I am currently treating a patient who is having pain in her left knee. She has a lot of pain below the kneecap but also pain along the IT band. After examining her, she doesn’t just have one thing going on. She has several. Her kneecap is not tracking correctly because of her IT band tightness. Also she is incredibly weak in her hip and knee muscles. Because of this she stands in knee hyperextension to create stability which has caused another condition – infrapatellar fat pad syndrome. It is also known as Hoffa’s pad impingement syndrome which is the topic of this post. Read on to learn more about infrapatellar fat pad syndrome. Let’s start with anatomy.
The knee joint
The knee is the largest joint in the body. The knee is made up primarily by the tibiofemoral joint and patellofemoral joint. The tibiofemoral joint is what most of us think of as the knee. It is the joint made between the bottom of the femur (the thigh bone) and the top of the tibia (the shin bone). The patellofemoral joint is the joint made between the femur and the patella (the kneecap).
The quadriceps
The quadriceps are a group of 4 muscles on the front of the thigh. These are very large powerful muscles that activate to straighten the knee. They are extremely important in performing everyday activities such as squatting, walking, running, jumping, kicking, and many others. The 4 quadriceps muscles come together towards the bottom of the femur (the thigh bone) and form a common tendon called the quadriceps tendon. A tendon connects muscle to bone. The quadriceps tendon then attaches to the patella and the patella connects to the tibia (the shin bone) through the patellar tendon (which is actually a ligament). The patella acts as a pulley when the quadriceps contract to straighten the knee. This is known as the extensor mechanism.
The infrapatellar fat pad
There are 3 fat pads in the front of the knee. The one that tends to get in trouble the most is the infrapatellar fat pad (IFP) which is also known as Hoffa’s fat pad. This fat pad lies in between the bottom of the patella and the top of the shin bone. It is located under the patellar tendon. The IFP functions to distribute pressure across the patellofemoral joint, protect the knee from mechanical damage, and stabilize the patella.
Infrapatellar fat pad syndrome
Infrapatellar fat pad syndrome occurs when the fat pad is impinged or pinched between the patella and the femur or between the femur and the tibia. The fat pad is highly vascularized and has a good nerve supply which means that impingement can be very painful. There are several different ways that this impingement can occur. These include:
- Direct blow to the knee
- Injury with anterior cruxiate ligament (ACL tear) or patellar dislocation
- Result of knee surgery
- Twisting injury at the knee
- Overuse that causes repeated micro trauma
- This can occur from sports or other activities that cause the knee to hyperextend repetitively.
- This is the most common cause.
- Can cause the tissue of the IFP to thicken and become more fibrotic.
When the IFP becomes irritated it will cause mechanical changes in the extensor mechanism. This results in pain and limitation when trying to straighten the knee.
Infrapatellar fat pad syndrome is an uncommon primary diagnosis but is a more common secondary diagnosis. This means that it more often occurs with other pathologies including meniscal injuries, patella tendinopathy, knee osteoarthritis, and ligamentous injuries. However, in general, fat pad syndrome is under-diagnosed meaning that it is often overlooked.
Symptoms of fat pad syndrome
There are several symptoms associated with infrapatellar fat pad syndrome. These include:
- Swelling in the front of the knee below the patella
- Pain in the knee – usually described as burning or aching
- Pain when trying to straighten the knee
- Decreased ability to straighten the knee
- Pain when the knee is bent for a prolonged period
- Pain with long walks and prolonged standing
- Pain with standing in flat shoes
- Pain going up and down stairs
Risk factors
There are several risk factors associated with infrapatellar fat pat syndrome. These include
- Jumping sports or activities
- Knee osteoarthritis
- Being a young female
- Hypermobility or ability to hyperextend knees
- Tight quadriceps (muscle on the front of the thigh)
- IT band tightness
- Sports or activities in which the knee is repeatedly hyperextended. These include:
- Dancing
- Running
- Cycling
- Jumping sports
Who should I see?
