Is Superolateral Hoffa Fat Pad Edema a Consequence of Impingement between Lateral Femoral Condyle and Patellar Ligament?

Abstract

A high-riding patella, a short distance between the patellar ligament and the lateral trochlear facet, and an increased distance from the tibial tubercle to the trochlear groove are associated with superolateral Hoffa fat pad edema at MR imaging. These results are suggestive of impingement between the lateral femoral condyle and the posterior aspect of the patellar ligament in these patients.

Magnetic Resonance Imaging of the Extensor Mechanism

“…Localized edema in the superolateral IPFP has been described in the setting of lateral patellofemoral friction syndrome, or patellar maltracking, termed patellar tendon-lateral femoral condyle friction syndrome. 65,66 The mechanism is thought to relate to impingement of the superolateral aspect of the fat pad between the lateral femoral condyle and the patellar tendon. 67 MR findings show abnormal signal consistent with edema in the superolateral IPFP, as well as an association with a high-riding patella, increased TT-TG distance, and diminished patellar tendontrochlea distance.…”

“…23). 65 Young patients are most prone to superolateral Hoffa fat pad edema and such edema may be asymptomatic. 68 Anterolateral pain has also been found most often to be associated with tendinosis of the lateral patellar tendon in the setting of superolateral IPFP impingement.…”

MRI of lower extremity impingement and friction syndromes in children

“…First described in 2001 using MRI (25), patellar tendon-lateral femoral condyle friction syndrome is characterized by an impingement between the lateral femoral condyle and posterior aspect of the patellar tendon, resulting in superolateral infrapatellar (Hoffa) fat pad edema on MRI (26). This condition is associated with focal tendonopathy at the lateral aspect of the patellar tendon, a high-riding patella (Fig.…”

“…This condition is associated with focal tendonopathy at the lateral aspect of the patellar tendon, a high-riding patella (Fig. 7); other patellofemoral malalignment/ maltracking features such as a short distance between the patellar ligament and lateral femoral condyle; and an increased distance from the tibial tubercle to the trochlear groove (26). In other words, when edema at the superolateral aspect of the infrapatellar fat pad is identified using MRI, patellofemoral malalignment and maltracking need to be scrutinized (27,28).…”

MR Imaging of Extrasynovial Inflammation and Impingement About the Knee

“…26,27 The edema described may be the result of impingement between the lateral femoral condyle and the posterior aspect of the patellar tendon. 22,27,28 The IFP contains adipocytes, macrophages, lymphocytes, and granulocytes as well as nociceptive nerve fibers that could in part be responsible for anterior pain. 15,29 It plays a role in stabilizing the patella in extremes of flexion and extension.…”