Hoffa’s syndrome is a condition where the fat pad sitting just behind your kneecap becomes pinched, swollen, and painful. This pad of fatty tissue, called the infrapatellar fat pad, fills the space below the kneecap and around the patellar tendon. When it gets repeatedly trapped between the bones of the knee joint, it becomes inflamed and can cause persistent anterior knee pain that’s often mistaken for other conditions like patellar tendonitis.
What the Fat Pad Actually Does
The infrapatellar fat pad is present in every knee. It has a central body with extensions on the inner and outer sides, and it acts as a cushion and shock absorber between the kneecap, the shinbone, and the patellar tendon. The fat pad is one of the most nerve-rich structures in the knee, which is why problems with it can produce intense pain. It also plays a role in joint lubrication and may help with blood supply to nearby structures, including a healing anterior cruciate ligament.
How the Fat Pad Gets Injured
Hoffa’s syndrome develops when the fat pad becomes trapped, or “impinged,” between the kneecap and the thighbone during movement. This can happen after a direct blow to the front of the knee, from hyperextending the knee, or through repetitive strain from activities that involve frequent straightening of the leg. Once the fat pad is pinched, it swells. A swollen fat pad takes up more space in the joint, which makes it even easier to pinch again, creating a cycle of repeated impingement and worsening inflammation.
Over time, chronic impingement can cause the fat pad to become fibrotic, meaning the soft fatty tissue is replaced by tougher scar tissue. This makes the pad stiffer and larger, further increasing the likelihood of it getting caught in the joint. People who are more prone to the condition include those with a history of knee surgery, athletes in sports requiring repetitive jumping or kicking, and anyone whose knee alignment or kneecap position puts extra pressure on the front of the joint.
What Hoffa’s Syndrome Feels Like
The hallmark symptom is a burning or aching pain at the front of the knee, felt deep to and on either side of the patellar tendon, near the bottom of the kneecap. The pain typically gets worse when you fully straighten your knee, actively extend your leg (like kicking), or sit for long periods with your knee bent. Tightening your thigh muscle with the knee straight can also reproduce the pain.
All patients experience some degree of restricted range of motion, and in severe cases, the knee can lock at around 20 degrees of flexion. The fat pad itself may feel swollen, firm, or tender when pressed. Some people also notice decreased kneecap mobility, where the kneecap feels “stuck” and doesn’t glide as freely as it should.
How It Differs From Patellar Tendonitis
Because the pain sits in the same general area, Hoffa’s syndrome is frequently confused with patellar tendonitis. The key difference is where the pain originates and what triggers it. Patellar tendonitis typically produces pain directly on the tendon itself, worsened by loading activities like squatting or jumping. Hoffa’s syndrome pain is located deeper and to the sides of the tendon, and it’s most reliably provoked by full knee extension rather than loaded flexion. The physical exam also distinguishes the two: with patellar tendonitis, tenderness is on the tendon; with Hoffa’s syndrome, the tenderness is beside and behind it.
Getting a Diagnosis
A clinician can perform the Hoffa test in the office. You sit with your knee bent to about 30 degrees while the examiner presses firmly just below your kneecap, to the side of the patellar tendon. While maintaining that pressure, your knee is slowly straightened. If this reproduces your pain, the test is positive. The test is then repeated on the other side of the tendon.
MRI is the preferred imaging tool for confirming the diagnosis. On an MRI, a swollen fat pad shows up as bright areas on fluid-sensitive sequences, indicating edema or bleeding within the tissue. Chronic cases may show bands of fibrosis running through the fat pad. However, MRI findings need to be interpreted alongside your symptoms, because fat pad edema can sometimes appear on scans of people with no knee pain at all.
In some cases, a diagnostic injection of local anesthetic into the fat pad is used. If the injection temporarily eliminates the pain, it supports the diagnosis.
Conservative Treatment
Non-surgical management is the first approach. The core of treatment is exercise therapy, which remains the gold standard for anterior knee pain. Strengthening the quadriceps (particularly the inner portion called the vastus medialis oblique), glutes, and hip stabilizers helps improve how the kneecap tracks and reduces pressure on the fat pad. Activity modification matters too: avoiding prolonged periods of full knee extension or sustained deep flexion can prevent repeated impingement while the inflammation settles.
Taping techniques like McConnell taping can provide short-term pain relief by adjusting the position and movement of the kneecap, limiting its side-to-side shift and tilt. Guidelines recommend using taping as a supplement to exercise therapy rather than as a standalone treatment. Patellar straps and braces are another low-cost, low-risk option that some people find helpful during activity.
Corticosteroid injections into the fat pad are sometimes offered, but the evidence for their effectiveness is limited. A randomized clinical trial of 60 patients found that glucocorticoid injections into the fat pad did not produce a statistically significant reduction in pain scores compared to placebo. Both groups improved, but there was no meaningful difference between them.
When Surgery Is Considered
Surgery becomes an option when symptoms persist despite at least three months of conservative treatment. The procedure is done arthroscopically, meaning through small incisions using a camera and surgical instruments. During the operation, the surgeon examines the fat pad and removes the portion that is being impinged between the kneecap and thighbone.
There are two main approaches. In a partial resection, only the impinged section of the fat pad is removed. In a subtotal resection, roughly two-thirds of the fat pad is removed while preserving the base. After the tissue is trimmed, the surgeon moves the knee through its full range of motion to confirm that no remaining tissue is getting caught.
Recovery After Surgery
Recovery from arthroscopic fat pad debridement follows a relatively quick timeline compared to many other knee surgeries. In the first two weeks, you can bear weight on the leg as tolerated with no brace required. The focus during this phase is on regaining full range of motion through exercises like heel slides, straight leg raises, and quad and hamstring activation. Patellar mobilization, where you gently push the kneecap in different directions, begins immediately.
You can typically return to a desk job or school within three to four days. Formal physical therapy starts 7 to 10 days after surgery. By weeks two through four, you progress to full weight bearing with full range of motion, and can begin cycling, using an elliptical, and running as tolerated. Sport-specific exercises are introduced during this phase as well.
From weeks four through twelve, the focus shifts to sport-specific training and building a maintenance program for core, glute, hip, and balance work. Most people should expect to avoid activities that increase knee pain or swelling, like prolonged standing, for the first 7 to 10 days. Long periods of sitting without elevating the leg should be avoided for two weeks. Pain medication is generally only needed for 2 to 5 days after the procedure.