A roentgenological and gross anatomical study of the variation in the interosseous distance between the radius and ulna during the rotation of the forearm was made on cadavers. It was found that the neutral position provides the widest interosseous distance at different levels of the forearm compared with all other supinatory and pronatory positions. The average of the interosseous distances is greatest at the junction of distal and middle thirds of the radius, except in pronation 90°.
Our observations show that the magnitude of the interosseous distance is largely proportional to the radius and ulna being in the same plane in a particular position of rotation of the forearm. In the neutral and supinatory positions, the point of the widest interosseous distance occurs more frequently in the middle third of the forearm, and in pronatory positions, in the distal third. Observations were also made on ligamentous specimens for the variation of tension of the interosseous membrane and of various planes occupied by the radius and ulna at different positions of rotation. The interosseous membrane was found to be taut in the neutral position in its major portion but lax in both pronation and supination.