Surgical management of severe spondylolisthesis in children and adolescents. Anterior fusion in situ versus anterior spondylodesis with posterior transpedicular instrumentation and reduction.

STUDY
DESIGN: A clinical and radiologic retrospective follow-up examination of patients treated surgically for severe juvenile spondylolisthesis.
OBJECTIVE: To compare two different surgical techniques in the management of severe (degree of slip > 30%) juvenile spondylolisthesis (anterior spondylodesis in situ versus combined anterior spondylodesis and posterior transpedicular instrumentation including reduction of the slipping vertebra) to determine if the advantages of the repositioning of the slipping vertebra and a decreased number of pseudarthroses because of the transpedicular instrumentation lead to clinical improvement despite showing better alignment radiologically.
METHODS: This study included 59 children and adolescents with severe spondylolisthesis of L5 who were treated surgically at the authors' orthopedic department between 1980 and 1992. Twenty-nine children received anterior spondylodesis (AS group), and 30 children received, in addition, a posterior reduction and transpedicular instrumentation (posteroanterior spondylodesis, PAS group).
RESULTS: Distribution of age, gender, preoperative clinical symptoms, and preoperative radiologic classification of the spondylolisthesis were comparable in both groups (average degree of slip for the AS group, 66%; that for the PAS group, 75%; angle of slip, 28 degrees and 36 degrees, respectively; sacral inclination, 31 degrees and 25 degrees, respectively). The postoperative follow-up period of the AS group lasted 125 +/- 22 months, considerably longer than that of the PAS group at 67 +/- 20 months. At the time of the follow-up assessment, the PAS group showed a reduced rate of pseudarthrosis (7% versus 24%), a reduced degree of slip (36% versus 59%), and a reduced lumbosacral kyphosis (14 degrees versus 26 degrees) in comparison with the AS group. The transpedicular instrumentation decreased the fusion time of osseous consolidation of the spondylodesis markedly (7 months versus 17 months, on average). Adverse effects and rate of complications were equal in both groups. The results failed to show any differences in favor of either of the two surgical techniques used either subjectively to the patient or objectively by means of clinical examination.
CONCLUSION: Anterior spondylodesis including posterior instrumentation and reduction was superior to the simple anterior fusion in situ for normalization of the lumbosacral profile and osseous consolidation of the spondylodesis. This result was not reflected in the clinical evaluation.