Correlation study of infrapatellar fat pad EI in assessing clinical symptoms of knee osteoarthritis

Infrapatellar fat pad (IPFP) is considered a marker for disease progression in knee osteoarthritis (KOA), but currently no ultrasound parameters effectively quantify abnormal changes in IPFP. To investigate the correlation between clinical symptoms of KOA and semi-quantitative ultrasound scores as well as the echo intensity (EI) of the IPFP, and investigate the correlation between the IPFP EI and knee joint effusion and synovium. This study included 75 patients with primary KOA. Ultrasound semi-quantitative scoring of the knee joint and measurement of IPFP EI were performed. Patients' Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and Visual Analog Scale (VAS) scores were assessed. Spearman correlation analysis was used to compare the correlations between these two symptom scores and the ultrasound semi-quantitative score and IPFP EI. The correlation between IPFP EI and joint effusion and synovium was also compared. Ordered logistic regression analysis was performed to determine the factors influencing clinical symptoms of KOA. Correlation analysis reveals that VAS scores, WOMAC pain scores, stiffness scores, and functional scores all show a positive correlation with IPFP EI. Synovial thickening also exhibits a positive correlation with IPFP EI. Ordered logistic regression analysis demonstrates that IPFP EI is an independent and significant predictor of KOA symptom severity. In summary, synovial thickening shows a significant correlation with IPFP's EI. The stronger the echo of the IPFP, the more severe the clinical symptoms of KOA. This may offer a new perspective for ultrasound in assessing the severity of KOA patients.