- Discussion:
- infected prosthesis can be difficult to evaluate and diagnose;
- however if preoperative aspiration, white cell scan, & sed rate rate are negative, then the chance of doing a successful revision
arthroplasty w/o subsequent infection is good;
- Criteria for Infection:
- at the time of surgery, biopsied material that contains more than 5-10 WBC per HPF (40x) may indicate sepsis;
- sensitivity: about 84% (w/ either 5 or 10 WBC per HPF)
- specificity: 99% using 10 WBC per HPF;
- results are improved by using multiple samples and presence of more than 5 WBC per HPF in more than 5 samples is good evidence for infection;
- for WBC to be counted, they must have defined cytoplasmic borders;
- true positive:
- peri-implant membrane: high concentration of neutrophils is essentially diagnostic of ongoing infection;
- more than 15 neutrophils and, in the absence of an underlying inflammatory arthropathy, strongly supports the diagnosis of infection;
- between 5-15 PMNs supports the diagnosis of infection;
- false negative results:
- in cases where a chronic low grade infection is present (low virulent organism) signs of acute inflammation may be absent;
- in the study by Segawa, et al (1999), only 8 out of 30 patients with chronic joint infection demonstrated signs of acute inflammation;
- Technical Pearls:
- avoid using scar tissue as a sample;
- tissue should for sample should have pink-tan color (as opposed to white scar tissue)
Intraoperative frozen section analysis in revision total joint arthroplasty.
The role of intraoperative frozen sections in revision total joint arthroplasty.
Diagnosis of infection by frozen section during revision arthroplasty.