Hoffa fat pad (infrapatellar fat pad) is a large intra-articular but extra-synovial adipose tissue mass occupying the anterior knee compartment between the patellar tendon anteriorly, the femoral condyles and tibial plateau posteriorly, and the inferior pole of the patella superiorly. It is richly innervated and highly vascularised, serving as a shock absorber, joint lubricant source, and mechanical buffer that fills the changing anterior knee space during flexion and extension.
Hoffa fat pad impingement (Hoffa syndrome) occurs when the fat pad is pinched between the femoral condyles and the patella during knee extension, producing anterior knee pain below and medial to the patella that is worse with forced extension. MRI demonstrates fat pad oedema and haemorrhage within the superolateral or medial aspect of the fat pad. Arthroscopic fat pad debridement is performed when conservative management fails. Over-resection of Hoffa fat pad during total knee arthroplasty reduces anterior soft tissue coverage and can impair patellar tendon blood supply.
Pinching of the infrapatellar fat pad between the femoral condyle and the patellar tendon during knee extension produces anterior knee pain and fat pad swelling visible as fullness below the patella, with MRI showing oedema in the superolateral fat pad, managed by physiotherapy avoiding hyperextension, corticosteroid injection, or arthroscopic partial fat pad resection.
Post-surgical scarring of Hoffa fat pad following ACL reconstruction, meniscal surgery, or anterior knee procedures produces cyclops lesion or fat pad fibrosis causing extension deficit and anterior knee pain requiring arthroscopic debridement.
