Fat Pad Impingement

Articular (relating to a joint) fat pads are accumulations of fatty soft tissue that occupy space and irregularities within a joint. They act as flexible protective cushions that accommodate the changing shape of the joint during movement ⁽³⁾.

The infrapatellar fat pad, also known as the Hoffa’s fat pad, sits behind and just below the kneecap between the shin (tibia) and thigh (femur) bones. The location is thought to expose the fat pad, making it more suspectable to injury, especially during the end of range knee extension (straightening) ⁽¹⁾.

If pain is present at the front of the knee, around the bottom of the kneecap and is worse when the knee is fully extended, the infrapatellar fat pad might be the source of discomfort.

The movement of knee extension (in symptomatic cases) causes the fat pad to become impinged, hence the reason why some clinicians will refer to this condition as infrapatellar (beneath the kneecap) fat pad impingement syndrome. The fat pad also has a rich supply of nerves which contribute to the discomfort levels often experienced with this condition ⁽²⁾.

Most commonly this condition is thought to develop gradually over time following repetitive overextension of the knee. Some individuals may be more susceptible to developing this injury if they have perpetuity towards knee hyperextensions, such as those who partake in jumping sports and those with ligament and joint laxity conditions such as hypermobility syndrome. In other instances, this condition can start following a direct blow to the knee ^{(1, 3)}.

Prevalence is not fully understood however, studies reported isolated fat pad injuries in 1% of people suffering from anterior knee pain ⁽¹⁾, which makes it a very rare condition.

Musculoskeletal physiotherapists and other appropriately qualified healthcare professionals can provide you with a diagnosis by obtaining a detailed history of your symptoms. A series of physical tests might be performed as part of your assessment to rule out other potentially involved structures and gain a greater understanding of your physical abilities to help facilitate an accurate working diagnosis.

Your treating clinician will want to know how your condition affects you day-to-day so that treatment can be tailored to your needs and personalised goals can be established. Intermittent reassessment will ascertain if you are making progress towards your goals and will allow appropriate adjustments to your treatment to be made. Imaging studies like MRIs or ultrasound scans are usually not required to achieve a working diagnosis, but in unusual presentations, they may be warranted.

Your treating clinician will help you understand your condition so that you are able to help support your recovery. Initial treatment should focus on reducing pain and inflammation. Dependent on the severity and physical limitations, it is recommended that you limit or avoid aggravating tasks. Some examples include reducing prolonged periods of standing, remaining vigilant for not over-extending the knee and avoiding sports that exacerbate symptoms. If your symptoms do not improve to the point where you feel you are able to self-manage then it would be encouraged to seek further input from an appropriately qualified musculoskeletal specialist. We encourage the utilisation of methods highlighted in this PEACE & LOVE acronym which can be implemented for early recovery but should always be guided by an appropriately qualified musculoskeletal specialist ⁽⁸⁾.

For patients wanting to achieve a higher level of function or return to sport, we would encourage a consultation with a musculoskeletal physiotherapist as you will likely require further progression beyond the advanced rehabilitation stage. Before returning to the sport, a rehabilitation programme should incorporate plyometric based exercises which might include things like bounding, quick changes in direction of movement and sprinting exercises.

Corticosteroid injection may provide temporary pain relief, but this should only be considered as a last resort if appropriate and progressive conservative management has failed. Even if conservative management does not achieve a 100% improvement, careful consideration is heavily encouraged as in some cases injections cause more harm than good. Surgery may be recommended but this should be the last option if all other treatment attempts have been exhausted ⁽⁵⁾.