Introduction: With the growing number of orthopedic procedures, implantation of surgical prostheses has significantly increased. Although less than 10% of patients develop infection-related complications, distinguishing bacterial infection from non-infectious inflammation remains clinically important. The radiopharmaceutical 99mTc-UBI has shown potential to differentiate these conditions. This study evaluated the diagnostic accuracy of 99mTc-UBI imaging in discriminating bacterial infection from non-infectious inflammation in hip and knee arthroplasty implants.
Methods: In this cross-sectional diagnostic study, patients who underwent hip or knee replacement at Rouhani or Shahid Beheshti hospitals in Babol (2021–2024) were regularly followed up at orthopedic clinics. Those with suspected prosthetic joint infection underwent nuclear scanning. The gold standard was two positive cultures from the same microorganism or visible pus during surgery. Scan results were considered positive if delayed-phase uptake in the suspicious joint was equal to or greater than hepatic uptake.
Results: Among 67 patients, 39 (58.2%) had hip and 28 (41.8%) had knee replacements. Based on culture results, 9 patients (13.4%) had prosthetic infection, while scans identified 8 cases (11.9%). The correlation between scan and culture findings was statistically significant (P<0.001). The 99mTc-UBI scan demonstrated 89% sensitivity, 100% specificity, and 98.5% accuracy for overall infection detection. For hip implants, sensitivity was 83%, specificity 100%, and accuracy 96.4%; for knee implants, diagnostic value reached 100%.
Conclusion: 99mTc-UBI imaging provides high diagnostic accuracy in differentiating bacterial infection from non-infectious inflammation in both knee and hip implants. As a non-invasive method, it effectively facilitates clinical follow-up and treatment decision-making.