11: Bone and Joint Infection - Osteomyelitis/Septic Arthritis Flashcards
what diseases in adults are associated with acute osteomyelitis?
- diabetes
- rheumatoid arthritis
- immune compromise
- steroid treatment
- sickle cell disease
in what ways can acute osteomyelitis spread?
- haematogenous spread - children and elderly
- local spread from contigous site of infection: trauma (open fracture), bone surgery (ORIF), joint replacement
- secondary to vascular insufficiency
give examples of different sources of acute osteomyelitis infection in infants and children
infants: infected umbilical cord
children:
- boils
- tonsilitis
- skin abrasions
give examples of different sources of acute osteomyelitis infection in adults
UTI
arterial line
chest
gall bladder
what is the most common infecting organism in acute osteomyelitis?
staph aureus
what are the 3 most common causative organisms of acute osteomyelitis in infants < 1 year old?
- staph aureus
- group B streptococci
- e.coli
what are the 3 most common causative organisms of acute osteomyelitis in older children?
- staph aureus
- strep pyogenes
- haemophilus influenza
what are the most common causative organisms of acute osteomyelitis in adults?
- staph aureus
- mycobacterium tuberculosis
- pseudomonas aeroginosa (esp. secondary to penetrating foot injuries, IVDAs)
- coagulase negative staphylococci (prostheses)
- rarer organisms in specific occupation related injury
what is the common causative organisms in acute osteomyelitis secondary to sickle cell disease?
salmonella
what are the most common long bones that become infected during acute osteomyelitis?
metaphysis (regions where growth occurs) of:
- distal femur
- proximal tibia
- proximal humerous
which joints are most commonly affected in acute osteomyelitis?
joints with intra-articular metaphysis (regions where growth occurs):
- hip
- elbow (radial head)
outline the steps of acute osteomyelitis pathology
- starts at metaphysis - role of trauma?
- vascular stasis (venous congestion + arterial thrombosis)
- acute inflammation and increased pressure
- suppuration (pus accumulation)
- release of pressure (pus) in either: medulla, sub-periosteal or into joint
- resolution or chronic osteomyelitis
- necrosis of bone (sequestrum)
- new bone formation (involucrum)
clinical features of acute osteomyelitis in an infant
- may be minimal signs, or may be very ill
- FTT
- poss. drowsy or irritable, not feeding
- pseudoparalysis
- metaphyseal tenderness + swelling
- decrease ROM
- positional change
- commonest around the knee
- often multiple sites
clinical features of acute osteomyelitis in a child
- severe pain
- reluctant to move: neighbouring joints held flexes, not weight-bearing, may be tender.
- fever (swinging pyrexia) + tachycardia#
- malaise (fatigue, nausea, vomiting, fretful)
- toxaemia
clinical features of acute osteomyelitis in an adult
consider features of both primary OM and secondary OM
primary OM:
- most commonly seen in thoracolumbar spine
- backache: unremitting and at rest
- history of UTI or urological procedure
- elderly, diabetic, immunocompromised
secondary OM:
- much more commom
- often after open fracture, surgery (esp. ORIF)
- micxture of organisms involved
acute osteomyelitis investigations
- history and exam
- FBC, WBC, ESR, CRP
- blood cultures x 3 (at peak of temperature - 60% +ve)
- U&Es
- x-ray (normal in first 10-14 days)
- US (for sub-periosteal collection)
- aspiration/bone biopsy
- isotope bone scan (Tc-99, Gallium-67)
- labelled white cell scan (Indium-111)
- MRI
chronic osteomyelitis pathology
- cavities, possible sinus(es)
- dead bone (retained sequestra)
- involucrum
- histological picture is one of chronic inflammation
septic arthritis common organisms
- staph aureus
- haemophilus influenzae
- streptococcus pyogenes
- e.coli
