Effects of Insall-Salvati ratio and obesity on suprapatellar fat pad

This study aimed to evaluate the effect of Insall-Salvati ratio and obesity on signal and shape changes in the suprapatellar fat pad and investigate their role in impingement.
A total of 124 patients who underwent magnetic resonance imaging examination of the knee between January and November 2018 were included in the study. The ratio of the length of the patellar tendon to patella was calculated for the Insall- Salvati ratio. The thickness of subcutaneous fat tissue was measured from the medial of the knee as an indicator of obesity. The relationship between suprapatellar fat pad signal and shape changes, Insall-Salvati ratio, subcutaneous fat tissue thickness, quadriceps and patellar tendon thickness, and demographic data were statistically analyzed.
Of the patients, 59 (47.6%) were women and 65 (52.4%) were men. In 56 (45.2%) patients, the suprapatellar fat pad had signal changes compatible with those of edema. Moreover, 77 (62.1%) patients had a mass effect on the adjacent joint space due to convexity in the suprapatellar fat pad posterior contour. Although the mass effect was found in 63.6% (49) of the patients with edema in the suprapatellar fat pad, it was missing in 85.1% (40) of the patients without edema in the suprapatellar fat pad (P < 0.001).
This study showed that although a significant relationship existed between the presence of edema and mass effect in the suprapatellar fat pad, the Insall-Salvati ratio and obesity had no significant effect on suprapatellar fat pad impingement.