Knee fat pad impingement also known as Hoffa syndrome, is one of the common causes of pain in front of the knee. As its name indicates, it occurs when a pad of fat (bursa) impinges between your patella and femoral condyle (femur or thigh bone). This happens when you fall onto your knees or you get a direct blow on your knee joint. If this is damaged, you will feel severe pain because of the rich nerve supply of this knee fat pad.
Fat pads are two wedge-shaped fatty structures present just behind your patella tendon and knee cap. They are also called Hoffa’s fat pads. They typically act as shock absorbers and execute the principles of biomechanics in their functioning. This flexible structure can change its shape to accommodate your joint movements. These fat pads are the most sensitive structures as they contain many sensory nerves.
This condition most commonly occurs in active individuals, such as dancers, or those that kneel as a part of their jobs, such as carpenters. Athletes, footballers, and runners are also prone to suffer from it due to vigorous movements at the knee joint. Individuals who are already suffering from any knee joint condition may also develop this condition.
Infrapatellar fat pad impingement is commonly confused with patellar tendonitis also known as jumper’s knee. The quadriceps muscle in the front of the thigh is attached to the patella by the patellar tendon, which extends to the shin bone(tibia). Injury to this tendon is known as jumper’s knee.
In this article, you will get to know the complete information regarding knee fad pad impingement syndrome and the steps you need to take to avoid this condition.
Causes of knee fat pad impingement
The fat pad is a mobile structure that usually moves out of your joint spaces as the knee bends. However, when you have swelling of your fat pad because of inflammation of the bursa (bursitis) or some other condition, you will feel difficulty in moving. And this impinges your fat pad between the thigh bone and patella during movements at the knee joint. Some of the causes of fat pad impingement are:
Knee hyperextension is one of the common causes(1). In hyperextension, your leg is straightened, and your patella and thigh bone are closely approximated. This decreases the space into which the fat pad can move and therefore the fat pad is prone to damage.
Physical trauma to the knee is likely to damage your fat pads. The fat pads are spongy structures and they can bear minor impacts. But in cases of severe impacts such as direct fall on the knee, this can lead to a meniscal tear and this can also tear your fat pads.
Hyperextension injury is seen in footballers. When the knee is in hyperextended condition, the stability of the joint is decreased. Any direct blow such as kicks to your knee in this condition of hyperextension can cause significant damage to your fat pads.
Ligamentous injuries especially the injury of your anterior cruciate ligament (ACL) is a potent cause of fat pad impingement. This ligament normally maintains the stability of your knee joint. When this ligament is damaged, inflammatory changes take place in your joint which increases the risk of fat pad damage.
Chronic inflammation of the knee joint due to some conditions such as arthritis also affects your fat pads. With these inflammatory conditions, there is swelling and it decreases the space into which the fat pads move during the knee movements. Your fat pads then undergo wear and tear and this increases the chances of fat pad impingement.
Signs & symptoms
Fat pad impingement is characterized by the following signs and symptoms. If you feel any of them, you need to seek your doctor’s advice to avoid any further complications of the condition.
Pain around your knee cap and around the sides of the patellar tendon is the first thing that you will experience if you have fat pad impingement. The pain is often difficult to localize and usually gradual in onset. Movements at the knee joint such as knee extension, or going upstairs become associated with the pain and may start getting worse.
If you feel swelling(2) along with outward tilting of your fat pad, chances are great that your fat pad is damaged. Due to inflammatory changes, swelling occurs in the fat pads behind the knee cap, and this swelling is indicated by the outward bulging of your knee cap.
As the fat pads function as shock absorbers, therefore, when they are damaged, you will not be able to perform movements at the knee joint. You will also feel pain during movements at your knee joint. In addition, you may hear grinding or creaking sounds as you move your joint.
Tenderness and redness around the knee cap. As your fat pad is inflamed, the ligaments of the knee joint are tensed and the blood vessels usually dilate in response to the inflammatory reaction. This results in tenderness and redness in the affected area.
Care & treatment for fat pad impingement
You can treat Hoffa’s syndrome at home using conventional therapies. However, the R.I.C.E. method is usually the first line of treatment.
Immediate treatment includes proper first aid. The first 48 to 72 hours of injury are critical. The R.I.C.E. method is one of the first-line treatments.
Stop doing any kind of movement for at least 2 days after injury because it can make the damage even worse and delay the recovery. Apply the ice pack for about 15 to 20 minutes after every 2 to 3 hours for 2 days.
Compression of the affected area is also effective in reducing swelling. You can use elastic bandages, casts, and splints for this purpose. The last one includes the elevation in which you need to raise the affected area above the heart level. This improves blood flow and has a pain relief effect.
Physical therapy for fad pad impingement
The first step in the recovery process is to modify the position and limit the activities in order to reduce pressure on the fat pads and thus reduce pain. Your physiotherapist will play an important role in this aspect and help to provide you with these specific recommendations that will have positive effects on your recovery process.
Some of these methods of physiotherapy (physio)are:
- Soft tissue treatment: Treatment of muscles surrounding the fat pad that is preventing normal joint movement because of their rigidity.
