Patellar tendon-lateral femoral condyle friction syndrome

Dr Henry Knipe and Dr Andrew Dixon et al.

Patellar tendon-lateral femoral condyle friction syndrome, also known as Hoffa fat pad impingement syndrome, is a common cause of anterior knee pain in active individuals. It is thought to be due to patellar maltracking or imbalance of the forces between medial and lateral vastus muscles causing impingement of the superolateral aspect of Hoffa fat pad between the inferior patella and the lateral femoral condyle.

Clinical presentation

Patients present with anterior knee pain exacerbated by hyperextension, and with point tenderness at the inferior pole of the patella. The fat pad is thickened which may make palpating the patella difficult 1.

Radiographic features

It is usually occult on plain radiographs and CT.


Focal area of high T2 signal (edema) at the inferolateral aspect of the patellofemoral joint, within the superolateral portion of the infrapatellar fat pad. A cystic lesion can sometimes be found between the lateral femoral condyle and the lateral retinaculum. Associated findings include lateral patellar subluxation and patella alta (Insall-Salvati ratio greater than 1.2) which are found in around 90% of cases 1,2.

Knee pathology

The knee is a complex synovial joint that can be affected by a range of pathologies:

Article information

rID: 10353
Tag: knee, refs
Synonyms or Alternate Spellings:
  • Hoffa's fat pad impingement syndrome
  • Hoffa fat pad impingement syndrome
  • Hoffa's disease

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Cases and figures

  • Case 1: PD FS
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  • Case 1: T2 FS
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  • Case 2: PD FS
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  • Case 2: PD FS
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  • Case 3
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  • Case 4
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  • Hoffa fat edema i...
    Case 5
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