A helpful and promising tool to locate the parts to be treated with IPD’s induction technology
Aims
Arthroplasty surgery of the knee and hip is performed in two to three million patients annually.
Periprosthetic joint infections occur in 4% of these patients. Debridement, antibiotics,
and implant retention (DAIR) surgery aimed at cleaning the infected prosthesis often
fails, subsequently requiring invasive revision of the complete prosthetic reconstruction.
Infection-specific imaging may help to guide DAIR. In this study, we evaluated a bacteria-specific
hybrid tracer (99mTc-UBI 29-41-Cy5) and its ability to visualize the bacterial load on femoral
implants using clinical-gradeimage guidance methods.
Specificity for Stapylococcus aureus was assessed in vitro using fluorescenceconfocal imaging. Topical administration was used to highlight the location of S. aureus cultured on femoral prostheses using fluorescence imaging and freehand single photon emission CT (fhSPECT) scans. Gamma counting and fhSPECT were used to quantify the bacterial load and monitor cleaning with chlorhexidine. Microbiological culturing helped to relate the imaging findings with the number of (remaining) bacteria.
Results
Bacteria could be effectively stained in vitro and on prostheses, irrespective of the presence
of biofilm. Infected prostheses revealed bacterial presence on the transition zone between
the head and neck, and in the screw hole. Qualitative 2D fluorescence images could be complemented
with quantitative 3D fhSPECT scans. Despite thorough chlorhexidine treatments,
28% to 44% of the signal remained present in the locations of the infection that were identified
using imaging, which included 500 to 2,000 viable bacteria.
Conclusion
The hybrid tracer 99mTc-UBI 29-41-Cy5 allowed effective bacterial staining. Qualitative real-time
fluorescence guidance could be effectively combined with nuclear imaging that enables
quantitative monitoring of the effectiveness of cleaning strategies.
Cite this article: Bone Joint Res 2023;12(1):72–79.