[Sport injuries of the extensor mechanism of the knee].

Injuries of the extensor mechanism of the knee occur frequently during sport activity. For a successful treatment they must be diagnosed early. Besides osseous structures the patellar tendon, the patella, the quadriceps muscle and tendon, retinacula and bursae can be affected. After initial clinical examination there are different noninvasive imaging modalities available for assessment of bone, cartilage, ligaments, tendons and soft tissue. Conventional radiographs are still the basic imaging tool for the clinician. Additional information about the osseous status is provided by computed tomography, whereas sonography plays an important role concerning diagnosis of soft tissue injuries. For the detection of cartilagenous, ligamentous or tendon lesions MRI is the superior non-invasive imaging modality.