Hoffa's Fat Pad Impingement

Knee pain is complex and there are different types of knee pain. Front knee pain is one of the most common issues seen among sporting or even the general population, which often affect one’s hobby like running, cycling, hitting the gym or even daily live activities like going up and down the stairs. In this blog, we will be discussing about Hoffa’s fat pad syndrome that is often misdiagnosed as runner’s knee or jumper’s knee, which are more commonly known.

Anatomy of the Fat Pad

So, what is the fat pad, and where is it? Fat pad is just as its name, is clusters of fat tissues that are located around the knee. There are few fat pads at the front of the knee, and the one we are referring to is located below the knee cap. You can actually feel it on your knee – firstly find your knee cap, and just slide your finger just below the knee cap, the soft part that you can move is the fat pad.

Anatomically, it’s sandwiched between the thigh bone (femur), shin bone (tibia), and the knee cap (patella). It is also found to be attached to the knee cap and the meniscuses. The fat pad is a dynamic structure, which it alters position, pressure and volume throughout the knee movement. Its main job is to act as a cushion between the knee cap tendon and the shin bone, as well as provide stability to the knee cap during knee movement. 

The fat pad has been shown to be very pain sensitive. It is rich with nerve endings that can send pain signals to the brain, and therefore people with fat pad problems are often in a lot of pain.

What is the Hoffa’s fat pad syndrome then?

Hoffa’s fat pad syndrome, or Infrapatellar fat pad syndrome, is an acute or chronic inflammation of the infrapatellar fat pad. Usually there are two types of mechanism of injuries that cause the inflammation in the fat pad. First one is a direct trauma, for example a fall on the knee, straightening the knee at high speed. The other one is more commonly seen, which is caused by repeated movement of the knee and leading to the impingement of the fat pad under the knee cap against the thigh & shin bone.

The above two mechanisms will result in inflammation, which leads to swelling and leads to the scenario where the fat pad gets caught even more. Furthermore, with the swelling of the fat pad, it will also alter the movement of the knee cap, forcing the knee to adopt a different way to move, which might cause more damage. 

There is also non-mechanical source of problem in the fat pad, which we refer this as metabolic. It’s associated with obesity and/or osteoarthritis (OA) of the knee.

Alright, then. How do I know if my knee pain is Hoffa’s fat pad syndrome?

It is always being overlooked or misdiagnosed clinically, as it’s symptoms and presentations can be similar to some of the other front knee pains. However, there are a few symptoms that can distinguish Hoffa’s fat pad syndrome from the others

• Tender or pain locally in the fat pad, at the front of the knee, under or the sides of the knee cap tendon (refer to the yellow territory in the first figure)

• Standing / walking are usually painful especially when knee is straightened

• Worse with knee straightened, better if knee is bent slightly

• Worse with flat shoes or barefoot, better with heels

• The fat pad is usually swollen if it’s under inflammation

With that being said, the Hoffa’s fat pad syndrome is usually not a primary disorder, and is more of a secondary disorder. This means the fat pad is rarely injured in isolation, it’s more often caused by another previous or co-existing problem, for example meniscus injuries, ACL tear, or post knee surgery.

Although the exact association of fat pad and knee biomechanics is still being investigated, however, clinically, altered knee biomechanics due to weak hip muscles and poor control of the hip are often found in the Hoffa’s syndrome population. Dynamic knocked knee and tight knee extensors (the quads) can result in impingement of the fat pad and lead to Hoffa’s syndrome. In some cases, poor control of the foot that collapse on the inside (like a flat feet) can also result in knocked knee position, which again can cause impingement of the fat pad. Therefore, a very thorough assessment is needed to find out the root cause of the Hoffa’s fat pad syndrome.

Hmm alright, how do you treat a Hoffa’s fat pad syndrome?

Treatment will depend on how does your fat pad syndrome present to us. If there is inflammation, we will definitely want to reduce the inflammation first before anything else. Dry needling, applying ice, or taking nonsteroidal anti- inflammatory drugs (NSAID, for example ibuprofen) are really good ways to reduce the inflammation. With the cool off of the inflammation, pain will be hugely reduced and your knee will start to feel a lot better. Aside from addressing the inflammation, treating the tightness and tone around the knee, hip or even ankle is also important in reducing the pressure of the knee cap against the fat pad. We do taping sometimes as well to alleviate the pressure off the fat pad.

