[How to obtain a a front-view of the knee in extension? Anatomy and tomodensitometry show the superiority of the radiographic method based upon the middle 3d of the knee compared with the one based upon posterior condyles].
1) To obtain a true "en-face"" projection of the middle third of a knee, we must, on the fluoroscopic screen, put the apex of the femoral intercondyloid fossa just above the middle of the tibial intercondyloid eminence. The extended knee rests on its middle third which thus constitutes the guide-mark for the gonometry. This "middle third" projection gives also the opportunity to measure adequately the physiological lateralisation of the patella, which normally does not exceed 12% of the maximal width of the femoral epiphysis, or practically 12 millimeters. 2) The method using the perpendicular to the posterior aspects of the femoral condyles is not always accurate because of the variable curvature of the intercondyloid fossa and the discrepancy between the depths of the femoral condyles. The medial condyle would be frequently a little longer in the woman than in the male. This method gives a true "en-face"" projection of only the posterior third of the knee and is thus not reliable to assess the position of the patella and to perform a valid gonometry.
D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
Comment obtenir un genou de face en extension? L'anatomie et l tomodensitométrie montrent la supériorité de la méthode radiographique basée sur le tiers moyen du genou par rapport à celle basée sur les condyles postérieurs.