Do Patients Really Have Pain with Quadriceps Fat Pad Edema?

To determine the appropriate MRI criteria for the radiological diagnosis of significant quadriceps fat pad edema, to investigate the relationship between these criteria and anterior knee pain, and to evaluate possible structural and positional factors in the etiology.

In this retrospective case-control study, individuals with and without quadriceps fat pad edema in the knee MRIs taken between May 2016 and December 2018 were determined as the case and control groups, respectively, in a ratio of 1:1. The MRI criteria for significant quadriceps fat pad edema were set as 10 mm and above the anterior-posterior diameter of the quadriceps fat pad, posterior convexity, and an increased signal in the fat-suppressed proton density sequence. The groups were compared for anterior knee pain, pain characteristics, working positions (sitting and standing), and MRI findings of structural factors. P < 0.05 was considered statistically significant.

A total of 108 individuals were evaluated. Anterior knee pain was more common in the case group (49/54, p < 0.001) and was highly correlated with signs of quadriceps fat pad edema (R = -0,657). Frequent pain at night (18/54, p = 0.013), increased pain when walking upstairs (40/54, p = 0.003), knees are flexed (43/54, p < 0.001), and decreased pain when knees are extended (42/54, p < 0.001) were significantly high in the case group. No significant differences were observed in working position and structural factors.

Quadriceps fat pad edema is significantly associated with anterior knee pain and certain specific pain characteristics.