Osteomyelitis

Question 1

Osteomyelitis is an infection of the bone characterised by progressive inflammatory destruction. What is the prevalence (number of new cases in a specified time frame) of osteomyelitis?

1 - 2-5 / 10,000
2 - 25-50 /10,000
3 - 250-500 / 10,000
4 - 2500-5000 / 10,000

Answer 1

1 - 2-5 / 10,000
- can be higher in developing countries

Question 2

Which of the following is the most common cause of osteomyelitis?

1 - viral
2 - fungal
3 - bacterial
4 - protozoa

Answer 2

4 - protozoa

Question 3

Are younger or older patients generally affected?

Answer 3

• both
• bimodal effects, where <20 or >70 y/o

Question 4

What is the most common microorgaism that leads to osteomyelitis?

1 - Klebseilla
2 - Escherichia coli
3 - Staphylococcus aureus
4 - Clostridium difficile

Answer 4

3 - Staphylococcus aureus
- a grape like Gram negaitive bacteria

Question 5

Which of the following is NOT typically a risk factor for oestomyelitis?

1 - diabetes
2 - male
3 - immunocomprimised
4 - IV drug user
5 - recieving haemodialysis

Answer 5

2 - male

Occur in 15% of diabetic patients, and 20% of these have amputations

Question 6

In a patient with a foot ulcer, which of the following can increase the risk of developing ostyeomylitiis?

1 - Visible bone
2 - Ability to probe to bone
3 - Ulcer size >2cm x 2cm
4 - Ulcer depth >3mm
5 - Ulcer duration >1-2 weeks
6 - ESR >70 mm/hr
7 - all of the above

Answer 6

7 - all of the above

Question 7

Which part of a bone do microorhansism generally settle that lead to osteomyelitis?

1 - diaphysis
2 - articular cartilage
3 - epiphysis
4 - metaphysis

Answer 7

4 - metaphysis

• location of growth plates
• microorganism are here due to the blood flow
• microorganisms are found at the growing end of the bone

Question 8

Although there are several ways in which bones can become infected causing osteomyelitis. What is the most common way the causative agent is spread?

1 - haematogenous
2 - lymph
3 - immune cells
4 - adjacent osteomyelitis

Answer 8

1 - haematogenous

Question 9

Organise the stages of pathophysiology of osteomyelitis below:

1 - involcrum (new bone formation outside old bone)
2 - acute inflammation and venous congestion
3 - pus moves from medullary to periosteum over 2-3 days
4 - blood supply is comprimised leading the necrosis over 7 days
5 - if bone is salvagable, new bone will begin to form over 10-14 days
6 - suppuration (pus formation)
7 - pocker of dead tissue, called a sequestrum form

Answer 9

2 - acute inflammation and venous congestion
6 - suppuration (pus formation)
3 - pus moves from medullary to periosteum over 2-3 days
4 - blood supply is comprimised leading the necrosis over 7 days
7 - pocker of dead tissue, called a sequestrum form
5 - if bone is salvagable, new bone will begin to form over 10-14 days
1 - involcrum (new bone formation outside old bone)

Question 10

In a patient undergoing dialysis, which 2 of the following bones are more commonly affected?

1 - clavicle
2 - spine
3 - ribs
4 - humerous

Answer 10

2 - spine
3 - ribs

Question 11

In a patient who is an IV user, which 2 of the following bones are more commonly affected?

1 - clavicle
2 - spine
3 - ribs
4 - humerous

Answer 11

1 - clavicle

Question 12

What are the 2 key symptoms a patient is likley to present with if they have osteomyelitis?

1 - pain at site of infection
2 - swollen joint
3 - unable to weight bear or use the joint
4 - fever (if acute)

Answer 12

1 - pain at site of infection

4 - fever (if acute)

Question 13

All of the following are signs a clinician will be able to see if a patient has osteomyelitis, EXCEPT which on:

1 - signs of sepsis if acute
2 - erythema (red skin reaction)
3 - Tenderness
4 - Oedema
5 - Sinus tract if chronic
6 - Limited range of movement of adjacent joints
7 - crepitus at adjacent joints

Answer 13

7 - crepitus at adjacent joints

Question 14

Osteomyelitis can present in a similiar way to other conditions. All of the following are potential differentials, which is the LEAST likely?

