MSCT Week 3: Osteomyelitis

Question 1

Osteomyelitis description

Answer 1

Inflammation of bone that is almost always due to an infection, typically bacterial (pyogenic osteomyelitis) and may be acute or chronic

Question 2

Pyogenic Osteomyelitis AKA

Answer 2

Bacterial osteomyelitis

Question 3

Signs and symptoms of osteomyelitis

Answer 3

• Fever
• pain in the area of infection
• warmth and redness over the area of infection

Question 4

Osteomyelitis risk factors

Answer 4

• Any age
• 2-12 is most common
• more common in males

Question 5

Pathogenesis of Osteomyelitis

Answer 5

usually results from haematogenous spread in which bloodborne organisms, usually bacteria, are deposited in the medullary cavity and form a nidus infection

Question 6

Osteomyelitis: Region in long bones most predisposed to infection

Answer 6

metaphysis because it has a large supply of slow-flowing blood which is an ideal environment for bacteria to accumulate and proliferate

Question 7

Osteomyelitis from contiguous spread

Answer 7

infections originating from soft tissues and joints can spread to bone which often occurs in the context of vascular insufficiency such as patients with diabetes mellitus or peripheral vascular disease

Question 8

A contiguous spread of osteomyelitis is from?

Answer 8

Soft Tissues to bone usually in vascularly impaired patients DM, Vasculitis

Question 9

Haematogenous spread is from

Answer 9

Blood to bone

Question 10

The contiguous spread is most common in people with

3 listed

Answer 10

• vascular deficiencies such as DM or peripheral vascular disease
• there is a diminished immune response secondary to poor perfusion of the infected region
• in these patients, the lower extremities are most commonly affected as there is associated peripheral neuropathy which predisposes to repeated microtrauma.

Question 11

Osteomyelitis: Direct Inoculation

Answer 11

Direct seeding of bacteria into bone can occur as a result of open fractures, insertion of metallic implants or joint prostheses, human or animal bites and puncture wounds

Question 12

Osteomyelitis most common infectious agent

Answer 12

Staphylococcus aureus

Question 13

Staphylococcus aureus accounts for how much of Osteomyelitis?

Answer 13

80-90% of infections

Question 14

Pathogen common in IVDU and Genitourinary tract infections

Answer 14

Escherichia Coli or Pseudomonas spp.

Question 15

Osteomyelitis: Infectious agents common in Sickle Cell Disease

Answer 15

Salmonella

Question 16

Osteomyelitis: Infectious agents common in Neonates

Answer 16

• Haemophilus influenzae
• Group B streptococci

Question 17

Mycobacterial Osteomyelitis

Answer 17

typically affects 1-3% of individuals with pulmonary or extrapulmonary tuberculosis

COMMON SITE OF INFECTION IS SPINE 40% OF ALL CASES

Question 18

Osteomyelitis: Acuity

Answer 18

Osteomyelitis may be acute or chronic

Question 19

Acute Osteomyelitis: hematogenous spread or direct inoculation

Answer 19

• bacterial proliferation within the bone induces an acute suppurative response
• there is an accumulation of pus within the medullary cavity leading to raised intramedullary pressure and vascular congestion which can disrupt intraosseous blood supply
• the rise in intramedullary pressure can lead to rupture of the bony cortex, producing a cortical defect known as a cloaca
• Intramedullary pus can spread outward through the cloaca and form a subperiosteal abscess
• This causes elevation of the periosteum and disrupts the periosteal blood supply to the bone
• Continual accumulation of pus in the subperiosteal space leads to rupture of the periosteum and spread of infection to soft tissues through a channel between the bone and skin surface known as a sinus tract

Question 20

Chronic Osteomyelitis

Answer 20

• If Acute Osteomyelitis is inadequately treated, there will be a progression of the disease to chronic osteomyelitis
• The pathological features of chronic osteomyelitis are a result of osteonecrosis caused by a disruption of the intraosseous and periosteal blood supply during the acute stage of disease
• a fragment of dead infected bone becomes separated from the viable bone and is known as a sequestrum
• The bacteria within the revascularized sequestrum are protected from antibiotics and the endogenous immune response thus forming a nidus for chronic infection which may persist for many years
• in an attempt to wall of the sequestrum, an inflammatory reaction characterized by osteoclastic resorption and periosteal new bone formation occurs
• The sequestrum becomes surrounded by pus, granulation tissue and a reactive shell of new bone known as involucrum
• The involucrum may have cloaca through which the pus can be discharged

Question 21

Identify

Answer 21

Question 22

Identify

Answer 22

Question 23

Osteomyelitis Diagnosis

7 Listed

Answer 23

• Radiographic evaluation
• Blood Tests
• WBCs are usually normal even in acute osteomyelitis
• ESR and CRP are often elevated (but lack specificity without radiographs and microbiological data)
• CRP may be more reliable than ESR for assessing response to treatment in children
• Blood cultures should always be obtained when osteomyelitis is suspected though they are often negative except in cases of hematogenous osteomyelitis
• GOLD STANDARD FOR DIAGNOSIS OF OSTEOMYELITIS IS NEEDLE BONE BIOPSY WITH HISTOPATHOLOGIC EXAMINATION AND MICROBIAL CULTURES

Question 24

Treatment of Osteomyelitis

3 listed

Answer 24

• Typically intravenous antibiotics, usually for extended periods
• if a sequestrum and involucrum is present then drainage and / or surgical debridement is often necessary
• Although uncommon with use of antibiotic regimens, amputation may be necessary with failure of medical therapy or when the infection becomes life threatening