Prosthetic joint infection

Question 1

What is the most serious complication of arthroplasty surgery?

Answer 1

infection!

Question 2

What should be excluded as a cause of prosthesis failure before reconstructing the failed joint?

Answer 2

infection!

Question 3

How common is infection after arthroplasty?

Answer 3

rare

1 in 100

Question 4

What is the trend for the epidemiology of joint infection after arthroplasty?

Answer 4

it is increasing in most types of arthroplasty surgery over the years

Question 5

What are the commonest group of bacteria that cause joint infection after arthroplasty?

Answer 5

CNS - coagulase negative staph (27%)

Question 6

What are the types of bacteria that cause joint infection?

Answer 6

G+ cocci are responsible for 7% of infections - the most common of these is CNS
other G+ cocci that cause joint infections are Enterobacter, MRSA, Enterococcus, anaerobes, pseudomonas
the rest of the infections are caused by S. aureus

Question 7

What is better than treatment of joint infection and why?

Answer 7

prevention is better than treatment!

septic revisions are expensive and protects the pt

Question 8

What are the methods of prevention of infection after arthroplasty?

Answer 8

laminar flow theatres
blood brain barrier 
disposable gowns and hoods 
double glove 
antibiotic loaded cement 
give the pt a single dose systemic antibiotics - flucloaxacillin and gentamycin

Question 9

what is done to diagnose a prosthetic joint infection?

Answer 9

history 
examination 
XR
FBC> ESR, CRP
microbiology culture from DEEP ASPIRATION/ DEEP TISSUE samples

Question 10

what questions may be asked in the history to diagnose joint infection?

Answer 10

was the wound slow to heal after surgery?

recent dental work

Question 11

what is alpha defensin?

Answer 11

it is an inflammatory marker test like CRP and ESR but it is a cytokine and the test has a higher sensitivity/ specificity

Question 12

What must be done before a pt has a deep aspiration of their joint?

Answer 12

make sure than have been off antibiotics for at least 2 weeks!

Question 13

what is the gold standard test for diagnosis of joint infection?

Answer 13

deep aspiration sample which is then sent to microbiology lab to test for organism and sensitivities to antibiotics

Question 14

What are the aims of treatment of an infected joint?

Answer 14

eradicate sepsis
relieve pain
restore function through rehab

Question 15

What are the treatment options for prosthesis infection?

Answer 15

Antibiotic suppression
Debridement, antibiotics and implant retention (DAIR)
Excision arthroplasty
One stage exchange arthroplasty
Two stage exchange arthroplasty
Amputation

Question 16

When is antibiotics suppression used as a treatment option?

Answer 16

when the pt is unfit for surgery eg elderly and frail
multiple prosthetic joint infections
poor distal skin/soft tissues that are likely to get reinfected eg ulcers
low virulence of the infecting organism so likely to be treated by antibiotics
available oral antibiotics - so pathogen is sensitive
pt tolerates antibiotics
prosthesis is not loose

Question 17

Will antibiotics suppression eliminate sepsis?

Answer 17

no

Question 18

What is debridement?

Answer 18

medical removal ofdead, damaged, orinfectedtissueto improve the healing potential of the remaininghealthy tissue

Question 19

What is a DAIR procedure?

Answer 19

Debridement, Antibiotics and Implant Retention

debride the wound, exchange mobile parts (but not removing the whole prosthesis) and then give antibiotics for 6 weeks

Question 20

In which cases is a DAIR suitable for?

Answer 20

EARLY post-op infections or ACUTE haematogenous infections

Question 21

When is a DAIR not suitable?

Answer 21

for chronic infections

if the prosthesis is loose (as it would be better to remove the prosthesis if it was loose)

Question 22

What is excision arthroplasty?

Answer 22

removal of a prosthesis

Question 23

Who is offered an excision arthroplasty?

Answer 23

pts who are high risk and frail with multiple co-morbidities
Pts with low functional demand
Uncontrolled with antibiotic suppression
High risk re-infection due to poor skin or soft tissues

Question 24

What is the disadvantage of doing an excision arthroplasty?

Answer 24

it reduces the functional capacity of the pt as the pt can’t use the limb

Question 25

What can be done instead of excision arthroplasty if the joint is not to be removed?

Answer 25

arthrodesis - ie fusion of the joint

Question 26

What is exchange arthroplasty?

Answer 26

change the infected prosthesis for a new clean prosthesis

Question 27

What does exchange arthroplasty involve?

Answer 27

• Know the organism(s) and their sensitivities
• Debridement of all infected and dead tissue
• Confirmatory intra-operative micro samples
• Appropriate and sufficient antibiotic cover
• Sufficient soft tissue cover/reconstruction
• Sufficient, stable joint reconstruction

Question 28

What is a one stage exchange arthroplasty?

Answer 28

radical debridement with implantation of a new prosthesis that is cemented with antibiotics and pt is given antibiotics depot - ie locally and systemically, but this happens all in the same operation

Question 29

What is a two stage exchange arthroplasty?

Answer 29

radical debridement
place in a temporary antibiotic spacer and give systemic antibiotics targeted towards the organism isolated in this first part of the surgery. Antibiotics are given for 6-12 weeks
there is an interval stage between the two operations where there is no ‘joint’ as such and just the antibiotic loaded spacer
then go back 3 months later after the initial infection has been eradicated and put a new prosthesis in which can be cemented with antibiotics +/- bone graft
then the pt is given routine antibiotic prophylaxis as would after any prosthetic limb surgery