Bone and Joint Infections

Two main forms:
1. Haematogenous: results from an infection carried in the blood stream
2. Exogenous (Non – haematogenous): spread from nearby infections, open fractures and surgical procedures.

Haematogenous Osteomyelitis

1. Bone is seeded with bacteria from a distant site of infection.
2. Common sources: Throat, teeth, skin, urinary tract, gastrointestinal tract, lungs Metaphyses of long bones commonly involved
3. Most common pathogen is Staphylococcus aureus
4. Gram negative seedlings come from GIT and GUT infections (usually secondary to instrumentation)
5. Common in children ( immunity, trauma, other infections)
6. Second peak seen 50 – 70 years.

Pathogenesis of acute haematogenous Osteomyelitis(AHO)

• Terminal branches of the metaphyseal arteries form loops and enter venous sinusoids which are larger and irregular. Therefore flow becomes sluggish and bacteria can settle in this area and cause infection.
• Rapid duplication gives rise to an abscess just beneath the growth plate, extends along the Volkmann canals to the sub periosteal region and elevates the thick periosteum Ruptures and extends to the subcutaneous tissue, and through the skin
• Lifting of periosteum leads to an avascular area of cortical bone  sequestrum, this act like a nidus for continuing infection.
• Antibiotics won’t reach the sequestrum because it is avascular therefore impossible to treat AOM with antibiotics alone
• Elevated periosteum lays down new bone  Involucrum
• The epiphyseal plate prevent infection spreading into the adjacent joint
• Sometimes the body defences can wall off the infection to a small abscess area. This is a Brodie’s abscess.
• Early and aggressive treatment can stop this bone destruction.
• So prompt diagnosis and treatment is essential to prevent a chronic condition.

Clinical manifestation

1. Fever, chills, malaise, localized pain
2. Point tenderness found 1-2 cm below the joint line.
3. Child will refuse to walk
4. Keeps the knee flexed.
5. Area feels warm; a tender soft tissue swelling is noted.
6. History of recent trauma in some patients. Infective focus may be positive

Management:

1. Do blood counts, ESR, Blood culture and ABST
2. X Rays of the area are done
3. Admit
4. Splint
5. Elevate
6. Pain relief
7. Antibiotics: Cloxacillin IV or Cloxacillin + Fucidin IV
8. If the child responds, convert into oral when oral drugs are tolerated.
9. If there is no improvement, or if the child present 4-5 days late and very ill do I and D in OT under GA.
10. If pus is not found bone is drilled to let deep pus out.
11. Antibiotics are given for 6 weeks.
12. Followed up with ESR, WBC/DC and X Rays