This paper is based on 143 cases of spondylolisthesis, in which operation was performed at the Mayo Clinic in the years 1922 to 1940 inclusive. In 79 per cent. of the cases the patients were twenty to forty-nine years of age. One hundred and twelve, or 78.3 per cent., of the patients were males, while thirty-one, or 21.7 per cent., were females. In 72 per cent. of the cases, the patients had been engaged in occupations which entailed heavy work. There was a history of trauma in ninety, or 62.9 per cent., of the cases. In 10.3 per cent. of the cases the history and appearance of the patient did not immediately cause the examining physician to consider the presence of spondylolisthesis. In these cases the diagnosis was made incidentally during extensive physical and roentgenographic examination to determine the cause of obscure symptoms. Backache, with or without pain in the legs, was the chief symptom in 90.2 per cent. of the 143 cases. In 95.1 per cent. of the cases, the subluxation involved the fourth and fifth lumbar vertebrae or the lumbosacral interspace. In cases in which sciatic pain is a prominent symptom, it is necessary to consider the coexistence of protrusion of an intervertebral disc.

Postoperative complications occurred in fourteen cases. Infection occurred in eight of these cases and phlebitis in six. Follow-up data were obtained in 118 of the 143 cases. In the 118 cases the results were as follows: good in seventy-one, or 60.1 per cent.; improved in thirty-three, or 28 per cent.; and unimproved in fourteen, or 11.9 per cent. In 87.6 per cent. of the 118 cases, the patients were able to engage in a gainful occupation after operation, and in 66.4 per cent. of the cases the patients were able to resume their former occupations.