6: Bone and joint infections

Question 1

Infection presents with all the cardinal features of ___, but not all ___ is infectious.

Answer 1

inflammation

Question 2

What are the cardinal features of inflammation?

Answer 2

Rubor - redness

Calor - hot

Dolor - painful

Tumor - swelling

Loss of function

Question 3

Generally, when should you start antibiotics?

What are the exceptions?

Answer 3

When you know for sure that it’s an infection - through investigation

If the patient is imminently going to die / lose stuff - sepsis, necrotising fasciitis

Question 4

How long should suspected bone and joint infection specimens be cultured for?

Answer 4

1 week

otherwise standard 48hrs

Question 5

What are some inflammatory markers analysed in blood tests?

Answer 5

CRP

PV

ESR

Question 6

What cells pick up technetium?

Answer 6

Osteoblasts

So scan indicates increased turnover, metabolic activity

Question 7

What does MRI pick up as opposed to X-ray?

Answer 7

Soft tissue swelling, fluid

Useful for seeing pus-filled abscesses in osteomyelitis

Question 8

What is osteomyelitis?

Answer 8

Infection of bone

Question 9

What is the most common means of developing acute osteomyelitis?

Answer 9

Post-trauma / open fractures

Question 10

By which means may infection get to bone in children and immunosuppressed people?

Answer 10

Haematogenous spread (via blood)

Question 11

Which bugs are usually responsible for acute osteomyelitis in:

a) adults
b) children?

Answer 11

a) Adults - Staph. aureus

b) Kids - Haemophilus

Question 12

What must be done to open fractures to reduce the risk of osteomyelitis?

Answer 12

Debridement

Question 13

What process gives pathogens an opportunity to spread to bone via blood vessels?

Answer 13

Thrombosis

revise virchow’s triad

Question 14

Which scan is good for picking up osteomyelitis?

Answer 14

MRI scan

Question 15

If there’s pus in a wound, what should you do?

Answer 15

Drain it

Question 16

Why don’t antibiotics help when abscesses are involved in osteomyelitis?

Answer 16

Abscess has no blood supply so antibiotic won’t penetrate it

Question 17

What can the drained pus from an abscess be used for?

Answer 17

Culture

Question 18

What is sequestrum?

Answer 18

Dead bone

Question 19

Does sequestrum has a blood supply?

Answer 19

No

Question 20

Sequestrum should be (removed from / left in) a wound.

Answer 20

removed from

Question 21

What occurs if acute osteomyelitis isn’t treated?

Answer 21

Chronic osteomyelitis

Question 22

If chronic osteomyelitis isn’t treated, where can the pus go?

What happens to bone as a result of the pus?

Answer 22

Joint cavities

Underneath periosteum

More bone death

Question 23

What is an involucrum?

Answer 23

Growth of new bone around sequestrum as seen in osteomyelitis

Question 24

Which joint infection aggressively destroys joints within 1-2 days?

Answer 24

Septic arthritis

Question 25

**Septic arthritis** tends to affect (adults / children).

Answer 25

**children**

Question 26

If a joint space **reappears** on X-ray in a patient with osteoarthritis, what's happened?

Answer 26

**Filled with pus** **Patient has septic arthritis**

Question 27

What conditions are associated with septic arthritis?

Answer 27

**Sepsis** **Septicaemia**

Question 28

Does osteomyelitis lead to septic arthritis?

Answer 28

**Can do** and vice versa

Question 29

What does dark bubbles in soft tissue on a X-ray indicate?

Answer 29

**Gas-forming organisms in soft tissue** Patient may have crepitus

Question 30

Soft tissue infection doesn't produce any pus early on. What are good "best guess" antibiotics used to treat it?

Answer 30

**Flucloxacillin** **Benzylpenicillin**

Question 31

Which soft tissue infection, causing **severe pain**, causes death within days if not treated? What sign may they have on palpation?

Answer 31

**Necrotising fasciitis** Crepitus - gas forming organisms in soft tissue

Question 32

How is necrotising fasciitis treated?

Answer 32

**Removal of all affected tissue**

Question 33

Samples obtained from debridement and pus draining can be used for what?

Answer 33

**Biopsy** **Culture**

Question 34

In which groups of patients should **back pain** be taken very seriously?

Answer 34

Red flag patients **Children** **Teenagers**

Question 35

What is **septic arthritis** called if it's found in the intervertebral discs?

Answer 35

**Discitis**

Question 36

What organism tends to cause discitis?

Answer 36

***Staph. aureus***

Question 37

Patients with discitis are given ___ and only operated on if they don't respond. Why?

Answer 37

**antibiotics** Spine is really difficult to operate on

Question 38

What foreign body, found in joints, can become infected?

Answer 38

**Joint replacements**

Question 39

What types of *Staph.* are associated with prosthetic joint infections?

Answer 39

**Coagulase negative *Staph.*** e.g staph epidermidis

Question 40

What is produced by microbes in joints, making treatment with antibiotics difficult?

Answer 40

**Biofilms** slimy stuff

Question 41

Demarcation of the bone and cement surfaces around prosthetic joints indicates ___ of the joint secondary to what?

Answer 41

**loosening of prosthetic joint** Infection

Question 42

What must be released from infected prosthetic joints?

Answer 42

**Pus**

Question 43

How are operating theatres kitted out to reduce rates of infection?

Answer 43

**Air control** - clean filtered air pumped in via laminar flow diffuser

Question 44

What other factors affect the rate of infection in operating theatres?

Answer 44

**Hand washing** (5 mins) ## Footnote **Neat surgery**

Question 45

What is given to the patient as infection prophylaxis before surgery?

Answer 45

**Antibiotics** 4Cs, flucloxicillin

Question 46

sa and se most responsible for infections mrsE treated with tychoplanin