A New Position for the Examination of the Lumbosacral Area

Abstract

Ordinarily, in the x-ray examination of the lumbosacral area, the patient assumes a recumbent position on the table. Stereo films in the anteroposterior position, flat films in the two three-quarters oblique positions, and a flat film in the lateral position are probably made. In none of these positions is there any resemblance to the position assumed by the patient while at work, either sitting or standing. This is particularly true in those cases of rather obscure or indefinite back pain. Such recumbent positions do not record the relationship which the bony structures assume with the patient upright and possibly lifting. With this observation in mind, several plans were attempted with the object of revealing the changes which the upright position might produce. All the attempts failed except one, that of having the patient stand, strapped to the table, supporting a 25-pound sand bag on each shoulder. This is the plan in use to-day. The technic is as follows: The patient is placed in the usual recumbent position on the x-ray table. His feet are against the foot rest. The compression band is secured across the middle of the thighs and tightened. The tube is placed as nearly as possible over the central part of the upper pelvis, determined by centering over the middle of a line drawn from one anterior superior iliac spine to the other. The central beam is directed to it at right-angles. The center of the movable grid is placed in the path of the central beam and the cassette is placed in the center of the grid pan. In this position the first film, a flat anteroposterior exposure, is made. Without allowing the patient to move, the table is now raised to the upright position, the tube is centered exactly as before, maintaining the same tube distance. The grid and the cassette are again centered. The sand bags are placed on the patient's shoulders and this is done none too gently. He is encouraged to relax, using only such muscles as are required to maintain the upright position. The second exposure is then made. This position requires a little longer exposure than the upright position does on account of an increase in the amount of soft tissue in and around the pelvis. In both positions, either anteroposterior or lateral exposures may be made, or both. In the use of this technic four things must be done diligently: the tube distance must be constant; the relative positions of the tube, patient's pelvis, and the cassette must be constant; the compression band must be below the pelvis, and the patient must carry the weight of the sand bags. After processing, the films are viewed side by side or superimposed. This method is not intended to replace the usual examinations of the lumbosacral region from which a diagnosis of organic pathology is desired. It is not intended as an aid in the diagnosis of bone and joint disease, but it is intended as a functional diagnostic method.