Clinical Significance of Quadriceps Fat Pad Edema: Its Relation With Anterior Knee Pain and Other Patellofemoral Joint Pathologies

Abstract

Objective: This study aimed to determine the frequency of edematous changes seen in QFP among patients undergoing MRI due to anterior knee pain (AKP) and to elucidate the relation between such changes and other patellofemoral joint pathologies. Materials and Methods: In this retrospective case–control study, individuals with (n=340) and without (n=350) AKP undergoing MRI between January 2018 and January 2020 were evaluated. All images were examined for the presence of QFP edema (QFPE), mass effect and other patellofemoral joint pathologies. The cross-sectional area of QFP was measured and the amount of edema was recorded. Results: QFPE was detected in 79 of the 340 patients with AKP (mean age: 32.29±8.81 years; range: 18–45 years). Mass effects were significantly more common in the AKP group (n=35, 44.3%, p=0.001). The risk of AKP in patients with mass effects was 38.973 times higher compared to patients without mass effects (p=0.001). Patients with diffuse QFPE had a higher risk of AKP than patients with less than 50% edema (p=0.021). Patients with patella alta and increased trochlear sulcus angle had a higher risk of AKP (p=0.029, p=0.006). No other variables were significant risk factors. There was no statistically significant cutoff value for the cross-sectional area. Conclusion: QFPE and mass effects may be associated with AKP independently of other patellofemoral joint pathologies. Therefore, radiologists should be aware of these common findings when analyzing MR images of patients with AKP.