Bone and soft tissue infection Flashcards
What is a bone infection known as
Osteomyelitis
What is a joint infection known as
Septic Arthritis
Types of osteomyelitis
acute
chronic
specific (e.g. TB)
non-specific (most common)
What organisms mainly affect children <1
staph A, Group b strep, E.coli
What organisms mainly affect Older children (3)
Staph aureus, Strep pyogenes, Haemophilus influenzae
What organisms mainly affect adults ? (4)
Staph A
coagulase negative staphylococci Mycobacterium tuberculosis
Pseudomonas aeroginosa
Acute Osteomyelitis = can also be caused by other causes - what are they? (4)
Diabetic foot and Pressure sores - mixed infection including anaerobes
Sickle cell disease – Salmonella spp
Mycobacterium marinum (fishermen, filleters)
Candida (debilitating illness, HIV AIDS)
Acute Osteomyelitis Pathology - what long bones does it affect (3)
metaphysis
distal femur
proximal tibia
proximal humerus
Acute Osteomyelitis Pathology - what joints does it affect? (2)
with intra-articular metaphysis
hip
elbow (radial head)
Different causes of acute Osteomyelitis (8)
role of trauma? vascular stasis acute inflammation – increased pressure suppuration release of pressure (medulla, sub-periosteal, into joint) necrosis of bone (sequestrum) new bone formation (involucrum) resolution - or not (chronic osteomyelitis
Acute Osteomyelitis Clinical Features - Infant - where are features most common? (7)
may be minimal signs, or may be very ill failure to thrive poss. drowsy or irritable metaphyseal tenderness + swelling decrease ROM positional change commonest around the knee
Acute Osteomyelitis Clinical Features - Child (5)
severe pain
reluctant to move (neighbouring joints held flexed); not weight bearing
may be tender fever (swinging pyrexia) + tachycardia
malaise (fatigue, nausea, vomiting – “nae weel” - fretful
toxaemia
Acute OsteomyelitisClinical Features - Adult - where are features most common?
Primary OM seen commonly in thoracolumbar spine
backache
history of UTI or urological procedure
elderly, diabetic, immunocompromised
What type of acute OM is more common in adults? when does this often happen?
Secondary
often after open fracture, surgery (esp. ORIF)
mixture of organisms
Acute Osteomyelitis -Diagnosis (5)
history and clinical examination (pulse + temp.)
FBC + diff WBC (neutrophil leucocytosis)
ESR, CRP
blood cultures x3 (at peak of temperature – 60% +ve)
U&Es – ill, dehydrated
Acute Osteomyelitis - Differential Diagnosis
GIVE EXAMPLES (5)
soft tissue infection
cellulitis - (deep) infection of subcutaneous tissues (Gp A Strep)
erysipelas - superficial infection with red, raised plaque (Gp A Strep)
necrotising fasciitis - aggressive fascial infection (Gp A Strep, Clostridia)
gas gangrene - grossly contaminated trauma (Clostridium perfringens)
toxic shock syndrome - secondary wound colonisation (Staph aureus)
Acute Osteomyelitis Diagnosis- TESTS (6)
X-ray (normal in the first 10-14 days) ultrasound aspiration Isotope Bone Scan (Tc-99, Gallium-67) labelled white cell scan (Indium-111) MRI
When will periosteal changes show on radiograph
10-20 days
Medullary changes (radiograph) are?
- lytic areas
late osteonecrosis on radiograph is
sequestrum
late periosteal new bone on radiograph is
involucrum
Technetium scan is used in the
early and late phases
Acute Osteomyelitis - Microbiological diagnosis
blood cultures in haematogenous osteomyelitis and septic arthritis
bone biopsy
tissue or swabs from up to 5 sites around implant at debridement in prosthetic infections
sinus tract and superficial swab results may be misleading (skin contaminants
Acute Osteomyelitis - Treatment
supportive treatment for pain and dehydration – general care, analgesia
rest & splintage
Acute Osteomyelitis - Treatment - antibiotics
antibiotics
route (IV/oral switch – 7-10 days?)
duration (4-6 wks – depends on response, ESR)
choice - empirical (Fluclox + BenzylPen) while waiting
3 features antibiotics have
spectrum of activity
penetration to bone
safety for long term administration
Why may there be antibiotics failure in treatment ?
drug resistance – e.g. lactamases bacterial persistence - ‘dormant’ bacteria in dead bone poor host defences - IDDM, alcoholism… poor drug absorption drug inactivation by host flora poor tissue penetration MRSA
Acute Osteomyelitis -Treatment - Surgery
indications
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
Acute Osteomyelitis -Treatment - (3)
timing, drainage, lavage
infected joint replacements - one stage revision/ two stage revision/ antibiotics only
Acute Osteomyelitis - Complications (6)
septicemia, death metastatic infection pathological fracture septic arthritis altered bone growth chronic osteomyelitis
Chronic Osteomyelitis may follow
AOM
Chronic Osteomyelitis - when may it start? (4)
de novo
following operation
following open # (poss. many years earlier)
immunosuppressed, diabetics, elderly, drug abusers, etc.
