Abstract
Aim
The effectiveness of mandatory joint aspiration prior to re-implantation in patients with a cement spacer already in place is unclear.
The aim of this study was to evaluate the role of culturing articular fluid obtained by joint aspiration prior to re-implantation in patients who underwent a two stage septic revision.
Method
A retrospective observational study was conducted, assessing51 patients that underwent a two stage septic hip or knee revision from 2010 to 2017.
According to the results of intraoperative cultures, after the first stage revision each patient was treated with an antibiotic protocol for 6–8 weeks. Following two weeks without antibiotics, a culture of synovial fluid was obtained. Synovial fluid was obtained by direct joint aspiration in cases of knee spacers by and by joint aspiration guided by fluoroscopy in the theatre room in cases of hip spacers. Synovial fluid was transferred into a Vacutainer ACD® flask. Samples were processed and analysed in the microbiology laboratory. Gram stains were performed and the sample was subsequently transferred into a BacALERT bottle (bioMérieux, France) and incubated in a BacALERT instrument for seven days.
Results of these cultures were recorded and compared with cultures obtained during re-implantation surgery.
Results
Of the 51 patients analysed, 9 were excluded because joint aspiration was not performed or the samples were not correctly processed. The remaining 42 patients (21 hip and 21 knee spacers) were included in the final analysis. In 40 cases, the culture of synovial fluid was negative while in the remaining two cases (hip spacers) no analysis was possible due to dry aspiration. In 5 of the patients, two or more intraoperative synovial fluid cultures taken during the re-implantation surgery were positive.
Conclusions
Although in theory, synovial fluid culture may provide useful information regarding the infection status of the joint, in our study, we found no evidence to support mandatory joint aspiration prior to re-implantation in patients with a cement spacer in place.
