Keywords:
Oedema, Education, MR, Musculoskeletal soft tissue
Authors:
J. Araújo, S. Magalhães, I. Ferreira, J. Pires, R. Maia, M. Ribeiro; porto/PT
DOI:
10.1594/essr2015/P-0045
Background
HOFFA´S FAT PAD ANATOMY (Fig.1)
- The infrapatellar fat pad Hoffa is a structure located in the space between the back side of the pattelar ligament and the real capsule.
- It is routinely visualized on the magnetic resonance images of the knee.
- There are other fat pads located between the sinovial and the joint capsule of the knee joint that are intracapsular but extrasynovial structures.
- Hoffa's fat lies behind the patella ligament and extends slightly superior and posteriorly.
It overlaps the inferior articular surface of the patella,
the anterior aspect of the femoral condyles,
the intercondylar notch and the anterior cruciate ligament.
- The infrapatellar plica has a narrow femoral origin in the anterior part of the interchondylar notch and widens as it descends anteriorly and inferiorly throught the infrapatellar fat pad to attach distaly to the inferior pole of the patella. (Fig.2)
- Here are some aspects of the Hoffa's fat pad neurovascular supply:
- Vascular supply (superior and inferior genicular arteries) is related to the role played by the synovium in the production of synovial fluid and removal of debris.
- The periphery is highly vascularised while more centrally,
closer to the patellar ligament,
the blood vessels are less plentiful.
- It is inervated by branches of the femoral,
common peroneal and saphenous nerves.
HOFF'S FAT PAD- symptomes and diagnosis.
- Hoff's fat pad disease is characterized by knee pain,
mostly under the patella.
Acute cases are generally post-traumatic.
The clinical picture consists mainly of anterior pain and functional impairment,
mimicking a ligament injury.
- At clinical examination,
Hoffa's sign is difficult to observe but can be highly specific.
Extending a bent knee putting pressure on the patellar tendon margins elicits a strong pain,
an antalgic block and a defensive behavior of the patient.
- MRI clearly depicts Hoffa's infrapatellar fat pad and its findings may suggest the frequently ignored diagnosis of Hoffa´s syndrome,
alone or associated with other local or systemic conditions.
- Abnormalities within it most commonly are consequences of trauma and degeneration,
but inflammatory and neoplastic diseases of the synovium can be confined to the fat pad.
The commonest traumatic lesions follow arthroscopy but intrinsic signal abnormalities can also be due to posterior and superior impingment sydromes and following patellar dislocation.
Infrapatellar plica sydrome may also be traumatic in aetiology.
- Abnormalities that are intrinsic to this fat pad include Hoffa disease,
intracapsular chondroma,
infrapatellar plica sydrome,
postarthroscopy and postsurgery fibrosis and cyclop lesion.
In addition,
the infrapatellar fat pad may be involved secondarily from extrinsic processes that include articular disorders,
such as joint effusion,
synovial abnormalities,
such as pigmented vilonodular,
lipoma arborescens,
reumatoid,
and extracapsular abnormalities,
such as Osgood-Schlatter disease,
Jumper´s Knee and Sinding-Larsen Johanssen syndrome.