Bone and Joint Infections

Question 1

Define osteomyelitis

Answer 1

Infection of the bone and marrow

Question 2

What generally causes osteomyelitis (generally speaking)?

Answer 2

An infection

Question 3

List three ways an infection my seed the bone

Answer 3

Hematogenous spread- (less common- seen in children with growing bones)
Contiguous spread
Direct inoculation

Question 4

Describe the pathophysiology of hematogenous osteomyelitis

Answer 4

Bacteremia –> deposition within sinusoidal veins and inflammatory response –> necrosis, abscess formation and sequestration of infarcted bone –> spread under pressure into subperiosteal space

Question 5

What causes sinus formation in bone?

Answer 5

Pressure of dead bone forcing “tracts” through bone for it to escape

Question 6

What is involucrum?

Answer 6

Formation of new bone following infection/death in osteomyelitis

Question 7

What is the most common way bacteria is introduced into bone?

Answer 7

Contiguous infection

DM, ischemic ulcers, decubitus ulcers, trauma/surgery

Question 8

Differentiate spread of infection in newborns/very young vs. older

Answer 8

In younger bones, infection tends to spread directly to the skin (and joint space, in newborns)

In older children, the infection is more contained

Question 9

In what type of osteomyelitis might you not see an elevated white count?

Answer 9

Chronic infection

Question 10

What serum markers may be indicative of a chronic infection?

Answer 10

Elevated ESR, CRP

Question 11

Do gram positive or gram negative organisms most commonly cause osteomyelitis?

Answer 11

Gram positive

Question 12

Which is the most common organisms that causes osteomyelitis?

Answer 12

Staphylococcus aureus

Question 13

Which are the organisms most commonly associated with open fractures/surgery related osteomyelitis?

Answer 13

polymicrobial

Question 14

Which organism causes sickle cell osteomyelitis?

Answer 14

Salmonella

Question 15

Which are the organisms that cause osteomyelitis in neonates?

Answer 15

Hemophilus influenza B, Group B strep

Question 16

Which are the organisms most often responsible for cause osteomyelitis following a shoe/puncture wound?

Answer 16

Pseudomonas

Question 17

WHere does the ideal best culture come from when diagnosing osteomyelitis?

Answer 17

Directly from the bone

Question 18

What is it called when TB infects the vertebral bones?

Answer 18

Pott’s disease

Question 19

Do kids usually have acute or chronic osteomyelitis? Adults?

Answer 19

Acute- kids
Chronic- adults

Difficult to tell them apart clinically

Question 20

What pathogens can cause septic arthritis? Which is an emergency?

Answer 20

Bacteria
Viral
Fungus

Bacterial septic arthritis is an emergency (can lead to joint destruction and loss of joint function)

Question 21

Name a few risk factors for septic arthritis

Answer 21

Old age (>80)
Joint surgery/replacement
IVDU
Endocarditis
Immunosuppression
Joint disease (RA, OA, Gout)
Skin infection/ulcer

Question 22

Is it easy for bacteria and inflammatory cells to enter a joint space?

Answer 22

Yes- the synovial fluid is leaky

Question 23

What causes cartilage/bone necrosis in septic arthritis?

Answer 23

Pressure builds up in joint space/ inflammatory cytokines and proteases

Question 24

How does septic arthritis present?

Answer 24

Acute painful presentation- within hours to day. Decreased ROM, swelling/warmth, elevated white count, accompanied by fever

Extremely painful

Question 25

What is the most important diagnostic test for septic arthritis?

Answer 25

Diagnostic tap

You need to get at fluid to figure out what is causing the inflammation

Question 26

What is the most common cause of septic arthritis?

Answer 26

Staph aureus

second: strep

Question 27

Does an elevated white count distinguish infective vs inflammatory (RA) cause of arthritis?

Answer 27

No- alone it does not

The higher the white count, the more likely it was septic arthritis

Know that sometimes, people can have lower white counts and still have septic arthritis

Question 28

Is a positive gram stain diagnostic for septic arthritis?

Answer 28

yes

Question 29

How do you manage septic arthritis?

Answer 29

Daily aspirations
Surgical drainage
Antibiotics

Question 30

Who gets gonococcal arthritis?

Answer 30

Sexually active <30%

4x more common in women

Question 31

What is the “Classic triad” of gonococcal arthritis?

Answer 31

Dermatitis, tenosynovitis, migratory polyarthralgia

Question 32

Which joints become infected with gonococcus?

Answer 32

Knees- usually monoarticular

Not as painful/acute as someone with classic septic arthritis

Question 33

Describe joint pain with lymes:

Answer 33

migratory, remitting/intermittent, polyarthritis

Cultures are negative. Clinical diagnosis w/ blood test