Hoffa’s fat pad irritation
Hoffitis is the name given to a swelling and/or irritation of Hoffa’s fat pad. This fat pad is located at the front of the knee, behind the patellar tendon that runs down into the lower leg.
Typical symptoms of hoffitis are local swelling and pain under the kneecap. The condition can arise either acutely or over a long period of time.
Description of condition
Named after the person who discovered this knee structure, Hoffa's fat pad is a deposit of fat that fills the space behind the patellar tendon. This fat pad helps nourish and lubricate the knee joint and contains cells that are important for inflammatory processes of the knee. It is also assumed to act as a shock absorber for the knee.
This fat pad can cause problems if it becomes trapped between the bones during extension of the knee. The fat pad then becomes irritated and swollen. The latter is visible in the form of lumps on either side of the patellar tendon. This is known as hoffitis.
Cause and history
Hoffitis may occur acutely, for example, due to a fall or as a result of another problem with the knee. A more gradual development of the symptoms is also possible. In the latter case, there is chronic (long-term) irritation which, at some point, causes (more) symptoms.
People who hyper-extend their knee frequently run a greater risk of developing this condition. This is because the fat pad then has less space and may become trapped. Hoffitis is relatively common in people who run or walk a lot, especially in combination with flat feet.
Signs & symptoms
Hoffitis is accompanied by the following symptoms:
- Pain at the front of the knee.
- Visible local swelling on both sides of the patellar tendon (bulge or thickening).
- Increased symptoms when (hyper)extending the knee or squatting.
The diagnosis of hoffitis is usually made by a (general) physician or physiotherapist. After reviewing the symptoms and the way they arose, a physical examination should follow. This will examine the swelling in the area of the patellar tendon. A special test, in which the Hoffa’s fat pad is put under pressure, will be used to inquire about recognized pain.
If there are acute symptoms, another knee problem needs to be ruled out as a possible cause. This can be achieved by additional testing, such as an MRI. This will also show the fat pad.
Because the fat pad is well supplied with blood, hoffitis generally recovers well. It is important to find out what caused the symptoms and what factors are maintaining the symptoms. Taking sufficient rest and preventing hyperextending of the knee is sufficient in most cases.
It can be useful to have a good look at your gait pattern. If necessary, the fitting of insoles or heel lifts may help prevent hyperextending the knee.
If hoffitis is the result of another underlying knee problem, this should be resolved first. In such cases, hoffitis then often disappears by itself.
In some cases, hoffitis does not heal. In that case, the part of the fat pad causing symptoms can be surgically removed.
Nugteren, K. van & Winkel, D. (2010). Onderzoek en behandeling van anterieure kniepijn. Houten: Bohn Stafleu van Loghum.