PURPOSE OF THE STUDY An optimal technique to surgically treat high-grade high-dysplastic (HG HD)spondylolistheses remains disputable. There are multiple surgical procedures described, ranging from a simple posterior fusion in situ without fixation through a standalone anterior lumbar interbody fusion with the oblique insertion of a structural bonegraft to instrumented full reduction and 360-degree fusion. At our department, preference is given to the instrumented monosegmental reduction and fixation by a fixator with Schanz screws. The aim of this paper is a prospective clinical and radiological evaluation of the group of operated patients below 30 years of age with HG HD spondylolisthesis with a slip greater than 50%. MATERIAL AND METHODS In the period from 11/2007 to 2/2017, a total of 29 patients with HG HD spondylolisthesis always of the L5-S1 segment were treated at the Department of Spinal Surgery of the First Faculty of Medicine of the Charles University and the Teaching Hospital Motol. They were 10 men and 19 women aged 10 to 28 years, with the mean age of 18.4 years. In 27 patients reduction and single-segment fixation of L5-S1 were performed as primary treatment, in one case decompression and noninstrumented-fusion only was carried out and in one case in situ fixation of L4-L5-S1 for distinctive osteoporosis. RESULTS The average duration of posterior surgery without the reconstruction of the anterior column was 88.9 min, in case of anterior fusion it was 46.6 min and in case of only posterior approach and fusion with the reconstruction of the anterior column it was 141.5 min. The average blood loss in the posterior fusion without the reconstruction of the anterior column reached 384.3 ml, in the stand-alone anterior fusion it was 21.6 ml. and in the posterior fusion with the reconstruction of the anterior column 430.0 ml. In 27 patients in whom the reduction was carried out, a shift of the L5 vertebral body observed on the CT scan prior to the surgery was 64.3% on average, while postoperatively and also at 6 months after the surgery during the follow-up examination it was 8.1%. A clear bone posterolateral fusion was found by the CT examination after 4-6 months in all 29 patients (100%, N = 29), while bone intersomatic fusion was reported in 25 cases (96.2%, N = 26). Altogether 6.9% of residual neurological deficits were observed. The statistical processing of VAS values for lumbar back pain and ODI values before the surgery and after two years confirmed a significant improvement of the clinical condition (p < 0.001). When asked whether they would undergo the same surgery with their current experience with the treatment, all the 29 patients answered "yes" and stressed the functional as well as the aesthetic results of the surgery. DISCUSSION In agreement with the other authors, the PT, SS and PI values are measured and we consider the SA, SDSG LSA and Dubousset s LSA assessments to be essential. All the measured values showed statistically significant changes postoperatively, only the pelvic incidence(PI) value remained unchanged. In patients with HG HD spondylolisthesis, we prefer reduction and the 360-degree monosegmental fusion, in the case of sacral osteotomy always using the posterior approach, in the cases where osteotomy is not performed using the next anterior approach. Even in the cases of the most severe deformities, we prefer to maintain the body of L5 and, where necessary, rather shorten the sacrum, which in our opinion leads to a better aesthetic result. CONCLUSIONS The reduction by single-segment instrumentation is a suitable alternative to the surgical therapy of HG HD spondylolistheses in young patients. It provides a high success rate of bone fusion and good clinical results including the aesthetic aspects. The complications associated with full reduction are not markedly higher than in other surgical techniques. Key words:spondylolisthesis, HGHD, high-grade, high-dysplastic, reduction, pelvic incidence, pelvic tilt, sacral slope.

Klinika spondylochirurgie 1 lékařské fakulty Univerzity Karlovy a Fakultní nemocnice v Motole Praha

Surgical treatment of high-grade high-dysplastic spondylolistheses in young patients - prospective monocentric study of 29 patients

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