LOCO 3

Question 1

Structure of spinal column?

Answer 1

There are 33 vertebrae. 7C, 12 T, 5L, 5S, 4C.

They articulate with the vertebral bodies superior and inferior to themselves via articulating facets on their superior and inferior surfaces. These are synovial planar joints.

Question 2

Osteomyelitis commonly affects which vertebrae? [1]

Answer 2

T10 /11

Question 3

Osteomyelitis pathogenesis? [6]

Answer 3

Osteomyelitis may be caused by the haematogenous spread (more common) or non-haematogenous spread of pathogens to bone

Bacteria produce a polysaccharide extracellular matrix, forming a biofilm

Haematogenous osteomyelitis usually involves the metaphysis of long bones in children or the vertebral bodies in adults

In acute haematogenous osteomyelitis, infection spreads through bone via Haversian
and Volkmann canal systems.

The joint is usually spared, unless pus breaks through the metaphyseal cortex forming a subperiosteal abscess in an intracapsular metaphysis, as is found at the proximal radius, humerus, or femur and ankle

capillary anatomy in the metaphyseal area contains venous sinusoids which allow the bacteria to stagnate, while the lower pH and oxygen tension near the growth plate facilitate bacterial growth.

Question 4

Which organism is the most common cause of osteomyelitis? [1]

Answer 4

Staphylococcus aureus

Question 5

Name 4 risk factors for haematogenous spread of pathogen causing osteomyelitis [4]

Answer 5

• Indwelling intravascular catheter (e.g. Hickman line)
• Haemodialysis
• Endocarditis
• IV drug use

Question 6

Osteomyelitis occurring secondary to haematogenous spread in adults most commonly affects which bones? [1]

Answer 6

The axial skeleton, primarily the vertebral bones

Question 7

Which bones being infected increases the chance of septic arthritis? [1]

Answer 7

Less commonly (in adults) long-bone osteomyelitis is seen - which when affecting the metaphysis may lead to septic arthritis.

Question 8

4 causes of non-haematogenous spread causing osteomyelitis? [4]

Answer 8

Skin ulcers
Trauma
Surgery (especially when foreign material is placed)
Animal / insect bites

Question 9

What are the 3 physiological clases of patients of osteomyelitis [3]

Answer 9

• A: people with no comorbidities that compromise outcome; able to withstand surgery and antibiotic
  therapies
• B: those with comorbidities that directly reduce the likelihood of wound healing, reduce the efficacy of
  drug treatment, or increase the risks of surgery
• C: people who are so severely compromised that treatment has an unacceptable risk-benefit ratio, and
  therefore the treatment of their infection can be more harmful than the condition.

Question 10

Osteomyelitis

Haematogenous infection is most associated with bone involvement of which types of bones? [2]

Answer 10

medullary and endosteal bone

Question 11

Risk factors for osteomyelitis? [6]

Answer 11

• previous osteomyelitis (patients may present with an acute exacerbation of a chronic osteomyelitis; Reactivation of a site of osteomyelitis can occur, particularly in older patients)
• penetrating injury
• IV drug abuse
• Diabetes: foot infections occur frequently in patients with diabetes
• HIV
• Recent surgery
• SCA
• RA
• CKD

Question 12

Symptoms [6] and signs [4] of osteomyelitis

Answer 12

symptoms
* Fever
* Pain
* Overlying redness
* Swelling
* Malaise

Signs
* Erythema
* Swelling
* Evidence of previous surgery or trauma
* Tenderness
* Discharging sinus
* Ulcers / skin breaks

Clinical features may reflect aetiology - examples include surgical scar, healing wound or a foot ulcer. In those with haematogenous spread from a central source further signs may be seen. For example osteomyelitis can result from infective endocarditis, if this is suspected listen to the heart for a murmur and check for peripheral and ocular signs of endocarditis. Always consider the underlying cause and evaluate for possible features

Question 14

X-rays often do not show any changes, particularly in early disease.

They cannot be used to exclude osteomyelitis. The potential signs of osteomyelitis on an x-ray are: [3]

Answer 14

Periosteal reaction (changes to the surface of the bone)
Localised osteopenia (thinning of the bone)
Destruction of areas of the bone

Question 15

Which imaging is best investigation for establishing a diagnosis of osteomyelitis? [1]

Answer 15

MRI

Question 16

Investigations for osteomyelitis?