Once the inflammation of the fat pad has gone down, we will start investigating the root cause of the fat pad impingement. Whether the source is up from the hip, down from the ankle, or localised in the knee itself, there is always something we can do to solve the culprit that is causing the fat pad syndrome. Soft tissue therapy, dry needling, stretching, stabilisation & strengthening exercises are our main treatment methods and they have been proved to be really effective in getting you back to what you love to do.

Sounds good! But, is there anything I can do at home to reduce the pain from this fat pad syndrome?

Ice! Applying ice is always the first and crucial step to reduce the inflammation. You can use cold pack, frozen peas, ice cubes, or anything you can find in your freezer. Just make sure that you wrap a piece of towel or cloth around your choice of ice to prevent ice burn. 

NSAIDs can help with reducing the inflammation, but we do advise that you have a chat with your physician before taking one. 

You should allow a few days to a week’s time for the inflammation to calm down. If yours is more of a chronic issue, meaning you have had the Hoffa’s fat pad syndrome for more than three months, you will want to allow more time that a week for the inflammation to resolve.

So how do you know if the inflammation in the fat pad has reduced? Try touching your fat pad, if it’s less painful or less sensitive, that means inflammation has gone down. You can also tell by noticing the reduction of the swelling, redness, or warmth of the fat pad.

Yesss my inflammation is a lot better now. What are the things I can do at home so that the fat pad doesn’t get impinged and inflamed again?

There are a couple exercises that can be easily done at home to address the common factors that cause fat pad impingement. We will split them into stretching exercises and stability exercises.

Stretching Exercises

The stretches are mainly for structures and muscles that will increase the load and pressure of the knee cap, which will lead to impingement of the fat pad. The commonly seen structures that load the kneecap are the quadriceps, hip flexors, glutes, and iliotibial band (ITB).

Quadriceps

1. There are different ways of doing stretching for quadriceps, but this is more doable by most people.

2. Stand on one leg, and you will be stretching the other one.

3. Place the non-standing knee on something (can be couch, chair, bench, bed), this will help a lot with maintaining the balance so that you can focus solely on the stretch itself.

4. Use the hands to pull the foot towards the glutes, and feel the stretch at the front of the thigh.

5. Moving the knee backwards on the resting object can also help with getting more stretch.

Hip flexors (Psoas major & minor, iliacus)

1. Get into one sided kneeling position (like a proposing pose but with the ankle on the kneeling side resting flat against the ground), you will be stretching the kneeling side.

2. Use a mat or pillow to rest the knee on because it hurts if you kneel on firm ground.

3. Move the foot at the front forward, the front knee angle should be wider than 90 degrees, this allows more range of movement for the stretch.

4. Make sure the pelvis and body do not rotate to one side, they need to be facing straight forward.

5. With the pelvis and upper body as one unit, move them forward and bend the front knee.

6. The further you move forward, the more stretch you will feel on the front of the hip on the kneeling side.

Rectus femoris (hip flexor & also part of the quadriceps)

1. This particular muscle crosses two joints and does two movement, which are lifting the knee up & straighten the knee (hip flexion & knee extension)

2. Get onto one knee with a cushion under, rest the foot/ankle on a bench (you can also rest it against a wall).
   **tip: set up your foot first before the knee

3. The other leg should be at the front with foot firm on the ground. You will be stretching the one with the foot on the bench.

4. Keep your upper body upright, and you will feel the stretch on the back leg.

5. The further you lean back, the more stretch you will feel.

Iliotibial band (and muscles on the side of the hip)

1. You will need a stack of objects, you can use plates in the gym, or pillows at home

2. Get onto the ground, and rest the outside of your foot on the stack. The stretching side will be the side with your foot on the stack.

3. Turn your upper body towards the stretching side, that way your whole body including upper and lower should be facing the same side. 

