal abscess formation
• Routes of infection for Osteomyelitis

  • Hematogenous spread: more common in children
  • Direct inoculation (post-traumatic): more common in adults
  • Contiguous spread: From adjacent septic arthritis/prosthesis/soft tissue infection(ulcer in a diabetic foot)
• Causative microorganisms for Osteomyelitis

  • Staphylococcus aureus
  • Salmonella in sickle cell disease patients
  • Gram-negative bacilli (e.g. E. coli, Klebsiella) mainly affect neonates
  • Group B streptococci cause osteomyelitis mainly in young infants
  • Pseudomonas aeruginosa causes osteomyelitis mainly in IV drug users
• Affected Bones in Osteomyelitis

  • Vertebrae (most commonly lumbar)
  • Pelvis
  • Metaphysis of long bones (femur, tibia, and humerus)
• Osteomyelitis is a rare disease nowadays due to the wide use of antibiotics
• Chronic Osteomyelitis


  • Pain is chronic/recurrent with little/no systemic symptoms
  • Bone destruction with multiple irregular cavities filled with pus and sequestra
  • New bone formation with involucrum and cloaca formation
• Vertebral osteomyelitis presents with insidious onset of backache
• Horizontal extension through Volkmann's canals


  Leading to subperiosteal abscess, small sequestra formation, and possible rupture into the skin or the n
• Rupture of subperiosteal abscess

  1. May occur into the skin → sinus discharging pus & small sequestra

  2. May occur into the nearby joint → septic arthritis
• Vertical extension through medullary cavity


  Thrombosis of main nutrient vessels → sequestrum in the shaft
• Sequestrum

  Avascular, smooth, white, devoid from periosteum
• Blood tests

  1. CBC: Leukocytosis in acute OM, Normal WBC count in chronic OM, Anemia can also be present in chronic OM

  2. Inflammatory markers: ESR and C-RP ↑ in both acute & chronic OM, Blood cultures - positive in only 50% of cases
• Imaging

  1. MRI: Sensitive and most specific, Gold standard imaging modality, Important to identify site, extension, bone marrow, and soft tissue changes, T2 → hyperintense lesion (intraosseous/Brodie’s abscess), T1 → hypointense signals

  2. X-ray: Normal early course, Early changes: soft tissue swelling and loss of normal fat planes, Late findings: Codman’s triangle, Periosteal thickening, Lytic lesion with sclerosis, Presence of sequestrum, involucrum, and cloaca in chronic OM

  3. CT scan: Sequestra and involucra as well as in surgical planning

  4. Bone scan: Shows increased focal uptake after 24 to 48 hours of disease onset
• Treatment

  1. Supportive measures

  2. Nonoperative management

  3. Operative Treatment

  4. Surgical drainage
• Nonoperative management

  Take bone biopsy/blood samples, Start empiric IV/oral antibiotic therapy based on gram stain results, Switch to organism-specific antibiotics according to results of bone/blood cultures and sensitivity, Antibiotics should be continued for 4 to 6 weeks, Check C-RP every 2 to 3 days to evaluate response to treatment
• Operative Treatment

  Irrigation and debridement followed by organism-specific antibiotics, Indications: Stage III and IV osteomyelitis, Abscess formation, Draining sinus
• Surgical drainage

  Debridement, and antibiotic therapy, Indications: Deep or subperiosteal abscess, Failure to respond to antibiotics, Chronic infection
• Complications

  • Persistence or extension of infection
  • Amputation
  • Sepsis
  • Malignant transformation (Marjolin's ulcer”scc”)
  • DVT: Is an infrequent complication in children
  • Risk factors: CRP > 6, Surgical treatment, Age > 8-years-old, MRSA
  • Meningitis
  • Chronic osteomyelitis
  • Septic arthritis: Bones with intra-articular metaphysis are at risk (hip, shoulder, elbow, ankle)
  • Growth disturbances and limb-length discrepancies from growth plate involvement may result in gait abnormalities
  • Pathologic fractures
• Differential Diagnosis


  • Septic arthritis
  • Primary bone malignancy
  • Avascular bone necrosis