Minimally Invasive Fusionless Surgery for Scoliosis in Spinal Muscular Atrophy: Long-term Follow-up Results in a Series of 59 Patients

Abstract

Background: Treatment of spinal muscular atrophy (SMA) scoliosis has evolved in the last decade, with the emergence of fusionless surgical techniques that allow correction of the deformity before the end of growth spurt. These techniques are expected to delay definitive spine fusion and preserve trunk growth. Purpose: The aim was to evaluate long-term clinical, radiologic, and respiratory outcomes of a minimally invasive fusionless surgery (MIFLS) in SMA scoliosis. Methods: All children affected with SMA scoliosis who underwent MIFLS in our department from 2011 to 2019 were included. The instrumentation consisted in a bilateral sliding rod construct from T1 to the sacrum, anchored proximally by double-hook claws and distally by iliosacral screws. Clinical, genetic, respiratory and radiographic data were retrospectively reviewed. A patient's satisfaction survey was performed. Results: A total of 59 children with genetic confirmation of SMA (9SMA1c, 47SMA2, and 3SMA3) underwent MIFLS at a mean age of 11 ± 1.9 years. All of them were nonwalker at the time of surgery. Twenty-six were treated with intrathecal Nusinersen. Mean follow-up was 5.2 years (2 to 9.6 y). Mean major coronal curve improved from 79 ± 15 to 41 ± 16 degrees and pelvic obliquity decreased from 24 ± 11 to 5.9 ± 4 degrees. Mean space available for lung improved from 77% to 93%. Mechanical or infectious complications occurred in 9 patients, with removal of the implant in 1. 6 children required unplanned surgeries. Postoperative bracing was needed in 13 children. Mean gain weight 3 years after the first surgery was 6 kg. 91.5% of patients had a positive satisfaction of the surgery. There was no significant impact in respiratory function postoperatively. Only 30 children required rod lengthening procedures, with a mean interval between procedures of 1.9 years (0.5 to 3.7 y). No arthrodesis was required at last follow-up in any patient. Conclusion: Bipolar MIFLS in SMA preserves spinal and thoracic growth without interference with respiratory function. It provides a significant correction of spinal deformity and pelvic obliquity, having a reduced rate of complications. The correction of spinal deformity was maintained at long term, not requiring definitive fusion at the end of growth. Level of Evidence: Level IV.

Bipolar Fusionless Versus Standard Fusion Surgery in Neuromuscular Scoliosis

“…The BFC allowing further growth of the spine is therefore indicated in immature patients, as confirmed by our own study, allowing early removal of bracing, which has been demonstrated to have a negative impact on the quality of life and treatment satisfaction while not avoiding curve progression 36,37 . Furthermore, the solidity of the BFC makes final spinal fusion unnecessary, preventing further surgical interventions in skeletally mature patients, as demonstrated by long-term studies and recent meta-analyses 17,33,35 …”

“…36,37 Furthermore, the solidity of the BFC makes final spinal fusion unnecessary, preventing further surgical interventions in skeletally mature patients, as demonstrated by long-term studies and recent meta-analyses. 17,33,35 From our experience, some points are worth highlighting. In the first stages of our experience with BFC, we kept both SPF and BFC for NMC based on age (younger for BFC) and general conditions (better conditions for SPF).…”

“…Recently published studies by Gaume et al 17,[32][33][34] with up to 10 years of follow-up have demonstrated promising results for the treatment of NMS using BFC techniques: mean curve correction rate of 52%, 5% of mechanical complications, and 22% of surgical site infections. Our results are similar for coronal correction but better for surgical site infections, which could be related to factors unrelated to the surgical technique or to a lesser number of iterative distractions from our study.…”

The Minimally Invasive Bipolar Fixation for Pediatric Spinal Deformities: A Narrative Review

“…This technique was used in another series of 59 cases of scoliosis in spinal muscular atrophy (SMA) with the mean age at surgery of 11 years [28]. The mean preoperative body weight was 30.6 kg and 35.5 kg at the last follow up, with a mean gain of 6.1 kg at 3 years postoperatively.…”

Clinical Issues in Indication, Correction, and Outcomes of the Surgery for Neuromuscular Scoliosis: Narrative Review in Pedicle Screw Era

“…During the follow-up period (3 +9 years; range, 2 years to 6 +3 years), 12 mechanical complications and 16 wound infections were noted. Successful application of fusionless surgery in patients with spinal muscular atrophy was also reported [ 16 ]. The use of a growing rod may be an alternative technique for the treatment of neuromuscular scoliosis; however, a long-term follow-up study is essential to assess the outcome of the fusionless technique.…”