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
acute osteomyelitis differential diagnosis
- cellulitis
- acute septic arthritis
- trauma
- acute inflammatory arthritis
- transient synovitis (‘irritable hip’)
- rare: sickle cell disease, rheumatic fever, haemophilia etc.)
acute osteomyelitis treatment
- supportive treatment: general care, analgesia
- rest and splintage
antibiotics:
- route: IV/oral switch - 7-10 days?
- duration: 4-6 weeks depending on response, CRP/ESR
- choice: empirical (flucloxacillin + benzylpenicillin) while waiting
- selection of antibiotic when specific organism identified
- rarely surgery
what are the indications for surgery in acute osteomyelitis?
- aspiration of pus for diagnosis and culture
- abscess drainage (multiple drill-holes, primary closure to avoid sinus)
- debridement of dead/infected/contaminated tissue
- refractory to non-operative Rx > 24-48hrs
acute osteomyelitis complications
- metastatic infection
- pathological fracture
- septic arthritis
- septicaemia, death
- altered bone growth
- chronic osteomyelitis
most common organisms in chronic osteomyelitis
- often mixed infection
- mostly staph aureus, E.coli, strep.pyogenes, proteus
chronic osteomyelitis pathology
- cavities, possible sinus(es)
- dead bone (retained sequestra)
- involucrum
- histological picture is one of chronic inflammation
chronic osteomyelitis treatment
- long-term antibiotics either locally (gentamicin cement/beads/sponge) or systemic (orally/IV/home AB)
- eradicate bone infection- surgically (multiple ops)
- treat soft tissue problems
- deformity correction?
- massive reconstruction?
- amputation?
chronic osteomyelitis complications
- chronically discharging sinus + flare ups
- ongoing (metastatic) infection (abscesses)
- pathological fracture
- growth disturbance + deformities
- squamous cell carcinoma (0.07%)
septic arthritis route of infection
- haematogenous
- eruption of bone abscess
- direct invasion : penetrating wound, joint injection, intra-articular injury, arthroscopy
septic arthritis common organisms
- staph aureus
- haemophilus influenzae
- streptococcus pyogenes
- e.coli
acute septic arthritis: pathology steps
- acute synovitis with purulent joint effusion
- articular cartilage attacked by bacterial toxin and cellular enzymes
- complete destruction of the articular cartilage
- complete recovery OR
- partial loss of articular cartilage and subsequent OA OR
- fibrous or bony ankylosis
what is the presentation of acute septic arthritis in neonates?
- irritability
- resistance to joint movement
- septicaemia
what is the presentation of acute septic arthritis in child/adults?
- acute pain in single large joint
- reluctant to move the joint
- swelling (seen in superficial joint)
- NOT erythema - unless superficial and later
- increase temp and pulse
- increase tenderness
acute septic arthritis treatment
- general supportive measures
- urgent surgical drainage & lavage, emergency open or arthroscopic lavage
- appropriate Abx (3-4 weeks)
- infected joint replacements
tuberculosis clinical features
- insidious onset and general ill health
- contact with TB
- pain esp at night, swelling, loss of weight
- low grade pyrexia
- joint swelling
- decrease ROM
- ankylosis
- progressive deformity
diagnostic signs of TB joint infection
- long history
- involvement of single joint
- marked thickening of the synovium
- marked muscle wasting
- periarticular osteoporosis
tuberculosis investigations
- FBC, ESR
- Mantoux test
- sputum/urine culture
- xray: soft tissue swelling, periarticular osteopeania, articular space narrowing
- joint aspiration and biopsy
tuberculosis treatment
- rifampicin, isoniazid and ethambutol for 8 weeks
- follow on with rifampicin and isoniazid for 6-12 months
- rest and splintage
- operative drainage/fusion rarely neccesary
- antibiotics
