[Findings in sonography of the infrapatellar area of the knee joint].

In the infrapatellar region of the knee it is possible to demonstrate by sonography bursitis, tendinopathy, Hoffa's disease, and characteristic postoperative alterations. Bursitis is characterised by oval, echo-poor, badly limited structures in typical places. Typical of the tendinopathy of the patellar ligament is an enlargement of more than 8 mm.; calcifications can be seen in the region between 5 and 8 mm. In Hoffa's disease, the fatty tissue in the knee joint shows localised changes of the structure, scars are echo-poor, homogeneous structures within the solitary Hoffa lipoma. Postoperatively implanted metal can be observed and its position can be judged. The raised tibial cortical layer after Bandi's operation can be visualised in the sonogram.