Bone and Joint Infection Flashcards
Calor
Heat
Dolor
Pain
Tumor
Swelling
Functio laesa
Loss of function
Sequestrum
When dead bone becomes detattched from healthy bone
Gold Standard test for osteomyelitis?
Bone culture
X-ray signs of osteomyelitis
Patchy osteopenia and signs of bone destruction
Why should you give special consideration to osteomyelitis of vertebral bodies?
It can lead to permanent neurological defects
Neurologic deficits are late findings secondary to vertebral body collapse or epidural abscess. MRI is the best imaging study for osteomyelitis
What is diskitis
diskitis is an infection in the intervertebral disc space that affects different age groups, but usually spontaneously affects children under 8 years of age
What is an involucrum?
An involucrum is a complication of osteomyelitis and represents a thick sheath of periosteal new bone surrounding a sequestrum
Useful blood tests in osteomyelitis?
CRP and plasma viscosity
blood cultures, white cell count and ESR are occasionally useful
Causes of osteomyelitis
In most instances, osteomyelitis results from haematogeneous spread, although direct extension from trauma and/or ulcers is also relatively common (especially in the feet of diabetic patients).
Location of osteomyelitis
neonates: metaphysis and/or epiphysis
children: metaphysis
adults: epiphyses and subchondral regions
Organisms usually causing osteomyselitis
Staph aureus
Haemophilus in children
Causes of acute osteomyelitis
Staph aureus
Haemophilus in children
Tests used if chronic osteomyelitis is suspected?
X-ray and MRI
Involucrum
An involucrum is a complication of osteomyelitis and represents a thick sheath of periosteal new bone surrounding a sequestrum.
Often seen in chronic osteomyelitis
How does septic arthritis arise?
From inoculation
From metaphyseal spread
Direct haematogenous
Treatment for cellulitis
Best guess antibiotics to cover staph and strep
Lecturer used flucloxacillin and benzylpenicillin
Tests used if you suspect an infected arthroplasty
CRP
Joint aspiration
Bone scan (Technetium 99)
X ray
Prophylaxis for osteomyelitis surgery/ bone surgery to prevent osteomyelitis
Easily measureable:
- Clean air theatres
- Local antibiotics
- Systemic antibiotics
- Duration of surgery
Not easily measurable:
- Neat surgery
- Quality of hand washing
- Theatre discipline
Clinical features of infection
Pain Swelling Heat Tenderness Resistance to active or passive movement
Diagnosis of infection
Raised temperature
Raised white cell count
Raised CRP
Complications of infection (cartilage and …)
- Destruction of articular cartilage, leading to pain and stiffness
- Bone or fibrous ankylosis
Prophylaxis for orthopaedic surgery
Laminar flow
24 hours antibiotics starting with induction
Antibiotics in cement
Co-amoxiclav
Flucloxacillin + gentamicin
Clindamycin
Co-trimoxazole
Antibiotics used as prophylaxis for orthopaedic surgery
Co-amoxiclav
Flucloxacillin + gentamicin
Clindamycin
Co-trimoxazole
CFGCC antibiotic prophylaxis for orthopaedic surgery
- Co-amoxiclav
- Flucloxacillin & gentamycin
- Clindamycin
- Co-trimoxazole
Which ‘bugs’ do you need to provide prohpylaxis for in orthopaedic surgery?
Staphylococcus aureus Staphylococcus epidermidis (coagulase negative staphylococcus)
SA causing TKR/THR infection
96% sensitive to current prophylaxis
CNS causing THR/TKR infection
72% resistant to Flucloxacillin
40% resistant to Gentamicin
32% resistant to entire prophylactic regime
Current strategy tailored towards least problematic bug
Organisms that cause early post operative infection?
Staph aureus
Streptococcus
Enterococcus
Organisms that cause delayed (low grade) infection
3-24 months
Coagulase negative staphylococci
P. acnes
Organisms that cause late infection (>24 months)
Staph. aureus
E. coli
SIRS
systemic inflammatory response syndrome
SIRS: two or more of:
Temperature >38ºC or 90 beats/min
Respiratory rate >20 breaths/min or PaCO2 12,000 cells/mm3 or <4,000 cells/mm3
Chronic infection, SIRS and antibiotics?
SIRS is usually absent in chronic infections, if it is absent then there is no need for immediate antibiotics
Bacteria usually responsible for acute and chronic infections
Acute primary infections
S. aureus
Streptococcus spp
Chronic infections
CoNS
Propionibacteria
Why can CRP be confusing in bone and joint infection?
Not always elevated, especially in chronic infections
Influenced by underlying disease and acute stress (surgery)
Only useful in monitoring cases without major surgery
Sign standards for surgery prophylaxis antibiotics
The first dose must be given within 30 minutes of the start of surgery
Prophylaxis should not continue >24h after surgery
What do you do if there is MRSA pre-op when you screen for it?
Decolonise if positive
