Use of a thirty-degree caudal tilt radiograph in the shoulder impingement syndrome.

The formation of a bony spur or prominence at the anterior acromion is an important pathologic factor in impingement syndrome, and the detection and estimation of the size of such a spur are also important for diagnosis and treatment. We investigated the usefulness of a 30° caudal tilt view of the shoulder for detection of the bony spur. A 30° caudal tilt view was used to detect a spur in 52 of 73 joints diagnosed as having the impingement syndrome, whereas the spur was detected in only 27 joints when routine anteroposterior films were used. Only sufficiently larger spurs that projected toward the coracoid process could be recognized on anteroposterior films. Because the 30° caudal tilt view demonstrated the exact architecture of the spur encountered at operation, it was useful not only for preoperative planning but also for evaluation of the adequacy of surgery.