Osteomyelitis & Septic Arthritis

Question 1

What is osteomyelitis?

Answer 1

Inflammation in a bone or bone marrow, usually caused by bacterial infection.

Question 2

Define haematogenous osteomyelitis

Answer 2

When a pathogen is carried through the blood and seeded in the bone (i.e. remote source of infection e.g. cannula, IVDU)

Question 3

What is the most common mode of infection in osteomyelitis?

Answer 3

Haematogenous osteomyelitis

Question 4

What is nonhaematogenous osteomyelitis associated with?

Answer 4

Direct inoculation via trauma or medical procedures

Question 5

What pathogen causes most cases of osteomyelitis?

Answer 5

Staph. aureus

Question 6

Give 3 conditions associated with osteomyelitis

Answer 6

1) Diabetes

2) Peripheral arterial disease

3) Sickle cell disease

Question 7

How can diabetes lead to osteomyelitis?

Answer 7

Poorly controlled diabetes with associated peripheral neuropathy:

1) impairs blood supply

2) this can lead to the development of non-healing infected ulcers and 2ary nonhaematogenous spread of the associated pathogens to bone

Question 8

How can PAD lead to osteomyelitis?

Answer 8

Through a similar process to diabetes

Question 9

How can sickle cell disease lead to osteomyelitis?

Answer 9

Sickle cell can cause infarction of the bone and bone marrow leading to secondary infection

Question 10

What are the key risk factors for developing osteomyelitis?

Answer 10

1) Open fractures

2) Orthopaedic operations, particularly with prosthetic joints

3) Diabetes, particularly with diabetic foot ulcers

4) Peripheral arterial disease

5) IV drug use

6) Immunosuppression

Question 11

Infection in a prosthetic joint is a big problem.

When is this more likely to occur?

Answer 11

In revision surgery rather than during the initial joint replacement.

Question 12

What can be done to reduce the risk of infection in prosthetic joints?

Answer 12

Perioperative prophylactic antibiotics

Question 13

Osteomyelitis can be acute or chronic.

What are the features of acute osteomyelitis?

Answer 13

• Pain
• Warmth
• Erythema
• Swelling of the soft tissue surrounding the affected bone
• Systemic e.g. fever, malaise

Question 14

What is the imaging of choice in suspected osteomyelitis?

Answer 14

MRI

Question 15

What investigations can be done in suspected osteomyelitis?

Answer 15

1) MRI scan

2) Bloods: WBC, CRP, ESR

3) Blood cultures

Question 16

Mx of osteomyelitis?

Answer 16

1) Abx

2) +/- surgical debridement

Question 17

1st line Abx in osteomyelitis?

Answer 17

6 weeks of flucloxacillin, possibly with rifampicin or fusidic acid added for the first 2 weeks

Question 18

If MRSA is suspected in osteomyelitis, what Abx should be given?

Answer 18

Vancomycin or teicoplanin

Question 19

How long is abx treatment in acute osteomyelitis?

Answer 19

6 weeks

Question 20

What can be used as an alternative to flucloxacillin in the mx of osteomyleitis in a penicillin allergy?

Answer 20

Clindamycin

Question 21

How long is abx treatment in chronic osteomyelitis?

Answer 21

Chronic osteomyelitis usually requires 3 months or more of antibiotics.