|Hoffa's Posterior Fat Pad Syndrome|
| The diagram of the right knee on the previous page shows two arrows pointing to the regions where the fat pad is commonly trapped. Superiorly the fat pad is trapped between patella and trochlea. Posteriorly it is trapped between the femoral and tibial condyle. (Magi M, Branca A, Bucca C, Langerame V. Hoffa disease. Ital J Orthop Traumatol. 1991 Jun;17(2):211-6.) The consequences of this biomechanical problem are simple to understand. Interposition of parts of the fat pad between the articular hyaline cartilage surfaces leads to first fibrosis (hardening) of the interposed fat pad. Then increasing degrees of degenerate change of the surfaces where the fat pad is interposed (chondromalacia). The video loop on the left shows a tongue of fat pad being removed arthroscopically using a magnified image. The minor damage to the surface of the lateral aspect of the medial femoral condyle can be made out.WIthout treatment like this the minor degenerate change can progress to the end stage of osteoarthritis. This progression of degenerate change leading to arthritis takes time and depends on the size of the fragment causing impingment, the loads being applied and the frequency of application of these loads. The analogy would be a stone in the shoe. The heavier the person the greater the pain and damage. The smaller the stone the greater the pain and damage. The longer the person walks on the stone before removing it the greater damage to the skin of the heel. These are simple biomechanical principles.|
The condition can be treated using simple biomechanical principles also. The effectiveness of treatment for infrapatella plica syndrome depends on how much damage has been caused to the hyaline cartilage of the condyles that are being impinged upon by the fat pad. Early on the fat pad is soft and the consequences of impingment are minor. Later the fat pad itself undergoes fibrosis and becomes hard and then the impingement changes as a result of cyclic loading are far from minor. The hyaline cartilage undergoes degenerate change and arthritis occurs.
One early presentation, where the changes in the fat pad are minimal and there is no damage to the articular surfaces conservative measures are frequently helpful. About 33% of patients can be treated with simple techniques like patella taping, analgesia and physiotherapy. Depending on the direction taping was found to be useful a patellofemoral brace may then be of some comfort during sporting activities. As the condition progresses about 33% of patients find that though there is pain releif with conservative measures when these are not employed the pain returns. These patients should consider the option of arthroscopic (keyhole) surgery. Patients with symptoms that have gone on progressivly for more than 6 weeks despite trying conservative measures should be consulting you for a referral to a Consultant in Orthopaedics and Trauma with an interest in knee surgery.