1 - Benign tumour
2 - Malignant tumour
3 - Healing fracture
4 - Septic arthritis

Answer 14

4 - Septic arthritis

Question 15

An X-ray can be used to investigate a patient with suspected osteomyelitis. But is the X-ray always useful?

Answer 15

1 - no
- if acute, the scan can be normal for up to 2 weeks

MRI is the next best option, but bone biopsy and culture are also diagnositc

Question 16

An X-ray can be used if we suspect a patient has osteomyelitis. However, in an acute setting the x-ray can be normal for up to 2 weeks. What % of bone loss has to be present before it can be detected on X-ray?

1 - 10%
2 - 25%
3 - 50%
4 - >75%

Answer 16

3 - 50%

Question 17

In a patient with chronic osteomyelitis we may see all of the following features, EXCEPTY which one?

1 - patchy lucency (bone is no longer white, appears darker)
2 - new periosteum bone formation
3 - sequestrum (appears radiodense compared to osteopenic surrounding
4 - fracture

Answer 17

4 - fracture

• sequestrum is necrotic bone that has been surrounded by granulation tissue

Question 18

Which of the following is NOT a typically raised blood marker in a patient with suspected osteomyelitis?

1 - WBC
2 - CRP
3 - LFTs
4 - Erythrocyte Sedimentation Rate (ESR)

Answer 18

3 - LFTs

• we would need to measure LFTs, U&Es and glucose though

Question 19

In a patient with suspected osteomyelitis, we need to take samples and send for all of ther following, EXCEPT which one:

1 - gram staining
2 - cell counts
3 - blood culture
4 - cell culture
5 - crystal analysis

Answer 19

5 - crystal analysis

• gout and pseudogout are unlikley

Question 20

In a patient with osteomyelitis, which of the following is NOT part of the conservative management approach?

1 - amputate
2 - pain relief by bed rest
3 - analgesia
4 - splintage

Answer 20

1 - amputate

Question 21

In a patient with osteomyelitis, which of the following is NOT part of the conservative management approach?

1 - amputate
2 - pain relief by bed rest
3 - analgesia
4 - splintage

Question 22

Once a patient with osteomyelitis has had blood and pus cultures, which antibiotic is typically given IV to treat osteomyelitis?

1 - vancomyocin
2 - co-amoxiclav
3 - flucloxacillin
4 - penacillin

Answer 22

3 - flucloxacillin

• if penacillin allergy then can use clindamyacin

Question 23

Once a patient with osteomyelitis has had blood and pus cultures, flucloxacillin is typically given IV to treat osteomyelitis. This is generally given at a high dose for how long?

1 - 6 hours
2 - 6 days
3 - 6 weeks
4 - 6 months

Answer 23

3 - 6 weeks

Question 24

Which of the following is NOT typically a surgical treatment for patients who do not respond to conservative management for osteomyelitis?

1 - amputation
2 - irrigation and debridement
3 - joint replacment

Answer 24

3 - joint replacment

Question 25

Patients with osteomyelitis are typically treated and cured., However, what is the risk of malignancy?

1 - 1%
2 - 10%
3 - 20%
4 - 50%

Answer 25

1 - 1%

Question 26

What is the imaging of choice in osteomyelitis?

1 - CT scan
2 - X-ray
3 - MRI
4 - ultrasound

Answer 26

2 - X-ray

MRI is second

Question 27

Necrobiosis lipoidica is a rare granulomatous skin disorder typically described on the shin of diabetics.

• Uncommon, but seen in diabetic patients and sometimes Rh arthritis
• Hardened erythematous skin patches with yellowing centre
• Due to collagen degeneration

Answer 27

• Patients are usually asymptomatic
• Can be sore or itchy (esp. if injured)

No curative Rx:
- PUVA
- Local steroids