Hoffa's Fat Pad Impingement

Knee Osteoarthritis

What is Hoffa's Fat Pad Impingement?

Hoffa's fat pad impingement, also known as Hoffa's syndrome, is a condition that causes pain in the front of the knee, below the kneecap. It occurs when the infrapatellar fat pad, a soft tissue cushion located behind and below the kneecap, becomes inflamed or pinched between the kneecap and the thighbone. This can happen due to repetitive overuse, direct trauma, or underlying knee conditions. The fat pad can also become pinched when adverse knee mechanics result in uneven forces on the kneecap, as it rides in the groove in the front of the thigh bone.

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Who is at Risk for Hoffa's Fat Pad Impingement?

Hoffa's fat pad impingement is most common in individuals who participate in sports or activities that involve repetitive stress on the knee joint, such as running, jumping, or squatting. It can also affect individuals with patellofemoral instability, a condition where the kneecap tracks abnormally, increasing pressure on the fat pad. This is more common in young, active women, where the kneecap tends to drift to the outer side of the groove that it runs in, rather than sitting centrally. This results in an uneven distribution of forces, favouring the outer side i.e. the left side of the left knee. This can result in pinching of the fat pad and pain.

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What are the Main Symptoms of Hoffa's Fat Pad Impingement?

The primary symptom of Hoffa's fat pad impingement is pain in the front of the knee, typically located below the kneecap and extending to the sides. The pain is often aggravated by activities that involve deep knee flexion, such as squatting, lunging, running downhill, or using stairs. Other symptoms may include:

  • Swelling and tenderness around the kneecap

  • A burning or aching sensation in the knee

  • Difficulty straightening or bending the knee fully

  • Clicking or popping sounds in the knee, particularly when walking upstairs

  • Discomfort when sitting for long periods.

How is Hoffa's Fat Pad Impingement Diagnosed?

A thorough medical history and physical examination are crucial for diagnosing Hoffa's fat pad impingement. The doctor will assess the patient's symptoms, range of motion, and tenderness around the knee, particularly in the area beneath the knee cap, on either side of the patella tendon. Imaging tests, such as ultrasound or MRIs, may be used to rule out other potential causes of knee pain and confirm the presence of inflammation or swelling in the infrapatellar fat pad.

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How is Hoffa's Fat Pad Impingement Treated?

Treatment for Hoffa's fat pad impingement typically involves conservative measures, such as:

  • Rest:

    Avoiding activities that aggravate the pain, such as deep knee flexion or high-impact sports
  • Ice:

    Applying ice packs to the affected area for 10-15 minutes at a time, to reduce inflammation
  • Taping or Bracing:

    Wearing a knee brace or tape can help kneecap tracking for short periods, resulting in an improvement in pain during activity
  • Stretching and strengthening exercises:

    Gradually introducing exercises to improve flexibility and strength in the quadriceps, hamstrings, and calf muscles

In some cases, additional treatment options may be considered, such as corticosteroid injections.

At The Joint Injection Clinic, these injections are performed after a thorough consent process, whereby the risk and benefits of the procedure are discussed in detail with your doctor.  The experienced medical doctor will then place you in a lying position, face up.  The skin is cleaned using a cleaning solution to ensure that the procedure is performed under sterile conditions.  The combined local anaesthetic and steroid is injected from the skin to the fat pad under ultrasound guidance. 

The injection itself is normally completed within 30 seconds, after which a plaster is applied and post-injection advice is given.  The patient is advised to look out for any signs of infection, specifically to check whether the local area becomes red, hot, tender, swollen or if they develop a fever.  If this occurs then the patient is asked to contact the clinic immediately at which time a formal reassessment will occur and if needed oral antibiotics can be prescribed.  The patient is also warned that following this particular injection they may notice a short-term worsening or flare in their symptoms after the local anaesthetic has worn off (4-5 hours).  This may last for 3-5 days and the patient is advised to consider icing of the area using an ice pack for 10-15 minutes every hour as required.

Surgery is rarely considered for Hoffa's fat pad impingement and is typically only recommended if conservative measures have failed to provide relief.

If you experience persistent pain or discomfort in the front of your knee, it is essential to consult a healthcare professional for proper diagnosis and treatment. Early intervention can help prevent further injury and improve overall knee function.

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