- Joint mobilization: Move the knee joint in an appropriate direction, in order to restore normal joint mobility. It also includes other areas that are also contributing to the abnormal knee joint movements.
- strengthening exercises: You should start a little bit of exercise at the knee joint to prevent muscle wasting.
Patella taping(3) is a short-term strategy that you can use to treat fat pad impingement as it reduces pressure on your fat pads. For this procedure, take 3 pieces of tape. The method is to tape the upper surface, inside and outside of your patella. This forms a V-shape and allows more space for the fat pad underneath, thus effective in reducing your pain.
Medical treatment for fat pad impingement
Medical treatment involves the use of painkillers such as nonsteroidal anti-inflammatory drugs(NSAIDs) like ibuprofen and diclofenac(4). They are used for such musculoskeletal conditions. These drugs are very effective in reducing inflammation and therefore reduce pain and swelling at your affected site. Some doctors also recommend the administration of steroid (corticosteroid) injection into your knee joint, if NSAIDs are unable to sufficiently reduce your pain.
Most patients with knee fat pad impingement do not require surgery. However, if the other treatments fail, then it can be the last option. There are various surgical procedures for the treatment of this condition such as resection of the infrapatellar fat pad(arthroscopy). X-rays and MRI(5) are done to determine the extent of the condition. Your orthopedic doctor usually performs a physical examination and joint manipulation prior to the surgery. A test, called Hoffa’s test, is to check whether you can fully extend your knee while the tendon is pressed. Patients with fat pad impingement will be unable to fully extend as this is a very painful procedure.
Electrotherapy such as ultrasound and transcutaneous electric nerve stimulation (TENS) is also effective to help reduce pain and inflammation, especially if you have swelling.
Preventive measures for pad pad impingement
Care should be taken to avoid this condition. Following are some of the measures that are helpful in preventing this condition
Regular exercise is the first thing that you can add to your lifestyle to prevent this condition(6). This increases the flexibility of muscles and also improves their strength. However, avoid vigorous exercise at the knee joint as it can excessively damage your fat pads.
Don’t extend your knee too much. Extend the knee only to the normal position as it provides enough space for the fat pads to escape. Hyperextension of the knee increases the risk of your fat pad impingement.
Avoid landing directly on your knees. Whenever you have to jump from some height, always land on your feet with your knees slightly flexed. Falling directly on the knees or on feet with extended knees causes significant damage to the knee joint and also alters joint stability.
Be cautious when participating in activities that put you in danger of falling or other injuries. When climbing or descending stairs, use handrails, prevent walking on slick surfaces, and inspect sports equipment before using it.
The fat pad impingement of the knee is a painful condition and you should avoid it, especially if you are an athlete or involved in various sports. Here in this article, we have explained to you the causes and symptoms indicating infrapatellar fat pad syndrome. You should also keep in mind the preventive measures to avoid this condition because if you are an athlete, it can adversely affect your career. Moreover, it also interferes with your daily routine activities. If you experience this condition, you should stop doing any kind of movement at the knee joint. If the symptoms worsen over time, then seek your orthopedic doctor’s advice immediately for proper medical care.
- van Raaij, T. M., & de Waal Malefijt, J. (2006). Anterior opening wedge osteotomy of the proximal tibia for anterior knee pain in idiopathic hyperextension knees. International Orthopaedics, 30(4), 248–252. https://doi.org/10.1007/s00264-005-0063-x
- Ghate, S. D., Deokar, B. N., Samant, A. V., & Kale, S. P. (2012). Tumor like swellings arising from Hoffa’s fat pad: A report of three patients. Indian Journal of Orthopaedics, 46(3), 364–368. https://doi.org/10.4103/0019-5413.96368
- Callaghan, M. J., Selfe, J., McHenry, A., & Oldham, J. A. (2008). Effects of patellar taping on knee joint proprioception in patients with patellofemoral pain syndrome. Manual Therapy, 13(3), 192–199. https://doi.org/10.1016/j.math.2006.11.004
- Genin, J., Faour, M., Ramkumar, P., Yakubek, G., Khlopas, A., Chughtai, M., King, D., & Mont, M. (2017). Infrapatellar Fat Pad Impingement: A Systematic Review. The Journal of Knee Surgery, 30(07), 639–646. https://doi.org/10.1055/s-0037-1604447
- Roemer, F. W., Jarraya, M., Felson, D. T., Hayashi, D., Crema, M. D., Loeuille, D., & Guermazi, A. (2016). Magnetic resonance imaging of Hoffa’s fat pad and relevance for osteoarthritis research: a narrative review. Osteoarthritis and Cartilage, 24(3), 383–397. https://doi.org/10.1016/j.joca.2015.09.018
- Dragoo, J. L., Johnson, C., & McConnell, J. (2012). Evaluation and Treatment of Disorders of the Infrapatellar Fat Pad. Sports Medicine, 42(1), 51–67. https://doi.org/10.2165/11595680-000000000-00000