Objective: Retrospective analysis of consecutive paediatric patients treated surgically for high-grade spondylolisthesis by one of three circumferential surgical procedures with emphasis on complications and patient outcome measurements.

Methods: Between 1980 and 1998 fourty patients underwent anterior-posterior correction for Meyerding Grade 3 or 4 isthmic dysplastic spondylolisthesis. Ten patients were treated with an anterior reduction according to Louis and anterior interbody fusion followed by posterior decompression and instrumented fusion (group A). Fourteen patients underwent posterior decompression followed by anterior reposition and fusion with tricortical iliac bone crest and posterior instrumented fusion (group B). Sixteen patients underwent progressive reduction by halopelvic traction followed by anterior and posterior fusion (group C). All patients completed the North American Spine Society (NASS) outcome questionnaire and the SF-36. The cosmetic assessment was performed by means of a VAS. The mean follow-up period for group A was 13,5 years, for group B 5,5 years and for group C 15,4 years, respectively.

Results: The three groups were comparable with respect to age at operation, radiographic measurement of the slip, lumbosacral kyphosis and lumbar lordosis. The incidence of postoperative extensor hallucis longus weakness was 33% in group A, 50% in group C and 0% in group B (p< 0.001). Pearson correlation coefficient revealed a positive correlation between extensor hallucis longus weakness and the degree of correction of the lumbosacral kyphosis (P=0.56, p=0.024). Postoperative reduction of the sagittal slip (A: 64%, B: 44%, C: 50%) and lumbosacral kyphosis (A: 27°, B: 16°, C: 27°) was significant in all three groups. The incidence of pseudarthrosis was 10% in group A, 7% in group B and 6% in group C. SF-36 and NASS outcome questionnaire results have not been found statistically significant among the groups.

Conclusion: Outcomes of function, satisfaction and cosmesis are satisfactory in all three surgical groups. Posterior decompression followed by anterior reduction and fusion using tricortical iliac crest bone graft and posterior instrumented fusion lack neurogenic complications. Therefore it is the standard surgical procedure for severe isthmic dysplastic spondylolisthesis at our department.