Bone and Soft Tissue Infection Flashcards
2 types of osteomyelitis
-Primary
-Secondary
(acute + chronic)
Who’s likely to get acute osteomyelitis
- Mostly children
- Boys>girls
- Hx of minor trauma
Source of infection in osteomyelitis
- Haematogenous spread (children + elderly)
- Local spread from contiguous site of infection (surgery/open fracture/joint replacement)
Common sources of infection in:
- Infants
- Children
- Adults
- Infants = Infected umbilical cord
- Children = Tonsilitis, skin abrasions and boils
- Adults = UTI, Arterial line
Common organism causing acute osteomyelitis
Staph aureus
Organism causing acute osteomyelitis in sickle cell disease
Salmonella spp
Pathology of acute osteomyelitis
- Starts at metaphysis
- Vascular stasis (venous congestion + arterial thrombosis)
- Acute inflammation - increased pressure
- Suppuration
- Necrosis of bone (sequestrum)
- New bone formation (involucrum)
- Resolution or chronic osteomyelitis
Describe acute osteomyelitis in long bones
Starts in metaphysis
- Distal femur
- Proximal tibia
- Proximal humerus
Clinical features of acute osteomyelitis in infants
- May be very ill or appear well
- Failure to thrive
- Poss. drowsy or irritable
- Metaphyseal tenderness + swelling
- Decrease ROM
Clinical features of acute osteomyelitis in children
- Severe pain
- Reluctant to move/not weigh bearing
- Maybe be tender fever (swinging pyrexia) + tachycardia
- Malaise (fatigue, nausea, vomiting)
- Toxaemia
Clinical features of primary acute osteomyelitis in adults
- Seen commonly in thoracolumbar spine
- Backache
- Hx of UTI or urological procedure
- Elderly, diabetic, immunocompromised
Clinical features of secondary acute osteomyelitis in adults
- Secondary much more common that primary
- Often after open fracture, surgery (esp. Open Reduction External Fixation ORIF)
- Mixture of organisms
How to diagnose acute osteomyelitis
- Hx + examination (HR + temp.)
- FBC + diff WBC
- ESR, CRP
- Blood cultures x 3 (at peak temp.)
- U&Es
- X-ray (normal in the first 10-14 days)
- Ultrasound
- Aspiration
- Isotope bone scan
- MRI
Acute osteomyelitis diff diagnosis
Common -Acute septic arthritis -Trauma (fracture, dislocation) -Acute inflammatory arthritis -Transient synovitis -Soft tissue infection Rare -Sick cell crisis -Gaucher's disease -Rheumatic fever -Haemophilia
What is seen on a X-ray in acute osteomyelitis
Increasing Metaphyseal destruction
Treatment of acute osteomyelitis
- Supportive pain + dehydration
- Rest + splintage
- Antibiotics
Describe the antibiotic treatment of acute osteomyelitis
-IV or Oral
-4-6 week duration (depends on response, ESR)
-Empirical while waiting
Must consider
-Spectrum of activity
-Penetration to bone
-Safety for long term administration
Empirical antibiotics for acute osteomyelitis
Flucloxacillin + Benzylpenicillin
Complications of osteomyelitis
- Septicaemia/death
- Metastatic infection
- Septic arthritis
- Pathological fracture
- Chronic osteomyelitis
- Altered bone growth
Clinical features of subacute osteomyelitis
- Long Hx (weeks/months)
- Pain/Limp
- Local swelling/warmth occasionally
- Tenderness
DDx for subacute osteomyelitis
- Tumour (Ewing’s sarcoma, osteoid osteoma)
- TB
Presentation of Brodie’s abscess and a DDx
- Subacute osteomyelitis
- Older children
- Painful limp, no systemic features
- DDx = Ewing’s sarcoma
What’s shown on a X-ray of Brodie’s abscess
Radiographic lucency in long bone metaphysis
Treatment of Brodie’s abscess
Curettage
Investigations for subacute osteomyelitis
- X-ray
- Bone scan
- Biopsy (50% +ve) grow organism
Treatment of subacute osteomyelitis
- Prolonged course of antibiotic
- Curettage
Cause of chronic osteomyelitis
-May follow acute osteomyelitis May start de novo -Following surgery -Immunocompromised, diabetics, elderly, drug abusers -Usually staph aureus or e. coli
Treatment of chronic osteomyelitis
- Long-term antibiotics (local or systemic)
- Eradicate bone infection surgically (multiple operations)
- Amputation?
- Massive reconstruction?
What local and systemic antibiotics are used to treat osteomyelitis
- Local = Gentamicin cement/beads or collatamp (fully re-absorbable, gentamicin-impregnated collagen “sponge”
- Systemic = Oral/IV/home AB
Chronic osteomyelitis complications
- Chronically discharging sinus + flare-ups
- Ongoing (metastatic) infection (abscesses)
- Growth disturbance + deformities
- Pathological fracture
- Squamous cell carcinoma
