Complications of Sickle Cell Anaemia - Osteomyelitis

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Description

Acute or chronic bone infection affecting the metaphysis of bone. The commonest site of Osteomyelitis is usually in the lower limbs, especially the Tibia. It is important to make an early diagnosis of the acute stage of osteomyelitis to prevent serious long-term orthopaedic sequela caused by chronic osteomyelitis. It may be difficult to distinguish between acute osteomyelitis and bone infarctions caused by VOCs. A high index of suspicion from history, and thorough work -up is important.

Osteomyelitis can be classified, depending on the duration and presentation, into; Acute, post-acute, chronic. Subacute osteomyelitis should be distinguished from post- acute as this is a type of osteomyelitis that is caused by less virulent organisms.

Micro-organisms implicated in OM include Staphylococcus aureus (commonest), Salmonella typhi (common), non-Salmonella typhi spp (common), E. coli, Psuedomonas aeruginosa, Enterobacter spp, Hemophilus influenza type B, Klebsiella spp and Proteus spp

Bacteremia caused due to the gram-negative microbes is believed to result from sickling within the mesenteric vessels and subsequent gastrointestinal infarction and translocation of the GI microorganisms into the bloodstream.

Signs and Symptoms

Acute Osteomyelitis < 2weeks

Subacute Osteomyelitis 2-6 weeks

Chronic Osteomyelitis 6 weeks or more

Fever or chills

Usually caused by indolent bacteria

Pus discharge from sinus

Irritability or lethargy in young children

Uncommon infection with bone pain

Pathological fractures presenting as acute pain.

Pain around the infection

Radiographic changes without systemic symptoms

Limb Deformity

Swelling of affected limb

Characterised by a Brodie’s abscess on imaging.

Inability to bear weight on the affected limb.

Warmth and redness over the area of the infection

 

 

Loss of movement

 

 

Maybe asymptomatic

 

 

Investigations

  • Gold standard tools for the diagnosis is bone biopsy test with histopathological examination and tissue
    culture, (both aerobic and anaerobic bacteria culture)
  • FBC/DC
  • Blood cultures, pus Swab and culture
  • CRP/ESR
  • X- rays of affected limb

NOTE:

  • Xray changes in acute osteomyelitis do not appear until about 10 days after the onset of symptoms which
    coincides with the post-acute stage
  • Ultrasound/MRI in acute episodes are difficult to assess.
  • Joint aspiration for culture of septic arthritis (never aspirate an affected joint without prior consultation
    with a Senior Doctor)

Treatment

  • Acute osteomyelitis should be managed medically with antibiotics.
  • IV Cloxacillin for S. aureus OM (commonest)
  • If Gram stain shows gram-negative bacilli - add a third-generation cephalosporin,
  • Ciprofloxacin can also be used If Salmonella infection is suspected or confirmed by culture.

Recommended duration for antibiotic administration is at least 4 – 6 weeks which should include 1 – 2 weeks of intravenous administration. Followed by 2 – 4 weeks of oral.

Serial monitoring of infection markers required to monitor antibiotic therapy effectiveness

ESR is less reliable in neonates and sickle cell patients.Other Supportive management includes:

  • Hydration
  • Adequate Pain management
  • Resting affected limb

Orthopaedics consultation:

  • For post-acute and chronic osteomyelitis
  • Bone drilling if acute (to relieve the exudate and hence pressure in the medullary cavity to prevent bone necrosis; sequestrum formation) and post-acute osteomyelitis (to reduce the pressure from the accumulated pus within the medullary cavity of the bone).
  • Splintage of affected limb with Plaster of Paris (POP) or traction for pathological fractures prior to referral
  • Co-Management of patients by Medical and surgical teams is needed.