Operative management of high-grade dysplastic L5 spondylolisthesis with the use of external transpedicular fixation: advantages and drawbacks.

PURPOSE: The aim of our study was to analyze clinical and radiographic outcomes of operative management of L5 high-grade dysplastic spondylolisthesis with the apparatus for external transpedicular fixation (AETF), and to compare the results of its use for reduction and spondylodesis.

METHODS

There were 13 patients with L5 dysplastic spondylolisthesis of grade 4 (Meyerding grading) and having a mean age of 25.0 ± 3.6 years. The management included two stages: gradual reduction with the AETF, followed by either isolated anterior spondylodesis with the same AETF (group 1, n = 8), or by spondylodesis using a combined method (internal transpedicular instrumentation and posterior lumbar interbody fusion [PLIF]) (group 2, n = 5). Clinical evaluation included pain (VAS scale) and functional status (Oswestry questionnaire [ODI]). Reduction and fusion completeness were assessed radiographically after treatment and at a mean follow-up of 2.1 ± 0.4 years.

RESULTS

Initial slippage was reduced by 51.6 % with AETF and was of grade 1 or 2. Reduction made up 31.1 % at follow-ups (grade 2 or 3). Pain decreased by 57.6 % (p < 0.01). The functional status improved. ODI decreased by 37.7 % (p < 0.01) after treatment and by 41.7 % (p < 0.01) at follow-ups. Fusion at the level of the involved segment was poor in group 1. All the cases fused in group 2.

CONCLUSIONS

The use of AETF for L5 high-grade dysplastic spondylolisthesis provides gradual controlled reduction of the slipped vertebra, decompression of cauda equine roots, and recovery of the local sagittal spinal column balance. It creates conditions for achieving stability of lumbosacral segments with combined spondylodesis (internal transpedicular instrumentation and PLIF). AETF is not suitable for spondylodesis due to a high rate of pseudarthrosis.