Introduction
To diagnose septic and aseptic loosening 18-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) has been described with good results for hip arthroplasties. The purpose of the present study was to examine whether
there is a difference of feasibility in detecting loosening of hip versus knee prostheses by use of 18F-FDG-PET.
Patients
Thirty-two patients with lower limb arthroplasty complaints (74 components) were studied preoperatively with 18F-FDG-PET. The interpretation of 18F-FDG-PET was done according to evaluated criteria. The final diagnosis based on intraoperative findings in all cases including
microbiological examinations.
Results
For hip arthroplasty sensitivity/specificity of 18F-FDG-PET towards implant loosening was 80%/87%. For infectious loosening of hip endoprostheses sensitivity/specificity was
67%/83%. In knee endoprostheses sensitivity/specificity for loosening was 56%/82% and 14%/89% for infection. The sensitivity
of the results for knee and hip joints in regard to infectious versus aseptic loosening was significantly different.
Conclusion
We confirm that 18F-FDG-PET is an appropriate tool to diagnose hip arthroplasty loosening. Differing from that 18F-FDG-PET showed a significant lower sensitivity/specificity in detecting septic loosening of knee endoprostheses. It may
therefore be necessary to use different methods to diagnose loosening of endoprostheses depending on the type of implant which
is examined.
Keywords
18F-FDG-PET - Arthroplasty - Loosening - Septic - Aseptic