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It is infectious inflammation of the bone.


Acute osteomyelitis is almost invariably a disease of children. In adults it may be because of immunosuppression caused by debility, disease or drugs eg, diabetes, malnutrition, drug addition, leukemia, or immunosuppressive therapy.


Types of osteomyelitis:

  1. Acute
  2. Sub-Acute
  3. Chronic

Acute osteomyelitis could be

  1. Primary hematogenous (Commonest)
  2. Secondary can be caused by direct exposure of bone to external environment by trauma (open fracture or surgical exposure).
  1. Etiology
    1. Staphylococcus aureus is by far the most common organism in all age groups
    2. Group B streptococcus, infecting organism in infants.
    3. Salmonella is most common organism in Sickle Cell Anemia.
    4. Pseudomonas is most common organism in I/V drug abusers.
    5. In Splenectomized patients and hypogammaglobulinemia causative organisms are H influenza, Streptococcus pneumoniae and Neisseria.

Extra Edges

  1. Animal bite - Pasteurella multiocida
  2. Human bite - Eikenella corrodens
  3. Diabetic ulcer & Fight bites - Anaerobes
  4. lmmuno compromized (HIV) – Staphylococcus aureus.
  1. Pathology
    1. Most common mode of infection is hematogenous
    2. In children metaphysis of long bone (usually lower end femur> upper end tibia) is earliest and most commonly involved site.
    3. The cause of involvement of metaphysis is because of stasis of blood - hair pin arrangement of blood vessels, deficiency in reticuloendothelial cells at metaphysis, high vascularity at metaphysis and predisposition to trauma.
      Description: osteo1
    4. The pathological sequence is inflammation, suppuration, necrosis, reactive new bone formation & ultimately resolution & healing.
    5. In infants infection spreads through physis into epiphysis (due to common blood supply) and thence into the joint. In older children physis acts a barrier to direct spread but where the metaphysis is partly intracapsular (eg hip, shoulder, elbow), pus may discharge through periosteum into joint. In adults spread is with in medullary cavity
    6. In children less than 2 year of age cortex is thin, pus bursts out from the cortex and forms a subperiosteal abscess and diaphyseal involvement is rare.
    7. In children more than 2 year of age cortex is thick hence pus travels along the medullary canal and diaphyseal involvement is common.
    8. In adults commonest site of infection is thoracolumbar spine.
    9. Vertebra infections may spread through the end plate & intervertebral disc into abutting vertebral body.
    10. Due to necrosis pieces of dead bone separate as sequestra varying in size from spicule to large segment. It is lighter than live bone and normal pattern of bone is lost. It acts as nidus and is most common cause of non-healing sinus in chronic osteomyelitis.
    11. Involucrum is dense sclerotic new bone surrounding the sequestrum
    12. If infection persists, pus & tiny sequestrated spicules of bone may continue to discharge through perforations (cloacae) in the involucrum and by sinuses to the skin surface.
  2. Clinical Feature & Investigation
    1. Pseudo paralysis
    2. Fever, high grade may be associated with chills and rigors.
    3. Locally cellulitic changes in the skin (raised temp, redness, induration)
    4. Tenderness over the involved bone.
    5. Fluctuation if abscess has burst out of bone
    6. Cellulitis in kids have to be treated like osteomyelitis until proved otherwise.
  1. Lab investigation:
    1. TLC, may be raised or normal
    2. ESR: Peak elevation occurs in 3-5 days, returns to normal 3 weeks after treatment has begun.
    3. CRP: Most reliable noninvasive Investigation. Raises within 6 hrs of infections, peaks in 2 days and returns to normal in 1 week after adequate treatment is started.
  2. Local Aspiration.
    1. Fluctuant swelling in the metaphyseal region suggestive of subperiosteal abscess, can be aspirated and can give good yield of organism.
    2. Thick needle can be put into the metaphyseal region of bone for aspiration of pus
  3. Blood Culture
    1. Positive in approx 50% of patients.
    2. Ideally blood culture should always be sent in children with hematogenous osteomyelitis, before starting patients on IV antibiotics.

Description: images-1     

X-ray Acute osteomolitis Early & late change

  1. Radiographs:
    1. Does not reveal anything till 2 weeks.
    2. 30-50% matrix must be lost to show lysis on bone.
    3. 90% abnormal at 3-4 weeks
  2. Ultrasonogram
    1. Can reveal subperiosteal collection.
    2. Can be used for US Guided aspiration.
    3. More helpful in Septic Arthritis.
  3. Bone Scan:
    Three most commonly used radioisotopes
    1. Technetium – 99m phosphate (most commonly used)
    2. Gallium – 67 citrate
    3. Indium – 111 labeled leukocytes, differentiates osteomyelitis from reactive bone formation.

Three phases of bone scan:

  1. Flow phase: similar to radionuclide angiogram in that it shows blood flow.
  2. Equilibrium phase: Blood pool image shows relative vascular flow and distribution of radioisotope into extracellular space.
  3. Delayed phase: obtained 2-4 hrs after infection when renal excretion has eliminated most of isotope except that taken by osteoblastic.
  4. Delayed phase shows osteoblastic activity and is positive in:
    1. Osteomyelitis
    2. Tumors
    3. Degenerative joint disease
    4. Trauma




















  1. MRI
    • In case of high suspicion osteomyelitis, but x- rays don’t reveal anything.
    • Can reveal bone oedema, intraosseous collection.
    • More helpful in septic arthritis

MRI is the most sensitive and specific investigation for diagnosis.



  1. Drill holes, rarely window formation for drainage of pus.
  2. Sensitive I V antibiotics for 6 weeks.
  3. Monitor disease activity with ESR AND CRP.

Treatment is started with IV antibiotics until condition begins to improve or CRP values return to normal, usually 1 or 2 weeks. There after antibiotics are given orally for another 3- 6 weeks.



  1. Chronic osteomyelitis.
  2. Acute pyogenic arthritis.
  3. Pathological fracture
  4. Growth disturbances.

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