Chapter 52 - Periprosthetic Joint Infections Flashcards
PET for PJI
cannot use until 1 year post op
fluorinated deoxyglucose (FDG) travels to areas of high metabolic activity
How long post op does it take for CRP and ESR to normalize?
21d CRP
90d ESR
IL-6 in PJI
returns to normal in 2-3d of tka
produced by activated macrophages and monocytes
D-dimer threshold in PJI
850ng/ml
what is the WBC threshold for infection in acute (<6wks post op)
10k WBCs, >90%PMNs
what is the WBC threshold for chronic PJI (>6 weeks)
3k WBCs, 80%PMN
if you suspect metallosis, what type of cell count should you order?
manual cell count
pro-con alpha defensin
pro: will still be elevated even if the person has had antibiotics
con: can be fooled by metal debris giving a false positive
what is the definition of acute inflammation for frozen section
> 5 neutrophils/high powered field in 5 HPF
High powered field = 400x magnification
how quickly can a bacteria form a biofilm?
four weeks
pathogenesis of the bacterial biofilm
glycocalyx ECM production which forms a protective scaffolding and facilitates bacterial adherence to the implant surface
what type of bacteria are found in a biofilm
sessile
advantages/disadvantages of dynamic spacer
advantage:
- increased final ROM after reimplantation compared to static spacer
- greater patient satisfaction
- ease of revision
disadvantages:
- possible wound healing issues
- lower doses of intraarticualr antibiotics
advantages/disadvantages of static spacer
advantage:
- higher antibiotic doses intraarticular
- no motion, may be better for wound healing, bacterial eradication
disadvantage:
- worse ROM after reimplantation
- more challenging revision/removal of hardware
indications for debridement with implant retention
- acute development of infection (eg immediately post op <3wks, or immediately after hematogenously seeding)
