[Curvature and contact surface relations of the humeroradial joint].

The radii of curvature are measured in x-rays of 3 mm thick sagittal sections taken from the humeroradial joint of 7 newborns and 39 adults. The curvature of the humeral capitulum never corresponds to a definitive segment of a circular arch. The radii of curvature of the fovea capitis radii generally are greater than these of the humeral capitulum. From the given curvatures a distal shift of the radius can be deduced in case of elbow flexion or extension. Each 3 elbow-joints (supinated, pronated, max. pronated) are fixed in a max. extended, flexed and max. flexed position. The joint cavity then is filled with Pleximon. After polymerisation of the plastic the joints are opened. From the distribution of the plastic within the joint conclusion can be drawn that the surfaces will articulate only in part. The articulating surfaces often show small arthritic lesions of the cartilage.