1905 Journal of the American Medical Association (JAMA)  
When it is not abnormally enlarged, this pad of fat can hardly be felt, and there is usually a slight hollow on both sides of the patellar ligament. After an injury, however, such as a bruise or strain, there may be a marked increase in the size of the fatty mass, possibly by the organizing of a blood-clot,' or perhaps by a direct growth of the fat-tissue itself from the stimulus of the traumatism. This hypertrophy may not disappear, and may even increase gradually until flexion and extension
more » ... ion and extension of the leg are materially limited by the mechanical interference of this dense wedge of tissue. If the leg bo forcibly flexed, the patellar tendon and its lateral ligaments or expansions are made tense and the pad of fat is compressed against the tibia and the condyles and forced out on both sides of the tendon, bulging outward under the more yielding lateral ligaments until the limit of compression is reached. If the leg be extended the notch between femur and tibia is narrowed and the pad is again compressed, though not so much as in flexion.
doi:10.1001/jama.1905.52510010040002 fatcat:cdb4kepoxjhtrb2thbno36oike