repeated breakdown of “healed” wounds
Chronic Osteomyelitis - Organisms causing?
often mixed infection
usually same organism(s) each flare-up
mostly Staph. Aureus, E. Coli, Strep. pyogenes, Proteus
Chronic Osteomyelitis - Pathology (4)
cavities, poss. sinus(es)
dead bone (retained sequestra)
involucrum
histological picture is one of chronic inflammation
Chronic Osteomyelitis - Complications (5)
chronically discharging sinus + flare-ups
ongoing (metastatic) infection (abscesses)
pathological fracture
growth disturbance + deformities
squamous cell carcinoma (0.07%)
How do you treat Chronic osteomyelitis - antibiotics
long-term antibiotics?
local (gentamicin cement/beads, collatamp)
systemic (orally/ IV/ home AB)
How do you treat Chronic osteomyelitis - (5)
eradicate bone infection- surgically (multiple operations)
treat soft tissue problems
deformity correction?
massive reconstruction?
amputation? (how many operations/years later?
Acute Septic Arthritis- What is theRoutes of infection (3)
haematogenous eruption of bone abscess direct invasion penetrating wound (iatrogenic? – joint injection) intra-articular injury arthroscopy
Acute Septic Arthritis - the route of infection has a
metaphyseal septic focus
→ either septic arthritis
→ or osteomyelitis
Organisms causing Acute Septic Arthritis (4)
Staphylococus aureus
Haemophilus influenzae
Streptococcus pyogenes
E. coli
Acute Septic Arthritis Pathology (3)
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 (3) - what happens?
complete recovery or partial loss of the articular cartilage and subsequent OA or fibrous or bony ankylosis
Acute Septic Arthritis - Neonate - what do we always picture?
septicaemia
irritability
resistant to movement
ill
Acute Septic Arthritis Child/Adult - main features
physical features?
Acute pain in single large joint
reluctant to move the joint (any movement – c.f. bursitis where RoM OK)
increase temp. and pulse
increase tenderness
Acute Septic Arthritis in anAdult often involves what joint?
superficial joint (knee, ankle, wrist) - rare in adults and may be delayed diagnosis
Acute Septic Arthritis - Adult - investigations (5)
FBC, WBC, ESR, CRP, blood cultures
X ray
ultrasound
aspiration
Acute Septic Arthritis Adult – Infected Joint Replacement is the
most common cause of septic arthritis in adult
Acute Septic Arthritis Adult – Infected Joint Replacement- most common organism ?
Staph
rare but a disaster - can cause death
Acute Septic Arthritis- Differential Diagnosis (7)
acute osteomyelitis trauma irritable joint haemophilia rheumatic fever gout Gaucher’s disease
Acute Septic Arthritis - Treatment (surgical/antibiotics)
general supportive measures
antibiotics (3-4 weeks)
surgical drainage & lavage - emergency (“never let the sun set on pus” ); open or arthroscopic lavage;
infected joint replacements - one stage revision, two stage revision, antibiotics only?
Tuberculosis- Bone and Joint - what are the 3 different classifications?
extra-articular (epiphyseal / bones with haemodynamic marrow)
intra-articular (large joints)
vertebral body
multiple lesions
Tuberculosis - Clinical Features (8)
insidious onset & general ill health contact with TB pain (esp. at night), swelling, loss of weight low grade pyrexia joint swelling decrease ROM ankylosis deformity
TB - pathology
primary complex (in the lung or the gut)
secondary spread
tuberculous granuloma
Aids/HIV?
How does Tb spinal present?
little pain
present with abscess or kyphosis
Tuberculosis -Diagnosis (5)
long history involvement of single joint marked thickening of the synovium marked muscle wasting periarticular osteoporosis
Tuberculosis- Investigation, biopsy numbers?
FBC , ESR
Mantoux test
Sputum/ urine culture
Joint aspiration and biopsy
AAFB identified in 10-20%
culture +ve in 50% of cases
Tuberculosis- Investigation - radiography features you look for?
XRAY
soft tissue swelling
periarticular osteopaenia
articular space narrowing
Tuberculosis -Differential Diagnosis (5)
transient synovitis monoarticular RA haemorrhagic arthritis pyogenic arthritis Tumour
TuberculosisTreatment - INITIAL
chemotherapy
initial - rifampicin
isoniazid - 8 weeks
ethambutol
TuberculosisTreatment - After initial
rifampicin and isoniazid 6-12 month
rest and splintage
operative drainage rarely necessary
