An anatomo-radiological study of the infrapatellar fat pad

The infrapatellar fat pad (IFP) is an intracapsular, but extrasynovial structure, located between the patellar tendon, femoral condyles and tibial plateau. We have recently described the microscopic orgnisation of the IFP, which consists of white adi- pose tissue (fbroadipose, lobular type), organised in lobuli delimited by thin connec- tive septa. The aim of the study is to describe the sonoanatomical features of IFP in subjects without knee pathology during fexo-extension movements. Twentyfour vol- unteers subjects with no history of knee diseases (5M, 19F, mean age: 45yo)were ana- lysed. Examinations was performed using high-resolution grey-scale ultrasound. The mean area of the deepest recognisable adipose chamber in extension were 0,12 and in fexion 0,19 mm , and the circumference were in extension 1,36 and in fexion 1,19 mm. The area of the closest adipose chamber to the patellar tendon were in exten- sion 0,29 and fexion 0,12 mm (p<0.01), whereas the circumference were in extension 2,67 and in fexion 1,56 mm(p<0.01). Our study demonstrated that the normal IFP is constituted by largest lobuli in the superfcial part(p<0.01) that become fattened in fexion movement. The deep lobuli are smaller and do not change their morphology. Our study demonstrated that ultrasound is useful to analyse the dynamic changes of the IFP.