quadriceps fat pad impingement
An inflammatory process affecting the anterior suprapatellar fat, which is seen on MRI as a high T2 signal, low T1 signal and a mass effect on the quadriceps tendon. It is characterised by excess fat, and may follow mild anterior knee trauma, especially if the fat pad is large, and compressed between the tibia and femur when the bent knee is extended suddenly. It is often accompanied by quadriceps laxity.
Quadriceps fat pad (arrow) is hyperintense on the sagittal T2 fat sat image (A) and hypointense on sagittal T1 image (B) Bas A, et al. BMJ Case Reports 2012. doi:10.1136/bcr-2012-007643
Examination Positive Hoffa sign
Average age 38 years
Clinical findings Anterior knee pain; effusion and signs suggestive of ligament instability
Synonyms Fat pad impingement, fat pad syndrome, Hoffa’s disease, Hoffa’s syndrome, solitary lipoma of the knee, suprapatellar fat pad syndrome