The long-term effect of posterolateral fusion in adult isthmic spondylolisthesis: A randomized controlled study

111 patients with adult lumbar isthmic spondylolisthesis were randomized to undergo either a 1-year exercise program, a posterolateral fusion without pedicle screw instrumentation, or a posterolateral fusion with pedicle screw instrumentation. The results of the study suggested that posterolateral fusion with and without pedicle screw instrumentation achieved significantly better clinical outcomes when compared with a 1-year exercise program. However, some short-term improvement was lost at long term follow-ups.