Progression of Lumbosacral Spondylolisthesis

Abstract

SUMMARY A series of fifty‐one cases of lumbo‐sacral spondylolisthesis under the age of thirty years were followed up for a minimum period of one year. The overall progression rate in this series was 24%, but more significantly, the incidence of progression in adolescence was 38%. Furthermore, there was a marked difference in the incidence of progression in the dysplastic type (32%) compared with the isthmic type (4%). Radiological studies showed that adolescent progression occurred concurrently with significant structural changes in both the 5th lumbar vertebra and the sacrum. It was felt that the loss of support of the posterior vertebral complex in dysplastic spondylolisthesis resulted in an interference in the vertebral growth once displacement exceeded 25%, demonstrating that progression may occur before a fusion becomes sound. Late progression was not accompanied by structural changes, and was due to a loss of posterior ligamentous and disc integrity.