Bone and Joint Infections

Question 1

Osteomyelitis

Answer 1

Inflammation of bone and marrow due to infection

Question 2

What are the different causes of osteomyelitis?

Answer 2

• Hematogenous

- Contiguous

Question 3

What population is most likely to have hematogenous spread of osteomyelitis?

Answer 3

Children due to growing bone taking up more of the blood supply

Question 4

What is the pathogenesis of acute osteomyelitis?

Answer 4

Infection at a focal point in the bone can lead to blockage of arteries leading to decalcification while proteolytic enzymes destroy bacteria leading to increased intramedullary pressure

Question 5

What is the pathogenesis of chronic osteomyelitis?

Answer 5

Inadequate treatment of acute osteomyelitis leads to the continuation of the inflammatory process and eventual bone necrosis followed by new bone formation (involucrum) and possible sinus formation in the involucrum.

Question 6

What is the cause of contiguous osteomyelitis?

Answer 6

Extension from proximal infection - examples are ulcers from diabetes or infection from trauma/surgery

Question 7

Where does osteomyelitis spread in children?

Answer 7

Infection often spreads out to the skin

Question 8

Where does osteomyelitis spread older patients?

Answer 8

Infection tends to stay in the bone

Question 9

What are the typical pathogens of osteomyelitis?

Answer 9

• Staph
• Strep
• Enterococcus and Gram Negative Rods (more rare)

Question 10

What is the the MOST common pathogen for osteomyelitis?

Answer 10

S. aureus

Question 11

What is the most likely pathogen for osteomyelitis due to a puncture wound?

Answer 11

Pseudomonas

Question 12

What is the most likely pathogen for osteomyelitis in those with sickle cell anemia?

Answer 12

Salmonella

Question 13

What is the most useful lab test for diagnosis of osteomyelitis?

Answer 13

Bone biopsy with a culture

Question 14

What is the best imaging to use for osteomyelitis?

Answer 14

MRI

Question 15

A 60 yr old man with type 1 DM has a chronic ulcer over R sole of foot. It has been draining pus for weeks. No fevers, pain. On PE, he is AF. There is a draining sinus tract on R sole of foot. Culture from the pus grow E.coli and enterococcus faecalis. Placement of a steel probe through the sinus tract goes to bone. Which of the following should be done next?
• A.ObtainX‐ray
B. Obtain MRI
C. Start Vancomycin and Zosyn
D. Start oral clindamycin and levofloxacin
E. Schedule bone biopsy

Answer 15

E. Schedule bone biopsy

Question 16

What is the probe bone test?

Answer 16

Probing to the bone in an ulcer requires no further testing to classify as osteomyelitis

Question 17

What can 2 vertebrae back to back affected by osteomyelitis indicate?

Answer 17

Tuberculosis Osteomyelitis

Question 18

Septic Arthritis

Answer 18

Rapid joint destruction, irreversible loss of function - often due to bacterial infection

Question 19

How serious is septic arthritis?

Answer 19

EMERGENCY - 50% with permanent loss of function

Question 20

What are some risk factors for septic arthritis?

Answer 20

• Age greater than 80
• Recent joint surgery
• IV drug use
• Endocarditis
• Joint diseases (RA/OA/Gout)

Question 21

A 65 yr old woman with RA has a 1d hx of pain and swelling of the 3rd R PIP joint. Current Meds are: Prednisone, Methotrexate. On PE: T39.2, rest wnl. The joint is warm, erythematous, tender and has decreased range of motion (ROM). What do you do?:
A. Prescribe colchicine
B. Treat her for a RA flare 
C. Perform diagnostic tap 
D. Prescribe ampicillin

Answer 21

C. Perform diagnostic tap

Question 22

What is the main diagnostic test for septic arthritis?

Answer 22

Diagnostic Tap

Question 23

Does a negative Gram stain rule out septic arthritis?

Answer 23

NO

Question 24

What are the main causes of septic arthritis?

Answer 24

• S. aureus
• Strep

Much less common:

• E. coli
• Neisseria
• Pseudomonas

Question 25

What WBC levels increase risk for septic arthritis?

Answer 25

Higher WBC levels increase the risk fro septic arthritis

Question 26

A 65 yr old woman with RA has a 1d hx of pain and swelling of the 3rd R PIP joint. Current Meds are: Prednisone, Methotrexate. On PE: T39.2, rest wnl. The joint is warm, erythematous, tender and has decreased ROM. Examination of purulent fluid aspirate from the joint is negative for crystals. Which of the following organisms is the most likely cause?

A.Strep pyrogenes 
B.Strep agalactiae 
C.Staph aureus 
D.Pseudo aeruginosa
E. Salmonella Enteritidis

Answer 26

C.Staph aureus

Question 27

What is the population for gonococcal arthritis?

Answer 27

Most common in sexually active individuals less than 30 yrs of age

Question 28

What gender gets gonococcal arthritis more?

Answer 28

Females

Question 29

What is the presentation triad of disseminated gonococcal infection?

Answer 29

• Dermatitis
• Tenosynovitis
• Migratory polyarthralgia or arthritis

Question 30

25 yr old man from Hawaii had a 2d hx of severe R wrist pain. The pt is sexually active with multiple partners and infrequently uses condoms. On PE, his T38.9, HR: 100, BP: 100/70. Exam reveals erythema and swelling and decreased ROM of R wrist. His serum WBC in 18,000. What is the most likely causative micro‐organism?
A. Staph aureus
B. Strep agalactiae
C. Neisseria gonorrhea
D. Ebstein Barr Virus
E. Borrelia burgdorferi

Answer 30

C. Neisseria gonorrhea

Question 31

What are symptoms of lyme arthritis?

Answer 31

Polyarticular, intermittent and relapsing arthritis - can be migratory

Question 32

What is the most common site for lyme arthritis?

Answer 32

Knee