Treatment of spondylolysis and spondylolisthesis with Cotrel-Dubousset instrumentation: a preliminary report.

We treated 50 consecutive patients with Cotrel-Dubousset instrumentation (CDI) for symptomatic spondylolisthesis. Average follow-up was 25 months. Fusion in situ was performed in 32 of 44 patients with mild spondylolisthesis, while 12 patients had reduction in conjunction with neural decompression. Two of six patients with severe spondylolisthesis who were treated via a single posterior approach had loss of reduction and nonunion. In another patient a Grade III spondylolisthesis could not be reduced via a posterior approach. Seventy-six percent of the patients had a good clinical result. The rate of solid fusion was 96%. One nerve root compromise recovered completely. One superficial wound infection healed uneventfully. This study suggests that combined anterior and posterior fusion is required for permanent and sufficient correction of severe spondylolisthesis even with CDI. Low-grade spondylolisthesis should be reduced only in conjunction with neural decompression.