Bone and soft tissue infection Flashcards
Risk factors for acute osteomyelitis
child, boys, history of minor trauma
other illnesses eg DM, sickle cell, rheum arthritis, long term steroid use or immune compromise
3 sources of infection in acute osteomyelitis
haematogenous spread
local spread from contagious site of infection
secondary to vascular insufficiency
what 2 age groups does haematogenous spread of osteomyelitis occur?
child and elderly
3 examples of local spread from contagious site of infection in acute osteomyelitis
trauma - open fracture
bone surgery - ORIF
joint replacement
examples in different age groups of source of infection in acute osteomyelitis
a) infants
b) children
c) adults
a - infected umbilical cord
b - boils, tonsillitis, skin abrasions
c - UTI, arterial line
Main organism of acute osteomyelitis
staph aureus
exceptions to causative organisms
mycobacterium tuberculosis pseudomonas aeruginosa - IVDA coagulase -ve strep: prostheses diabetic foot - mixed and anaerobes sickle cell - salmonella mycobacterium marinum - fisherman candida - HIV
3 examples of places where long bone metaphysis are involved in acute osteomyelitis
distal femur
proximal tibia
proximal humerus
2 examples of places where joints with intra-articular metaphysis are involved in acute osteomyelitis
hip
elbow - radial head
briefly describe the pathology of acute osteomyelitis
starts at metaphysis and vascular stasis occurs.
acute inflammation, pressure build up and pus formation
release of pressure, bone dies, new bone formation and resolution or chronic osteomyelitis
suppuration
pus formation
sequestrum
necrosis of bone
involucrum
new bone formation
clinical features of acute osteomyelitis in an infant
minimal or very ill
drowsy, irritable, malaise, fail to thrive
positional change, decrease ROM, metaphyseal tender and swelling
where is the most common place for acute osteomyelitis in an infant?
knee
clinical features of acute osteomyelitis in a child
severe pain - toxaemia - reluctant to move
tender fever - tachycardia - malaise - not weight bearing
clinical features of acute osteomyelitis in an adult
backache - UTI - elderly - DM - immunocompromised
most common site for primary acute OM in an adult
thoracolumbar spine
primary or secondary acute om more common?
secondary
when does secondary acute om occur?
after open fracture, surgery, especially ORIF
5 parts of diagnosing acute OM
history and exam - pulse and temp
FBC and diff WCC - neutrophil leucocytosis
ESR, CRP
blood cultures x3 done at peak temp - 60% +ve
U+E’s - ill, dehydrated
differential diagnosis for acute OM
acute septic arthritis acute inflammatory arthritis trauma transient synovitis rare eg haemophilia soft tissue infection
6 investigations for acute OM
x-ray MRI USS aspiration isotope bone scan - TC-99, gallium-67 labelled WCC scan - indium - 111
4 microbiological diagnosis of acute om
blood cultures - haematogenous OM and septic arth.
bone biopsy
tissue or swabs of up to 5 sites around implant
debridement in prosthetic infections
why may sinus tract and superficial swabs be misleading?
contamination
treatment for acute om
supportive
antibiotics
rest and splintage
Why may antibiotics “fail”?
resistance - bacterial persistence - poor host defences
poor drug absorption - drug inactivation by host flora
poor tissue penetration - MRSA
4 indications for surgery in acute om
aspirate pus for diagnosis and culture
abscess drainage
debridement of dead/infected/contaminated tissue
refractory to non op treatment for 24-48hrs
6 complications of acute om
septicaemia/death- metastatic infection - pathological fracture - septic arthritis - altered bone growth - chronic OM
organisms in chronic om
same each flare up but often mixed
staph aureus, E.coli, strep pyogenes, proteus
pathology of chronic om
cavities, sinuses, involucrum, dead bone
list some complications of chronic om
chronically discharging sinus and flare ups
ongoing metastatic infection and abscesses
pathological fracture
growth disturbance and deformities
SSC
treatment for chronic om
long term antibiotics - local or systemic
eradicate bone infection surgically
treat soft tissue problems
deformity correction, reconstruction and amputation?
3 routes of infection for septic arthritis
haematogenous
eruption of bone abscess
direct invasion eg arthroscopy
4 main organisms causing acute septic arthritis
staph aureus - H. influenzae - strep pyogenes - E.coli
3 pathological steps of acute septic arthritis
acute synovitis with purulent joint effusion
articular cartilage attacked by bacterial toxin and cellular enzyme
complete destruction of articular cartilage
3 possible outcomes of acute septic arthritis
complete recovery
partial loss of articular cartilage and subsequent OA
fibrous or bony ankylosis
neonate acute septic arthritis presentation
septicaemia picture - ill, irritable, resistance to movement
child/adult acute septic arthritis presentation
acute pain in single large joint
- reluctant to move
- increase temp and pulse
- tenderness
adult acute septic arthritis presentation
often involves superficial joint eg wrist, knee, ankle
rare in healthy adult
investigation of acute septic arthritis
FBC, WCC, ESR, CRP, blood cultures
x-ray, USS, aspiration
most common cause of acute septic arthritis in an adult
infected joint replacement
differential diagnosis for acute septic arthritis
acute OM, irritable joint, haemophilia, rheumatic fever
trauma,gout
treatment for acute septic arthritis
general supportive measures - antibiotics - surgical drainage and lavage - emergency and infected joint replacement
3 classifications of TB bone and joint
extra articular
intra articular
vertebral body
what fraction of patients have multiple lesions in TB bone and joint
1/3
clinical features of TB bone and joint
insidious onset and general ill health TB contact pain at night, swelling, weight loss low grade pyrexia joint swelling decrease ROM ankylosis deformity
pathology of TB bone and joint
primary in lung or gut
secondary spread
TB gramuloma
role of nutrition and disease
presentation of spinal TB bone and joint
little pain with abscess or kyphosis
history diagnosis of TB bone and joint (5)
long history single joint muscle wasting marked thickening of synovium periarticular osteoporosis
investigation of TB bone and joint
FBC, ESR Mantoux test sputum/urine culture x-ray joint aspiration and biopsy
3 things to look for in x-ray for TB bone and joint
soft tissue swelling
periarticular osteopenia
articular space narrowing
2 things to look for in TB bone and joint aspiration and biopsy
AAFB
differential diagnosis for TB bone and joint
transient synovitis monoarticular RA tumour haemorrhagic arthritis pyogenic arthritis
treatment of TB bone and joint
chemotherapy - RIPE
rest and splintage, operation rare