Orthopaedic Infections

Question 1

What type of organisms usually cause osteomyelitis?

Answer 1

Mostly bacteria, sometimes fungi

Question 2

How can organisms get into bone directly?

Answer 2

From penetrating trauma or surgery

Question 3

How can organisms get into bone indirectly?

Answer 3

Haematogenous spread from infection at a distant site

Question 4

Which patients are at increased risk of osteomyelitis?

Answer 4

Immunocompromised, chronic disease, elderly and young

Question 5

What is osteolysis?

Answer 5

An inflammatory response in bone which leads to resorption

Question 6

Once a bone is infected, enzymes from leukocytes cause local osteolysis which causes what?

Answer 6

Pus to form, which impairs blood flow and makes the infection difficult to eradicate

Question 7

What is a sequestrum?

Answer 7

A dead segment of bone

Question 8

Once a sequestrum breaks off in osteomyelitis, how does this alter the treatment?

Answer 8

Antibiotics alone will no longer cure the infection

Question 9

What is an involucrum?

Answer 9

New bone forming around an area of necrosis

Question 10

Acute osteomyelitis, in the absence of recent surgery, usually occurs in who?

Answer 10

Children or immunocompromised adults

Question 11

In children, the sluggish metaphyseal blood flow leads to the accumulation of bacteria and infection spreading towards what part of the bone?

Answer 11

Epiphysis

Question 12

In neonates and infants, certain metaphyses are intra-articular, what is the significance of this?

Answer 12

Infection of bone can spread into the joint causing co-existant septic arthritis

Question 13

Infants have a loosely applied periosteum- what is the significance of this?

Answer 13

An abscess can extend widely

Question 14

What will the onset be of subacute osteomyelitis in children?

Answer 14

Insidious

Question 15

Subacute osteomyelitis in children may lead to the formation of a Brodie’s abscess- what is this?

Answer 15

The bone reacts to an abscess by walling it off with a thin rim of sclerotic bone

Question 16

In adults, in which skeleton does chronic osteomyelitis tend to be?

Answer 16

Axial (spine and pelvis)

Question 17

Chronic osteomyelitis in the axial skeleton of adults usually comes from where?

Answer 17

Haematogenous spread from pulmonary or urinary infections, or discitis

Question 18

Why does chronic osteomyelitis not present earlier?

Answer 18

It gets suppressed by antibiotics and can lay dormant for many years before reactivating

Question 19

What are some symptoms that reactivation of chronic osteomyelitis may cause?

Answer 19

Localised pain, inflammation, systemic upset, discharge

Question 20

What lung infection is known for causing chronic osteomyelitis, especially of the spine?

Answer 20

TB

Question 21

What is the most common organism causing chronic osteomyelitis?

Answer 21

Staph Aureus

Question 22

What organism causing osteomyelitis is unique to patients with sickle cell anaemia?

Answer 22

Salmonella

Question 23

What does it mean if osteomyelitis is classed as ‘diffuse’?

Answer 23

A segment of bone is infected, causing skeletal instability

Question 24

What is the treatment for acute osteomyelitis?

Answer 24

Best guess antibiotics IV, unless there is an abscess which requires surgical drainage

Question 25

If an acute osteomyelitis fails to settle after initial treatment, what should be done?

Answer 25

Second line antibiotics or surgery to gain samples/remove infected bone/washout

Question 26

What are the purposes of surgery fro chronic osteomyelitis?

Answer 26

Gain deep cultures / Remove sequestrum / Debridement

Question 27

What is the complication of surgical debridement of bone?

Answer 27

Instability

Question 28

If surgical debridement of a bone results in instability, what needs to be done?

Answer 28

Internal or external fixation

Question 29

What is the advantage of using external fixation for instability following bone debridement?

Answer 29

The leg can be subsequently lengthened

Question 30

Which populations are at increased risk of osteomyelitis of the spine?

Answer 30

Poorly controlled diabetics, IV drug users, immunocompromised patients

Question 31

If osteomyelitis occurs in the spine, which area does it normally affect?

Answer 31

Lumbar

Question 32

How will patients with osteomyelitis of the spine present?

Answer 32

Insidious onset of back pain which is constant and unremitting

Question 33

Apart from back pain, what are some other symptoms that people with osteomyelitis of the spine might present with?

Answer 33

Paraspinal muscle spasm, fever, systemic upset

Question 34

What tests should you do for osteomyelitis of the spine?

Answer 34

MRI and blood cultures

Question 35

If a patient has osteomyelitis, you should consider which other infection may also be present? How would you test for this?

Answer 35

Endocarditis- ECHO

Question 36

How is a tissue culture obtained for osteomyelitis of the back?

Answer 36

CT guided biopsy

Question 37

What is the treatment for osteomyelitis of the spine?

Answer 37

High dose IV antibiotics (possibly for months)

Question 38

If surgery is required for osteomyelitis of the spine, what can be done?

Answer 38

Debridement, stabilisation and fusion of adjacent vertebrae

Question 39

What aspect of soft tissue injuries can act as a very effective culture medium for bacteria to thrive on?

Answer 39

Haematoma

Question 40

What is the concern when a deep infection complicates a prosthetic joint replacement?

Answer 40

Development of chronic infection with pain, poor function sepsis, discharge and loosening

Question 41

What is the concern when a deep infection complicates a fracture fixation or stabilisation?

Answer 41

Chronic osteomyelitis and non-union of the fracture

Question 42

What are some common virulent organisms which produce an early prosthetic infection?

Answer 42

Staph aureus, gram - bacilli including coliforms

Question 43

What are some organisms which may cause a low grade infection of a prosthetic joint and can present up to a year after surgery?

Answer 43

Staph epidermidis, enterococcus