To compare the diagnostic accuracy of Dual-Energy CT (DECT) with Single-Energy CT (SECT) and Conventional Radiography (CR) in detecting knee prosthesis loosening, by using surgery as reference for diagnosis.

This prospective, single-center study conducted between January 2020 and October 2020 included consecutive patients with unilateral painful knee prosthesis. Five radiologists (with a range of experience between 22 and 4 years) evaluated the images independently, diagnosing loosening in the case of radiolucency areas >2 mm in the peri-prosthetic site. Surgery was used as a reference in diagnosis. A multi-reader multi-case analysis was performed to calculate AUC, sensitivity and specificity; these values ??were compared by ANOVA test. A p value <0.05 was considered significant.

The study population consisted of 92 participants with a mean age of 70 years (SD 9.4 years; 25 males, 67 females). Tibial and femoral loosening was diagnosed surgically in 47 and 25 participants, respectively. Regarding the tibial analysis, sensitivity and specificity were 87% and 87% for DECT, 82% and 83% for SECT and 74% and 86% for CR, respectively. For the femoral analysis, sensitivity and specificity were 78% and 84% for DECT, 68% and 76% for SECT, and 60% and 74% for CR, respectively. We achieved an increase in diagnostic accuracy using DECT images compared to SECT (p = 0.13 and p <0.001) and CR (p <0.001). Furthermore, SECT obtained better results than CR (p = 0.07; p = 0.03).

DECT habetter diagnostic accuracy than SECT and CR in the diagnosiof mobilization of knee prostheses.

DECT is a reliable tool for identifying signs of loosening around knee prosthesis. DECT could be employed to diagnose loosening of knee prosthesis in case of doubtful radiographies.