- Physical therapy – This would be my first stop. Physical therapy can help decrease pain and swelling in the knee. Also, your physical therapist will slowly introduce strengthening and stretching exercises for your hip and knee. Your PT will aid you in learning how to recognize when your knee is hyperextended and how to control the position of the knee.
- Orthopedic or sports medicine physician – An orthopedist might be necessary if your condition is not responding to physical therapy. Your physician can prescribe medication, give an injection, or order imaging if needed. Surgery is an option if the knee does not respond to conservative treatment.
What can I do?
- Relative rest – Resting the area to decrease further pain and damage from occurring is one of the best ways to decrease the pain and swelling. Basically, stay away from the activities that are causing pain for a period of time. You can perform non-irritating activities such as swimming or walking to maintain cardiovascular and muscle strength. Return to your sport slowly once the pain has subsided.
- Knee posture – Usually when I talk about posture, it is the position of the spine, shoulders, or head. This time I am talking about the knees. Infrapatellar fat pat syndrome occurs with repetitive hyperextension of the knees. In order to decrease the pain and prevent it from returning, the person will need to train themselves from hyperextending. For sports and athletic activities, it might be that you need to train yourself to bend the knees when landing a jump. If you tend to lock your knees out and stand in knee hyperextension, then learn to stand with what I call a soft knee. A soft knee is a knee that is not really bent but neither is it locked in extension.
- Ice – Ice can help decrease pain and swelling in the tendon. Ice the painful area for 15 to 20 minutes at a time. I would recommend using an ice pack several times per day if the pain is constant or is preventing you from participating in an activity. Ice immediately after activity.
- Soft tissue mobilization – Soft tissue mobilization helps release the quadriceps and decrease the stress on the knee. Roll on a massage ball or trigger point roller on the painful area on or around the quadriceps. Spend a good 3 to 5 minutes rolling. Do not roll so hard that you bruise the area, but it should be a pretty painful sensation. Roll out the area no more than a few times a week. See the video below.
- Stretching – The hip flexor and quadriceps are typically tight with infrapatellar fat pad syndrome. Decreasing tightness in the quadriceps can decrease the pull on the quadriceps and stress on the fat pad. See the video below for quadricep, hamstring, hip flexor, and calf stretching.
- Strengthen the muscles around the hip and knee– It is important to strengthen the muscles around the hip and knee. This includes your gluteal muscles, quadriceps, and the hamstrings. It is also important to strengthen your core muscles. All these muscles will help take some of the load off of the extensor mechanism. Using loop resistance bands , resistance bands and ankle weights can increase strength and difficulty of the exercises. See the videos below.
- Shoewear – While you are actively having pain in the knee, avoid shoes that are very flat. These would include ballet flats, sandals, and flip flops. Wear shoes with some type of elevation. This can include supportive running or athletic shoes.
- Knee taping – Using kinesiology tape to help decrease the stress on the fat pad is also a good way to decrease pain. See the video below for how to tape the knee.
In review
- There are 3 fat pads in the front of the knee.
- The one that tends to get in trouble the most is the infrapatellar fat pad (IFP) which is also known as Hoffa’s fat pad.
- Infrapatellar fat pad syndrome occurs when the fat pad is impinged or pinched between the patella and the femur or between the femur and the tibia.
- The most common cause is repetitive hyperextension of the knees during sports or other activities.
- Symptoms include pain in the front of the knee and difficulty straightening the knee.
- Physical therapy has an excellent success rate at treating this condition.
- An orthopedic or sports medicine physician would be needed if the knee is not responding to physical therapy.
- There are several things that you can do at home.
- Relative rest
- Don’t hyperextend your knees
- Ice
- Soft tissue mobilization
- Stretching
- Strengthening
- Shoewear
- Taping
As always, If you have questions about the content of this post or any other musculoskeletal questions, please e-mail me.
Additional resources
https://www.physio-pedia.com/Fat_Pad_Syndrome
https://www.ncbi.nlm.nih.gov/books/NBK589637/