Bone and Soft Tissue Infections Flashcards
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
acute septic arthritis: organism
staph a
haemophilus influenzae
strep pyogenes
e. coli
acute septic arthritis: pathophysiology
acute synovitis with purulent joint effusion
articular cartilage attacked by bacterial toxin and cellular enzyme
complete destruction of the articular cartilage
acute septic arthritis: sequelae
complete recovery
partial loss of the articular cartilage and subsequent OA
fibrous or bony ankylosis
acute septic arthritis: symptoms neonate
picture of septicaemia - irritability, resistant to movement, ill
acute septic arthritis: child/adult symptoms
acute pain in single large joint
reluctant to move the joint
increased temp and pulse
increased tenderness
acute septic arthritis: investigations
FBC, WBC, ESR, CRP, blood cultures
xray
USS
aspiration
acute septic arthritis: DDx
acute osteomyelitis trauma irritable joint haemophilia rheumatic fever gout gaucher's disease
acute septic arthritis: treatment
general supportive measures
antibiotics 3-4 wks
surgical drainage and lavage
infected joint replacements
joint TB: classification
extra-articular - epiphyseal/bones with haemodynamic marrow)
intra-articular (large joints)
vertebral body
joint TB: clinical features
insidious onset and general health ill health contact with TB pain (night), swelling, loss of weight low grade pyrexia joint swelling decrease ROM ankylosis deformity
joint TB: pathology
primary complex in the lung or gut
secondary spread
tuberculous granuloma
joint TB: what may spinal present like?
little pain
present with abscess or kyphosis
joint TB: diagnosis
long Hx involvement of signle joint marked thickening of the synovium marked muscle wasting periarticular osteoporosis
joint TB: investigation
FBC, ESR mantoux test sputum/urine culture X-ray joint aspiration and biopsy
joint TB: DDx
transient synovitis monoarticular RA haemorrhagic arthritis pyogenic arthritis tumour
joint TB: treatment
- Rifampicin, isoniazid, ethambutol, pyrazinamide – 8 weeks
- Rifampicin and isoniazid – 6-12 months
- Rest and splintage
- Operative drainage rarely necessary
