What is Hoffa's fat pad impingement?

What the fat pad is and does

The infrapatellar fat pad, named after the surgeon Albert Hoffa, fills the space behind the patellar tendon and below the kneecap. It cushions the front of the joint, changes shape as the knee bends and straightens, and helps spread joint fluid. It also has a rich supply of nerves and blood vessels, which is why irritation hurts and swells.

How impingement happens

• A direct blow to the front of the knee, for example a fall on to a hard floor
• Repeated forceful straightening or hyperextension, in kicking sports, dance or gymnastics
• Habitual standing with the knees locked back, often in people with hypermobile joints
• Scarring after knee surgery, especially arthroscopy or ACL reconstruction
• Inflammation from other knee problems, such as arthritis

How it is diagnosed

Diagnosis is mainly clinical. The surgeon presses either side of the patellar tendon while straightening the knee, which typically reproduces the pain. An MRI can show swelling or scarring in the fat pad and, importantly, checks for other causes of pain at the front of the knee, such as patellar tendinopathy, a meniscus tear or cartilage damage. X-rays are used to check bone alignment and arthritis.

Treatment in brief

Most people improve with load modification, avoiding locked-knee standing, ice during flares, taping and a physiotherapy programme that strengthens the thigh and hip and improves control of straightening. A targeted injection is sometimes considered for stubborn cases. Arthroscopic trimming of scarred or enlarged fat pad tissue is reserved for symptoms that persist despite good rehabilitation.

At Aman Hospital in Doha, Dr. Gelber explains the findings and builds the plan around your work and sport.