Also known as “Hoffa’s syndrome”, fat pad impingement refers to the fat pad in the front of the knee joint becoming pinched between the kneecap (Patella) and the underlying leg bone.
The fat pad (Hoffa fat pad) is an intracapsular but extrasynovial structure in the knee joint and helps to maintain integrity of the knee structures (Teichtahl et al., 2015). Since it is extremely innervated, pain occurs whenever this structure is impinged by either swelling or through injury.
Injury can occur when the knee is forcibly straightened ie kicking or landing from a jump which in turn can cause the bottom of the kneecap to dig into the fat pad.
Impingement also occurs when the fat pad is pinched if it is enlarged or swollen. This can occur with repetitive minor pinching, or following damage to the fat pad such as occurs during arthroscopic surgery. This results in it bulging around the bottom of the kneecap making it more susceptible to being pinched.
Management involves following the RICE regime (rest, ice, compress and elevate), and Physiotherapy treatment for strengthening and pain modulation.
Teichthal A.J. et al., 2015, A large infrapatellar fat pad protects against knee pain and lateral tibial cartilage volume loss, Arthritis Research & Therapy, 17, p: 318