Treatment of severe spondylolisthesis in adolescence with reduction or fusion in situ: long-term clinical, radiologic, and functional outcome.

Study Design: Retrospective follow-up study with two cohorts: one treated with reduction and the other with fusion in situ.
Objective: To assess the long-term effects of reduction versus fusion in situ on lumbar spine in children and adolescents with severe L5 isthmic spondylolisthesis.
Summary of Background Data: Severe isthmic spondylolisthesis is commonly treated with fusion in situ, but modern surgical techniques and instrumentation permit the reduction of a severely slipped fifth lumbar vertebra. Advocates of one or another of these procedures present different claims to defend their choice. However, to our knowledge, no long-term results of the reduction maneuver exist.
Methods: Between 1983 and 1991, 22 adolescents with severe (more than 60%) slip were treated surgically. In 11 of them, reduction was performed with a Magerl/Dick transpedicular device, followed by fusion posteriorly from L4 or L5 to S1 and anteriorly from L5 to S1. In the others, fusion was performed in situ posteriorly from L4 (n = 7) or L5 (n = 4) to S1 and anteriorly from L5 to S1. The average age of patients at surgery was 14.7 years (range 10.7-18.5). Radiographs obtained before surgery, after surgery, and at the final follow-up evaluation were assessed for quality of fusion. In addition, magnetic resonance imaging was obtained at the last follow-up visit. Average follow-up time was 14.8 years (range 11.6-18.7). Physical examination, spinal mobility, and nondynamometric trunk strength measurements were used to assess, and Oswestry Disability Index and Scoliosis Research Society scores were used to calculate outcome at the last follow-up visit.
Results: In the reduction group, mean Oswestry Disability Index was 7.2 (range 0-20) and in the fusion in situ group, was 1.6 (range 0-4) (P = 0.0096). The Scoliosis Research Society total score averaged 90.0 (range 39-107) in the reduction group and 103.9 (range 93-120) in the fusion in situ group (P = 0.046). At the last follow-up evaluation, mean vertebral slip had decreased from the preoperative value of 90% to 57% in the reduction group but remained the same (80% vs. 78%) in the fusion in situ group (P = 0.04 and 0.013, respectively, for preoperative and postoperative comparison). On magnetic resonance imaging, disc degeneration above the fusion was more common in the reduction group (P = 0.004). None of the patients had spinal stenosis above the fusion. Nerve root canal impingement at the L5-S1 level was more common in the fusion in situ group (P = 0.03), but all patients were free of L5 nerve root symptoms. There was no difference in spinal mobility or trunk strength measurements between the groups.
Conclusions: The fusion in situ group seems to perform better in almost all clinical parameters measured. These findings suggest that fusion in situ should be considered as a method of choice in severe L5 isthmic spondylolisthesis.