Bone and Joint Infection

Question 1

Calor

Answer 1

Heat

Question 2

Dolor

Answer 2

Pain

Question 3

Tumor

Answer 3

Swelling

Question 4

Functio laesa

Answer 4

Loss of function

Question 5

Sequestrum

Answer 5

When dead bone becomes detattched from healthy bone

Question 6

Gold Standard test for osteomyelitis?

Answer 6

Bone culture

Question 7

X-ray signs of osteomyelitis

Answer 7

Patchy osteopenia and signs of bone destruction

Question 8

Why should you give special consideration to osteomyelitis of vertebral bodies?

Answer 8

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

Question 9

What is diskitis

Answer 9

diskitis is an infection in the intervertebral disc space that affects different age groups, but usually spontaneously affects children under 8 years of age

Question 10

What is an involucrum?

Answer 10

An involucrum is a complication of osteomyelitis and represents a thick sheath of periosteal new bone surrounding a sequestrum

Question 11

Useful blood tests in osteomyelitis?

Answer 11

CRP and plasma viscosity

blood cultures, white cell count and ESR are occasionally useful

Question 12

Causes of osteomyelitis

Answer 12

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).

Question 13

Location of osteomyelitis

Answer 13

neonates: metaphysis and/or epiphysis
children: metaphysis
adults: epiphyses and subchondral regions

Question 14

Organisms usually causing osteomyselitis

Answer 14

Staph aureus

Haemophilus in children

Question 15

Causes of acute osteomyelitis

Answer 15

Staph aureus

Haemophilus in children

Question 16

Tests used if chronic osteomyelitis is suspected?

Answer 16

X-ray and MRI

Question 17

Involucrum

Answer 17

An involucrum is a complication of osteomyelitis and represents a thick sheath of periosteal new bone surrounding a sequestrum.
Often seen in chronic osteomyelitis

Question 18

How does septic arthritis arise?

Answer 18

From inoculation
From metaphyseal spread
Direct haematogenous

Question 19

Treatment for cellulitis

Answer 19

Best guess antibiotics to cover staph and strep

Lecturer used flucloxacillin and benzylpenicillin

Question 20

Tests used if you suspect an infected arthroplasty

Answer 20

CRP
Joint aspiration
Bone scan (Technetium 99)
X ray

Question 21

Prophylaxis for osteomyelitis surgery/ bone surgery to prevent osteomyelitis

Answer 21

Easily measureable:

• Clean air theatres
• Local antibiotics
• Systemic antibiotics
• Duration of surgery

Not easily measurable:

• Neat surgery
• Quality of hand washing
• Theatre discipline

Question 22

Clinical features of infection

Answer 22

Pain
Swelling
Heat
Tenderness
Resistance to active or passive movement

Question 23

Diagnosis of infection

Answer 23

Raised temperature
Raised white cell count
Raised CRP

Question 24

Complications of infection (cartilage and …)

Answer 24

• Destruction of articular cartilage, leading to pain and stiffness
• Bone or fibrous ankylosis

Question 25

Prophylaxis for orthopaedic surgery

Answer 25

Laminar flow 24 hours antibiotics starting with induction Antibiotics in cement Co-amoxiclav Flucloxacillin + gentamicin Clindamycin Co-trimoxazole

Question 26

Antibiotics used as prophylaxis for orthopaedic surgery

Answer 26

Co-amoxiclav Flucloxacillin + gentamicin Clindamycin Co-trimoxazole

Question 27

CFGCC antibiotic prophylaxis for orthopaedic surgery

Answer 27

- Co-amoxiclav - Flucloxacillin & gentamycin - Clindamycin - Co-trimoxazole

Question 28

Which 'bugs' do you need to provide prohpylaxis for in orthopaedic surgery?

Answer 28

``` 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

Question 29

Organisms that cause early post operative infection?

Answer 29

Staph aureus Streptococcus Enterococcus

Question 30

Organisms that cause delayed (low grade) infection | 3-24 months

Answer 30

Coagulase negative staphylococci | P. acnes

Question 31

Organisms that cause late infection (>24 months)

Answer 31

Staph. aureus | E. coli

Question 32

SIRS | systemic inflammatory response syndrome

Answer 32

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

Question 33

Chronic infection, SIRS and antibiotics?

Answer 33

SIRS is usually absent in chronic infections, if it is absent then there is no need for immediate antibiotics

Question 34

Bacteria usually responsible for acute and chronic infections

Answer 34

Acute primary infections S. aureus Streptococcus spp Chronic infections CoNS Propionibacteria

Question 35

Why can CRP be confusing in bone and joint infection?

Answer 35

Not always elevated, especially in chronic infections Influenced by underlying disease and acute stress (surgery) Only useful in monitoring cases without major surgery

Question 36

Sign standards for surgery prophylaxis antibiotics

Answer 36

The first dose must be given within 30 minutes of the start of surgery Prophylaxis should not continue >24h after surgery

Question 37

What do you do if there is MRSA pre-op when you screen for it?

Answer 37

Decolonise if positive