[Determination of femoropatellar joint dysplasia (author's transl)]

On the basis of more than 1400 tangential X-rays made with Knutsson's technique, the author qims to demonstrate, employing optical and measurement criteria, the limits between normal conditions and dysplasias. Since there are no fixed boundaries, these two areas can only be delimited from each other with sufficient accuracy by means of an inter-mediate zone. The patella is differentiated according to its shape in euplasia, medial hypoplasia and dysplasia, corresponding to the trochlea in Types I-V. In relation to the knee joint in question, there is a high degree of correlation between the development of the patella and the trochlea. All in all, a dysplasia can be determined more easily and more accurately at the trochlea than at the patella, since the patella is subject to greater projectural changes and the points of measurement are more difficult to establish. Ficat and Bizou's condylar depth index and the condylar-joint surface angle of Brattström are recommended as especially suitable methods of measurement. Since the shape of the trochlea changes as a function of the extent to which the knee is bent, the latter must be cited in comparative investigations.