4. Support your upper body up onto your elbow or if you can, on your hand

5. Move the other leg across so that it is in front of the stretching side, and keep that foot firm on the ground.

6. Roll your pelvis a little more towards where your body is facing, and make sure the knee on the stretching side is straight.

7. You will feel the stretch around the side of the hip that is closer to the ground.

Glutes

1. Lie flat facing up.

2. Bend one knee and move it across to the other side. The bent knee side will be the stretching side.

3. **You should be aiming to move your knee towards the shoulder on the other side, and hug it.

4. Feel the stretch around your glutes, sometimes you can also feel some in your hamstring

5. Do not move your knee across too much as you will start rotating your body and that loses the stretch.

6. If you have tight hip flexors, you will feel a jammy or pinchy sensation at the front of the hip. If you get this, stretch your hip flexors (refer to the above) first before doing this glute stretch.

Stability exercises

If you usually stretch a lot and flexibility is not your problem, then stability & strengthening exercises will be what you need. The exercises we will demonstrate next are mainly to strengthen our gluteus medius, which is a muscle on the side of our hip. Its job is to ensure that the knee is able to maintain in a straight line with the hip and ankle on the same side during activities that require leg movements, for example running, squats, lunges etc. 

If you have weak gluteus medius, you will notice that your knee will cave in during the movements. In some cases, people who have strong gluteus medius might also have caving in of the knee, and that is caused by poor control. The caving in of the knee results in a lot of loads onto the knee and hence the overloading of the knee cap and fat pad impingement.

Clams (banded or not banded)

1. Start with side lying, with your both your knees bent forward at 90 deg.

2. Roll your pelvis forward so that your whole trunk is facing straight forward (very often people tend to leave the pelvis slightly backwards and that will affect the activation of the glute medius).

3. Keep both feet together, lift the top knee away from the bottom one.

4. You should feel the side of your top hip working.

5. If you are using a band, wrap it above your knees.

Monster walk

1. Wrap a band (or use a loop band) slightly above your knee

2. Hinge in your hips, move your glutes backwards and bend your trunk forward

3. Make sure your toes and knees are pointing outwards throughout the whole movement 

4. Move one side of the knee slightly forward and to the side

5. Repeat on the other side
   ** try to use your knees to guide the movement, rather than just stepping forward
   ** knees have to be pointing outwards all the time, even when it’s not moving. The band will force the knees to collapse inwards but you will only work the glute medius when you push the knees against the band

Single leg balancing

• This is a control practice exercise, where you will need to activate the required muscles to maintain the correct form, which is maintaining hip-knee-ankle in the same line.

• Structures & muscles involved will be: glutes, quads, foot muscles, core.

• Mind that this exercise might look easy, but it is very hard to nail every single element.

• It is recommended to do this with barefoot, because cushion in the shoes will affect the balance in your foot, and you want to involve foot in this balance exercise as well.

• Do it in front of a mirror, so that you can see your movement better.

1. Stand on one leg – this is the side you will be working on.

2. Hinge in your hip, move your glutes backwards and bend your trunk forward.

3. Bend your knee slightly, just a tiny bit.

4. ** pay attention and see if your knee is caving in, if it is, stop at the level and do not go any lower, and focus on moving the knee outwards so that hip-knee-ankle are on the same line.

5. ** you should also pay attention to not allowing your pelvis and/or upper body to rotate, both pelvis and upper body should be facing directly forward.

6. Once you are stable, push your hip forward, rather than just lifting your upper body up, this way you work on your glutes rather than allowing the lower back muscles to do the job.

In order to get rid of the inflammation, that will usually take 1-2 weeks to reduce the pain to the minimum. From there, introducing stretching and progressing to stability & strengthening exercises, the whole process will take at least 8 weeks of consistent and precise work. The length of your rehabilitation also depends on what your goal is besides the severity of your fat pad syndrome. 

Elite Health and Performance therapists treat this injury a lot and are really good at pinpointing the root cause of your fat pad syndrome. Pick up the phone or book online to get started on fixing your knee, stopping your pain and get back to what you love to do.