Long-term results in lumbosacral interbody fusion for spondylolisthesis

Out of a group of 235 patients who underwent a lumbosacral interbody fusion, 24 who were operated on for spondylolisthesis and had a long follow-up period were isolated for careful clinical and radiological evaluation. All patients were examined 1 year after surgery and 10 years or more postoperatively. Bony fusion was achieved within 4 to 6 months in all cases except one. The clinical results, showed that all patients had a good or intermediate result after 1 year. After 10 years or more 20 patients still had a good result, three an intermediate result and one a poor result. Our special interest concerned the radiological behaviour of the discs above the fused segment. This was evaluated on flexion and extension films, preoperatively and 10 years postoperatively. After this period an instability, radiologically visible as a posterior shift of 3 mm or more, was found in three L4-5 segments. No instability was found in the L3-4 segments. The disc space height diminished in three cases in the L4-5 segment and in one case in the L3-4 segment. No definite conclusions could be drawn from the flexion and extension angles measured preoperatively and 10 years or more postoperatively. Analysis of the poor and intermediate results showed that low back pain may persist to some extent after previous posterior surgery. In two cases a correlation was found between narrowing and tilt of an L4-5 segment and pain. In these two cases there was also an inadequate correction of the preoperative olisthetic kyphosis. There was one case of persistent back pain without any clinical or radiological findings. Finally, of the 106 males out of the group of 235 patients, none had problems of postoperative sterility or persistent retrograde ejaculation.