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  2. 2. Osteomyelitis Osteomyelitis is defined as an inflammation of the bone caused by an infecting organism Mostly bacterial, can be fungal
  3. 3. Osteomyelitis The infection may be limited to a single portion of the bone or may involve the marrow, cortex, periosteum, and the surrounding soft tissue The infection generally is due to a single organism, but polymicrobial infections can occur, especially in diabetic foot
  4. 4. CLASSIFICATION Duration of symptoms Acute < 2 weeks Subacute 2-3 weeks Chronic > 3 weeks  Mechanism of infection exogenous or hematogenous Based on the host response to the disease pyogenic or nonpyogenic
  5. 5. ACUTE HEMATOGENOUS OSTEOMYELITIS Acute hematogenous osteomyelitis is the most common type of bone infection and is usually is seen in children Staph aureus is the common organism
  6. 6. The causes of bacteremia Localized trauma Chronic illness Malnutrition Inadequate immune system In many cases, the exact cause of the disease cannot be identified
  7. 7. Pathology In children, the infection generally involves the metaphyses of rapidly growing long bones
  8. 8. Why metaphysis is infected? Vascular loops present in the long bone metaphysis that take sharp bends and empty into venous lakes, create areas of turbulence where bacteria accumulate and could cause infection
  9. 9. Why metaphysis is infected? Relative absence of macrophages in metaphyseal bone Gaps in the endothelium of growing metaphyseal vessels allow passage of bacteria that may adhere to type I collagen in the hypertrophic zone of the physis S.aureus surface antigens may play a key role in this local adherence Micro haematoma due to trauma is common in metaphysis
  10. 10. Pathology Bacterial seeding Inflammatory reaction, which can cause local ischemic necrosis of bone and subsequent abscess formation Intramedullary pressure increases Purulent material escape through the cortex into the subperiosteal space Subperiosteal abscess then develops Periosteum is lifted away from bone Ischaemia of bone Extensive sequestra formation and chronic osteomyelitis
  11. 11. Pathology
  12. 12. Pathology The age distribution of acute hematogenous osteomyelitis in children is bimodal Children younger than 2 years Children 8 to 12 years old In children younger than 2 years, some blood vessels cross the physis and may allow the spread of infection into the epiphysis
  13. 13. Pathology In children older than 2 years, the physis effectively acts as a barrier to the spread of a metaphyseal abscess Because the metaphyseal cortex in older children is thicker, the diaphysis is at greater risk in these patients If the infection spreads into the diaphysis, the endosteal blood supply may be jeopardized With a concurrent subperiosteal abscess, the periosteal blood supply is damaged and can result in extensive sequestration and chronic osteomyelitis if not properly treated
  14. 14. Causative Organisms S. aureus Group B streptococcus Gram negative coliforms Haemophilus influenzae infections occur primarily in children 6 months to 4 years old
  15. 15. Symptoms General – fever, sweating, chills and rigors, patient is usually in shock Local – local swelling, limitation of movement
  16. 16. Signs General – increased temperature, increased pulse rate, signs of dehydration and shock Local – tenderness, local erythema, raised temperature, decreased movements, fluctuation (20%) and effusion (10%) may be present
  17. 17. Diagnosis Evaluation of Acute Hematogenous Osteomyelitis    History and physical examination  Laboratory tests:  White blood cell count  Erythrocyte sedimentation rate  C-reactive protein  Plain radiograph    Technetium-99m bone scan  MRI   Aspiration for suspected abscess
  18. 18. X-rays < 48 hours Few changes Rarefaction is the earliest sign Loss of demarcation of line between subcutaneous shadows and muscles Appearance of transverse lines of increased densities outward from the muscles >2 weeks Periosteal new bone formation is seen Rarefaction
  19. 19.  Osteomyelitis of the tibia in a young child. Numerous abscesses in the bone show as radiolucency.
  20. 20. General supportive care Intravenous fluids Appropriate analgesics Comfortable positioning of the affected limb Frequent serial examinations should be done
  21. 21. Treatment Empirical antibiotic coverage for the most likely infecting organism should be started if Gram stain is negative, and the patient should be carefully monitored The C-reactive protein should be checked every 2 to 3 days after the initiation of antibiotic therapy If no appreciable clinical response to antibiotic treatment is noted within 24 to 48 hours, occult abscesses must be sought, and surgical drainage should be considered
  22. 22. Treatment If an abscess requiring surgical drainage is found by subperiosteal or bone marrow aspirate, surgical drainage and intravenous antibiotics based on the Gram stain should be started
  23. 23. Treatment The two main indications for surgery in acute hematogenous osteomyelitis are (1) the presence of an abscess requiring drainage (2) failure of the patient to improve despite appropriate intravenous antibiotic treatment
  24. 24. Surgery The objective of surgery is to drain any abscess cavity and remove all nonviable or necrotic tissue  When a subperiosteal abscess is found in an infant, several small holes should be drilled through the cortex into the medullary canal If intramedullary pus is found, a small window of bone is removed The skin is closed loosely over drains, and the limb is splinted  The limb is protected for several weeks to prevent pathological fracture
  25. 25. Complications Septicemia and pyemia Septic arthritis Chronic osteomyelitis Pathological fractures Growth disturbances
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