Have you been experiencing a sharp or chronic pain just under the kneecap that often gets worse on standing for too long or hyperextending the knee? In medical terms, that’s also called an anterior knee pain. Well, sometimes it gets difficult to diagnose the cause behind this pain. It is not always the bones, cartilage, capsule or the synovial fluid that’s causing the pain. It may be triggered due to a fat pad impingement. As its name sounds, it is a pad of fat that gets impinged upon or affected in some way or the other and hence the pain! It is also known as Hoffa Syndrome. In Fat Pad Impingement, one of three pads of fatty soft tissue that lies under the kneecap (patella) gets affected and leads to the pain at the front of the knee.
What’s Hoffa’s fat pad?
The Hoffa’s fat pad acts as a protective cushion, which separates the kneecap from the shin and thigh bones, protecting the condyle of the femur from being hit by the patella in the case of a direct blow to the kneecap. The fat pad contains several nerves and thus when it is damaged, one feels the pinch. A person’s hip and/or knee alignment can cause the fat pad to become irritated and impinged.
Cause of Impingement
Some of the most common causes of Fat pad Impingement are as follows:
- Tight quadriceps
- Anterior pelvic tilt
- A severe Impact to the front of the knee
- Scarring and successive hardening of the fat pad
- History of osteoarthritis that affected the knee
- Extreme extension of the knee also known as ‘Genu Recurvatum
The Vulnerable ones
Fat Pad Impingement is commonly seen among people who engage in sports or activities, in which a forceful blow to the knee is highly likely, such as hockey, martial arts, football, soccer, and rugby. People, who have suffered from an anterior cruciate ligament (ACL) injury, are also at risk. An ACL injury decreases the stability of the knee, which makes the fat pad more prone to impingement. Hyperextension in the knee in patient with hypertension syndrome is also vulnerability. People with Iliotibial Band Syndrome (overuse injury of the connective tissues that are located on the outer thigh and knee) may also get affected. Runners with flat feet (also known as excessive pronation) or with muscle weakness and imbalance around their hip muscles are also at risk.
Symptoms
- Pain when extending the knee
- Pain after walking with high heels on
- Pain after walking, kicking, climbing stairs or squatting for long
- Knee Pain especially on the front of the Knee, just below the Kneecap (Infrapatella Pain)
- Inflammation and swelling on the kneecap and below the kneecap
- Pain after standing on hyperextended knees for extended periods
Diagnosis
- A detailed history regarding the onset, site and type of pain will surely help.
- Hoffa’s Test that involves contracting the quadriceps muscles and then moving the kneecap is used for diagnosis.
- MRI (Magnetic resonance imaging) can be done to check for fat pad impingement.
Treatment
- Use cold therapy or apply ice to the knee to reduce knee pain and inflammation. Application of the ice should not be directly on the skin to avoid skin burns. Instead, one should wrap the ice in a tea towel or use recommended knee wraps.
- Rest and avoid activities that may strain the knees.
- A physiotherapist may also use electrotherapy such as TENS and ultrasound to treat fat pad impingement.
- A patient should also carry out exercises that strengthen the knee muscles. The exercises should not put excessive strain on the knees. These should be prescribed by a physiotherapist.
- Taking anti-inflammatory medications prescribed by the doctor.
- Taping the kneecap is also an effective treatment for treating the condition since it helps create more space for the fat pad, therefore minimising the stress on it.
- In some scenarios, a steroid injection to the knee may be considered to help reduce inflammation and pain.
- In some exceptional cases such as Lipoma Arborescence in which conservative methods fail surgery may be advised. Surgery may involve complete or partial removal of the fat pad.
Prevention
The most appropriate way of preventing cases of fat pad impingement is through stretching and strengthening the muscles around the hip, ankle and knee area. The physiotherapist will provide the appropriate exercises needed to stretch and strengthen these muscles. People should limit or avoid walking in high heels to prevent further injury to the fat pad.
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