[Plica medialis, patellar shape and chondromalacia].

The influence of the shape of the patella and of the plica medialis parapatellaris on cartilage changes was studied in 161 knee joints (autopsy material). The cartilage changes were cartographically recorded and transferred to a computer matrix. The type and size of the plica were documented. The material studied was classified according to age, patellar shape, and degree of prominence of the plica. Cartilage lesions were found on the odd facet even in younger material. The cartilage damage depended on the shape of the patella. The more convex the medial facet, the less cartilage damage had occurred. The odd facet was found to be the point of origin of chondromalacial changes on the medial side of the patella. It is assumed that the plica medialis parapatellaris and the fat fold located there encourage the development of chondromalacia, especially where the medial facet is convex in shape.