Bone and Soft Tissue Infections Flashcards
(40 cards)
who gets acute osteomyelitis?
children boys Hx of trauma diabetes RA immune compromise long term steroid treatment sickle cell
source of acute osteomyelitis infection
• Haematogenous spread – children and elderly • Local spread from contiguous site of infection o Trauma – open fracture o Bone surgery – ORIF (open reduction internal fixation) o Joint replacement • Secondary to vascular insufficiency • Infants o Infected umbilical cords • Children o Boils o Tonsillitis o Skin abrasions • Adults o UTI o Arterial line
organisms causing acute osteomyelitis: infants < 1
stap a
group B strep
e. coli
organisms causing acute osteomyelitis: older children
staph a
strep pyogenes
H. influenzae
organisms causing acute osteomyelitis: adults
staph a coagulase -ve staph (protheses) propionibacterium spp (protheses) mycobacterium tuberculosis pseudomonas aeruginosa
organisms causing acute osteomyelitis: diabetic foot and pressure sores
mixed infection inc anaerobes
organisms causing acute osteomyelitis: sickle cell
salmonella spp
organisms causing acute osteomyelitis: fishermen, filleters
mycobacterium marinum
organisms causing acute osteomyelitis: HIV/AIDS
candida
pathophysiology of acute osteomyelitis
- Starts at metaphysis
- Vascular stasis (venous congestion + arterial thrombosis)
- Acute inflammation – increased pressure
- Suppuration
- Release of pressure (medulla, sub-periosteal, into joint)
- Necrosis of bone (sequestrum)
- New bone formation (involucrum)
- Resolution – or not
clinical features of acute osteomyelitis: infant
minimal signs to very ill failure to thrive drowsy and irritably metaphyseal tenderness + swelling decrease ROM positional change comment around knee
clinical features of acute osteomyelitis: children
severe pain reluctant to move, not weight bearing may be tender fever (swinging pyrexia) and tachycardia malaise toxaemia
clinical features of acute osteomyelitis: adults
primary OM in thoracolumbar spine:
back ache
Hx of UTI or urological procedure
elderly, diabetic, immunocompromised
secondary OM:
after open fracture, ORIF
mixture of organisms
diagnosis of acute osteomyelitis
• Hx and clinical exam o Pulse and temperature • FBC + diff WBC (neutrophil leucocytosis) • ESF, CRP • Blood cultures x 3 • U+Es – ill, dehydrated • X-ray (normal first 10-14 days) o 10 – 20 days early periosteal changes o Medullary changes – lytic areas o Late osteonecrosis – sequestrum o Late periosteal new bone – involucrum • USS • Aspiration • Isotope bone scan (Tc-99, Gallium-67) • Labelled white cell scan (Indium-111) • MRI • Microbiology o Blood cultures in haematogenous osteomyelitis and septic arthritis o Bone biopsy o Tissue or swabs from up to 5 sites around implant at debridement in prosthetic infections o Sinus tract and superficial swab results may be misleading
DDx acute osteomyelitis
• Acute inflammatory arthritis • Trauma (fracture, dislocation etc) • Transient synovitis (irritable hip) • Rare o Sickle cell crisis o Gaucher’s disease o Rheumatic fever o Haemophilia • Soft tissue infection
treatment of acute osteomyelitis
• Supportive treatment for pain and dehydration
o General care, analgesia
• Rest and splintage
• Antibiotics
o Route (IV/oral switch – 7-10 days)
o Duration (4-6 weeks depending on response, ESR_
o Choice – empirical (fluclox and benxylpen) while waiting
o Spectrum of activity
o Penetration to bone
o Safety for long term administration
• Surger
indications for surgery in acute osteomyelitis
§ Aspiration of pus for diagnosis & culture
§ Abscess drainage (multiple drill-holes, primary closure to avoid sinus)
§ Debridement of dead/infected /contaminated tissue
§ Refractory to non-operative Rx >24-48 hrs.
o Timing, drainage, lavage
o Infected joint replacement – one stage revision/two stage revision/antibiotics only?
complications of acute osteomyelitis
- Septicaemia, death
- Metastatic infection
- Pathological fracture
- Septic arthritis
- Altered bone growth
- Chronic osteomyelitis
chronic osteomyelitis causes
This may follow on from acute osteomyelitis, mow much rarer in children. However, it may also occur de novo: following operation, post open fracture (possibly many years ago), immunosuppressed, diabetics, elderly, drug abusers etc. May occur as a result of repeated breakdown of “healed” wounds.
organisms causing chronic osteomyelitis
often mixed
usually same organism with each flar up
stap a, e. coli, strep pyogenes, proteus
pathology of chronic osteomyelitis
cavities, possibly sinus
dead bone (retained sequestra)
involucrum
histological picture is one of chronic inflammation
complication of chronic osteomyelitis
chronically discharging sinus + flare ups
ongoing (metastatic) infection (abscesses)
pathological fracture
growth disturbance + deformities
squamous cell carcinoma
treatment of chronic osteomyelitis
long term antibiotics (gentamicin cement/beads)
surgically eradicate bone infections (multiple operations)
treat soft tissue problems
deformity correction
massive reconstruction
amputation
acute septic arthritis: route of infection
haematogenous
eruption of bone abscess
direct invasion - penetrating wound, intra-articular injury, arthroscopy
