What is Fat Pad Impingement?
Sometimes after a forceful direct impact to the kneecap, the fat pad can become impinged (pinched) between the distal thigh bone ( femoral condyle) and the kneecap (patella).
As the fat pad is one of the most sensitive structures in the knee, this condition is known to be extremely painful. The knee pain is situated anteriorly on either side of the lower kneecap and is worsened by straightening (extension) of the knee joint. Hence the fat pad comes under constant irritation and may become significantly inflamed.
It is also termed Hoffa’s Syndrome.
Fat Pad of the Knee Joint
What Are the Symptoms of Fat Pad Impingement?
- Pain and/or swelling around the bottom and under the kneecap
- Patients may have a history of knee hyper-extension (called genu recurvatum)
- Positive Hoffa’s test (with the patient in lying with their knee bent, the examiner presses both thumbs along either side of the patellar tendon, just below the patella. The patient is then asked to straighten their leg. Pain and/or apprehension of the patient is considered a positive sign for fat pad impingement)
MRI Scan May Sometimes Show Fat Pad Inflammation
Treatment of Fat Pad Impingement
Treatment of this condition is normally by conservative methods such as:
- Rest and avoiding aggravating activities – stop running.
- Ice or cryotherapy to reduce pain and inflammation.
- Physiotherapy modalities such as ultrasound and TENS.
- Muscle strengthening exercises to maintain the strength and fitness of the surrounding muscle groups
- Taping the patella may help. One method involves taping the upper surface of the patella to allow more space for the structures beneath the lower surfaces i.e. the fat pad. This leads to less stress and impingement on the fat pad.
If conservative treatment does not work then surgery may be advised. This may involve the complete or partial removal of the fat pad itself.
Surgery for Fat Pad Impingement
This is done using key-hole arthroscopy surgery.
Two tiny holes on either side of the lower part of the kneecap allows the surgeon to visualise the problem using a camera system and a small motorised shaver to remove the impinging fat pad.
This is an example of a patient whom I treated recently. He experienced pain in the front of the knee for the past 3 to 4 months. The pain was brought on after running for about 10 minutes. He was able to complete his 1-hour run but would have pain and mild limp over the next 1 to 2 days. The problem worsened and he could no longer run for more than 10 minutes.
Clinical examination showed pain in the front of the knee at the level below and adjacent to the kneecap. The pain was made worse by straightening his knee.
This patient underwent arthroscopic excision of impinging fat pad. The pain went away immediately after the surgery.
I have a surgery video of the fat pad arthroscopic surgery but I cannot show it here due to the current Ministry of Health guidelines. If you wish to see it, please contact me. Hopefully the new updated guidelines will allow me to share the video with you on this website in the future.
