[Patella dislocation with special reference to cartilage damage].

Dislocations of the patella are discussed in the light of their pathogenesis, their possible injury pattern and their consequences. An exemplary case is presented. Especially the injury to the retropatellar cartilage with following chondromalacia--sometimes initiating the development of patellofemoral osteoarthritis--renders the dislocation of the patella a severe injury of the knee region. In case of spontaneous reduction and uncertain history the diagnosis may be difficult. The dislocation of the patella can be suspected if a hemarthrosis is found without an instability of the knee ligaments. The possibilities of an operative repair are described with special regard to the cartilage injury. Importance was layed upon the shape variabilities of the patellofemoral joint predisposing to recurrent dislocation.