MI: Wound, bone and joint infections Pt.2

Question 1

Which imaging techniques are used in septic arthritis

Answer 1

Ultrasound - shows effusion and guides needle aspiration

MRI - shows joint effusion, cartilage destruction, abscess, contigous osteomyelitis

Question 2

How should septic arthritis be managed?

Answer 2

• Antibiotics
• Drainage of the joint (arthroscopic washout) - if infection does not respond to ABx

Question 3

Describe the antibiotic regime in septic arthritis

Answer 3

Flucloxacillin

• 2 weeks IV (OPAT)
• 4 weeks oral

Vancomycin if MRSA

Gonococcal or gram-negative infection - cefotaxime/ceftriaxone

Question 4

What are the two possible ways in which vertebral osteomyelitis can occur?

Answer 4

• Acute haematogenous spread (bacteraemia)
• Exogenous (implant during disc surgery)

Question 5

List some organisms that can cause vertebral osteomyelitis.

Answer 5

• Staphylococcus aureus (48%)
• Streptococcus (43.1%)
• Gram-negative rods (23.1%)
• Coagulase-negative staphylococcus

Question 6

In which region of the vertebral column is vertebral osteomyelitis most common?

Answer 6

Lumbar (43%)

Cervical (10.6%)

Question 7

What are the symptoms of vertebral osteomyelitis?

Answer 7

• Back pain
• Fever
• Neurological impairment

Question 8

List some investigations for vertebral osteomyelitis.

Answer 8

• MRI (90% sensitive)
• Blood cultures
• CT-guided/open biopsy

Question 9

How is vertebral osteomyelitis treated?

Answer 9

Antibiotics (at least 6 weeks)

Surgery if there is spinal cord compression

Question 10

Outline the presentation of chronic osteomyelitis.

Answer 10

• Pain
• Brodie’s abscess - intraosseous abcess
• Sinus tract

Question 11

How is chronic osteomyelitis diagnosed?

Answer 11

• MRI
• Bone biopsy for culture and histology

Question 12

How is chronic osteomyelitis treated?

Answer 12

• Radical debridement down to living bone
• Sequestrectomy - remove sequestra (dead bone tissue) and infected bone disease

Question 13

What are the clinical features of prosthetic joint infection?

Answer 13

• Pain
• Early failure
• Sinus tract

Question 14

Which organism most commonly causes prosthetic joint infection?

Answer 14

• Coagulase-negative staphylococcus
• Staph aureus
• Gram-negative less likely
  Others: streptococci, enterococci, enterobacteriaciae, Pseudomonas aeruginosa, anaerobes

Question 15

How is prosthetic joint infection diagnosed?

Answer 15

• Radiology - shows loosening of the prosthesis
• Joint aspiration WCC (>1700/mL if knee; >4200/mL if hip)

Question 16

How should specimens be taken intraoperatively?

Answer 16

• Specimens should be taken from at least 5 sites around the implant and sent for histology
• NOTE: if 3 or more specimens yield identical organisms, this is suggestive of prosthetic joint infection

Question 17

What is the difference between single stage revision and two stage revision?

Answer 17

Single stage revision

• 1 surgical procedure
• Remove all foreign material and dead bone
• Re-implant new prosthesis with antibody-impregnated cement and give IV antibiotics

Two stage revision

• 2 surgical procedures
• Remove prosthesis and put in a spacer
• Take samples for microbiology and histology
• Period of IV antibiotics for 6 weeks then stop for 2 weeks
• Re-debride and sample at second stage
• Re-implantation with antibody impregnated cement
• If antibiotics are needed, OPAT is used