Spinal instrumentation in the treatment of severe progressive spondylolisthesis.

By using A-frame instrumentation and direct distraction force, an exceptional correction can be obtained in patients with severe spondylolisthesis. Adolescent progressive spondylolisthesis should be considered as an entity separate from the lumbosacral anomalies such as spondylolysis and grades 0 and 1 spondylolisthesis without progression. An aplastic relationship appears to exist between the sacrum and the posterior superior wing of the ilium in the adolescent with progressive spondylolisthesis. Complications have been minimal but long-term observations of patients are necessary to evaluate the contribution of instrumentation in the treatment for severe progressive spondylolisthesis.