Evaluation of Efficacy and Safety of All Pedicle Screw Posterior-Only Surgery in Patients with Dystrophic Neurofibromatosis Scoliosis

Abstract

Background Data: Neurofibromatosis type 1 (NF-1) patients with dystrophic changes of the spine develop severe spinal deformity and/or instability and always need early surgical treatment. Combined anterior-posterior fusion was the treatment of choice of such curves because of the risk of progression and pseudoarthrosis even in the presence of solid posterior fusion mass. Recent 3rd-generation posterior stabilization systems using pedicle screw fixation allow better 3-column purchase and 3D control and correction of deformity and stable posterior fixation of the spine preventing progression of the curves. Posterior-only surgery has been recently used in dystrophic NF-1 scoliosis due to use of pedicle screws fixation and development of different types of posterior release/osteotomies which lead to successful and sustained correction of these curves. Study Design: A retrospective clinical cohort study. Purpose: To study the results of posterior stabilization alone using all pedicle screws fixation in NF-1 patients with dystrophic scoliosis. Patients and Methods: 16 patients with NF-1 having dystrophic scoliosis were treated by posterior instrumentation using all pedicle screws. There were 5 female and 11 male patients and the average age was 13 years (range, 9-16 years). The study was done in the period between 2009 and 2016. Preoperative clinical examination included examination for neurofibromatosis, assessment of curve flexibility, and thorough neurological examination. Radiological examination included standard plain X-rays, anteriorposterior (A-P) and lateral and flexibility views, and MRI. Screw density of the whole construct and of the apical region (two vertebrae above and below the apex) was calculated. Functional outcomes were assessed by the ODI and SRS-30 scores at the last follow-up. Results: The mean follow-up was 5.15±1.78 years (range, 3-8). The mean Cobb angle improved in the coronal plane from 67.13±11.88 (range, 45-90 •) to 20±8.9 (range, 6-30 •) showing 70.1±11.2%. The mean preoperative sagittal plane deformity significantly improved from 61.82±20.28 (range, 35-90 •) to 25.91±7.68 (range, 10-35 •) postoperatively yielding 53.15±21.43 (range, 25-83.33%) mean correction with insignificant loss of correction at last follow-up. Loss of correction was 2±1.8% and 1.8±2.1% in the coronal and sagittal planes, respectively. At last follow-up the average SRS-30 score was 121±17.