Answer 16

MRI scans are the best imaging investigation for establishing a diagnosis.

Blood tests will show raised inflammatory markers (e.g., WBC, CRP and ESR).

Blood cultures may be positive for the causative organism.

Bone cultures can be performed to establish the causative organism and the antibiotic sensitivities.

Question 17

State what the following mean with regards to imaging of osteomyelitis:

Sequestrum [1]

Involucrum [1]

Cloaca [1]

Answer 17

Sequestrum: Refers to a dead piece of devitalised bone that has been separated (i.e. sequestered) due to necrosis from the surrounding bone.

Involucrum: New growth of periosteal bone around a sequestrum.

Cloaca: An opening in an involuvcrum that allows the internal necrotic bone and pus to discharge out.

Question 18

What history would be suggestive of chronic osteomyelitis [4]

Answer 18

• More vague, non-specific pain
• Low-grade fever of 1 to 3 months’ duration
• Lethargy and malaise
• Fracture fixation
• Acute or old healed sinuses
• Persistent drainage from a wound and/or sinus tract.

Question 19

Describe treatment of osteomyelitis [2]

Answer 19

Surgical debridement of the infected bone and tissues
* Osteomyelitis associated with prosthetic joints (e.g., a hip replacement) may **require complete revision surgery to replace the prosthesis. **

Antibiotic therapy:
* flucloxacillin
* Chronic osteomyelitis usually requires 3 months or more of antibiotics

Question 20

Indications for osteomyelitis surgery is? [3]

Answer 20

• Failure to respond to antibiotic therapy
• Formation of discrete abscess
• Neurological deficit (vertebral osteomyelitis)

Question 21

Spinal TB is most common in which populations? [1]

Answer 21

HIV

Question 22

State two places that primary infection for spinal TB occur [2]

How does this become spinal TB? [1]

Answer 22

The primary infection site is either a pulmonary lesion or an infection of the genitourinary system

Spinal involvement is usually a result of hematogenous spread of M. tuberculosis into the dense vasculature of cancellous bone of the vertebral bodies

Question 23

Symptoms and prensentation of spinal tuberculosis?

Answer 23

The onset is gradual.

Back pain is localised.

Fever, night sweats, anorexia and weight loss.

Signs may include kyphosis (common) and/or a paravertebral swelling.

Affected patients tend to assume a protective, upright, stiff position.

A psoas abscess may present as a lump in the groin and resemble a hernia

Question 24

Investigations for spinal TB? [6]

Answer 24

• MRI is best to assess risk to the spinal cord
• Elevated ESR
• Strongly positive Mantoux skin test
• Spinal X-ray may be normal in early disease, as 50% of the bone mass must be lost for changes to be visible on X-ray: Plain X-ray can show vertebral destruction and narrowed disc space
• Biopsy of bone or synovial tissue is usual: if it shows tubercle bacilli this is diagnostic but usually culture is required
• chest X-ray and, if possible, culture of a spontaneously-produced respiratory sample to exclude or confirm co-existing pulmonary tuberculosis

Question 25

How would Pott’s disease CT scanning present? [1]

Answer 25

Better bony detail of irregular lytic lesions, sclerosis, disk collapse, and disruption of bone circumference.

Question 26

Name and explain this sign of Pott’s disease? [1]

Answer 26

Pott’s Disease Cold Abscess: abscesses typically lack all the inflammatory signs obvious in abscesses

Question 27

What would MRI imaging of Potts disease showcase? [2]

Answer 27

Evaluating disk-space infection and osteomyelitis of the spine and is most effective for demonstrating the extension of disease into soft tissue and the spread of tuberculous debris under the anterior and posterior longitudinal ligaments

Demonstrating neural compression

Question 28

What is the difference between complicated and uncomplicated spinal TB?

Answer 28

Uncomplicated spinal TB is essentially a medical disease

Complicated spinal TB patients need surgical intervention in addition to chemotherapy

Question 29

Treatment for the tubercular infection of Potss Disease? [4]

Answer 29

Isoniazid, Rifampicin, Ethambutol, and Pyrazinamide: 4 months

IR: 2 months

Question 30

What is the first sign of cauda equina? [1]

Answer 30

Urinary retention is first sign of cauda equina

Question 31

Surgical treatment of Pott’s disease?

Answer 31

Spinal fusion or spinal decompression surgeries to correct their structural deformity and prevent further neurological complications