The use of primary internal fixation in spondylolisthesis.

A prospective randomized study was designed to examine differences in the primary fusion rate between two surgically treated groups of patients with spondylolisthesis. Twenty-seven patients underwent L5 laminectomy (Gill procedure) and L5 nerve root decompression. Fourteen patients (group I) underwent in-situ posterolateral fusion, thirteen patients (group II) received internal stabilization with the Steffee plate and screw system. All patients were followed for a minimum of two years. Ten of fourteen (72%) patients treated with non-instrumented fusion went on to union. Ten of thirteen (78%) patients treated with internal fixation achieved union. No statistically significant increase in the primary fusion rate occurred with addition of internal fixation compared to non-instrumented posterolateral grafting alone.