Infection prevention and treatment in joint replacement surgery

Question 1

Most common organism and why does it occur?

Answer 1

50% organisms are staphylococci which come from the skin and can occur when the prosthetic joint is put in or can arise after from another place in the body

Question 2

How do we prevent the risk of joint infection?

Answer 2

Antibiotics before surgery
Few people in room during surgery
Laminar flow HEPA filtered surgery room
etc

Question 3

What thing will we look for when diagnosing an infected prosthetic joint?

Answer 3

- History
→ Persistent wound leakage
→ Painful?
→ Period of no pain and then UTI or other infection and then pain in joint?
- Examination
→ Limp, pain when walking?
→ Discharge, swelling?
- X-rays
→ Evidence of being loose?
→ Evidence of periosteal reaction around the prostheses
- FBC, ESR, CRP
→ Elevated WCC
→ ESR and CRP elevated?
- Microbiology culture
→ Definitive diagnosis

Question 4

What is the risk of a joint being infected is CRP >10 and ESR >30? What if there were multiple high ESR and CRP?
What is something we can aspirate from the synovial fluid which offers good sensitivity and specificity for infection?

Answer 4

50% chance of infection.
Multiple = 80% chance.
Alpha defensin = 95% sens and spec.

Question 5

What is key to do in the diagnosis?

Answer 5

Joint aspiration

Question 6

Aims of treatment of joint infection (3)

Answer 6

Eradicate infection, relieve pain and restore function.

Question 7

Treatment options

Answer 7

• Antibiotic suppression - don’t give blind antibiotics.
• Debridement and retention of prosthesis
• Excision arthroplasty
• One stage exchange arthroplasty
• Two stage exchange arthroplasty
• Amputation last resort

Question 8

Why would we use antibiotic suppression?

Answer 8

• Patient unfit for surgery
• Multiple prosthetic joint infections
• Poor distal skin or soft tissues
• Low virulence infecting organisms
• Available oral antibiotics
• Prosthesis not loose
• Will not eliminate sepsis

Question 9

What does debridement involve?

Answer 9

Removing infected prosthetic joint and tissue

Question 10

What is exchange arthroplasty?

Answer 10

• Take out infected prostheses and tissue and replace with new one
• We need to know the organism is and what it is sensitive to
• We need to debride all infected and dead tissue
• Take multiple samples from infected tissue & make sure it matches the micro samples

Question 11

Is 1 stage or 2 stage exchange used more commonly? What do they involve?

Answer 11

2 stage exchange used more commonly

• One stage exchange*
• Debridement, removal of infected prostheses and implant a new prostheses. Cemented and antibiotic load for previous infective organism - 85% success rate
• Two stage exchange*
• More commonly used
• Debridement, local abx spacer which attacks the organisms and systemic antibiotics
• Let infected prostheses settle down for few weeks and then replace when sterile.
• 90-95% success rate