During the past two years it has been the routine procedure of my associates and myself to take anteroposterior and lateral x-ray pictures of the dorsal, lumbar and sacral spine, as well as an anteroposterior view of the pelvis, of all patients complaining of a painful back. The procedure was instituted because many conditions of the spine gave neither subjective symptoms nor objective findings at the level of the lesion. As a result of the complete roentgen study, a lesion consisting of a narrowing or a complete loss of the intervertebral disk between the fifth lumbar and the first sacral vertebra was noted in the majority of patients suffering with symptoms of sciatic irritation. Ayers1reported thirty-six cases of low back pain, in twenty-seven of which the patients had pain down one or both extremities, and all showed a thinning of the lumbosacral cartilage or an arthritic involvement of