Those of you with whom I've diagnosed "infrapatellar fat pad impingement" know that it's a tongue-twister of a diagnosis. But what is it? And how do you know if that's the cause of your knee pain?
The infrapatellar fat pad, or Hoffa's fat pad, is a pad of fat which sits just below the knee cap. Its job is to prevent the knee cap from impinging on other structures.
This fat pad is rich in nerve endings, and so it has a lot of capability to cause substantial pain.
These are two ways in which this fat pad may cause pain. One is from a one-off trauma to the fat pad. This may come from a direct blow to the knee, or a forceful extension of the knee causing the fat pad to become pinched.
The other is if the fat pad is being repetitively placed under too much load by repeated extension. People who's knees are able to hyperextend (extend beyond straight) are particularly prone to this problem.
In either of these situations the fat pad will swell and inflammation will cause the nerve endings to become more sensitive. As a result, pain will tend to arise from straightening of the knee.
Treatment of this condition involves unloading the fat pad to give it time to settle. This may include modification of activity levels, taping to lift the patella off the fat pad, and strategies to reduce tone in the quadriceps. Treatments aimed at reducing pain and inflammation, such as icing and ultrasound, are also helpful to speed up recovery.