Special trauma oblique radiographs of the knee were designed for the
purpose of demonstrating the patella radiographically in a manner that
would free it from the shadow of the distal end of the femur. These
radiographs are made by directing the x-ray tube at an angle of 45 degrees
and making two exposures, with the film placed first on the lateral and
then on the medial side of the injured knee. These two radiographs have
been found to be useful for delineating the extent of fractures of the
patella as well as abnormalities of the tibial plateau.