Growth-friendly Technique or Posterior Spinal Fusion With T-construct Pelvic Fixation in Nonambulatory Spinal Muscular Atrophy With Severe Scoliosis

Abstract

Background: The surgical treatment of scoliosis in type 2 spinal muscular atrophy (SMA2) is challenging and little described in the literature due to its rarity and fragility of the patients. The aim of this study was to review the surgical strategies and outcomes in patients with SMA2 who underwent surgery for scoliosis at a French reference neuromuscular center.

Methods: All consecutive patients with genetically confirmed SMA2 who underwent spinal surgery between 2009 and 2022 at our French reference center were retrospectively analyzed. They were divided into 2 groups, according to their primary surgery: either magnetically controlled growing rods (MCGR) or posterior spinal fusion (PSF). Demographic, respiratory, and radiologic parameters were collected preoperatively and at the latest follow-up. All complications were reported. Patients and/or caregiver-reported outcome questionnaires were also used to assess the improvement of sitting posture.

Results: Seventeen patients underwent MCGR, and 9 patients underwent PSF during the inclusion period. Mean follow-up was 5.3±1.8 years in the MGCR group, and 8.0±4.5 years in the PSF group. The average age at surgery was 9.7±1.6 years in the MCGR group and 12.6±1.7 years in the PSF group. Pelvic fixation was performed using a Tconstruct (2 sacral and 2 iliac screws). PSF was performed with all levelled pedicle screws. In the MGCR group, upper thoracic fixation was lateral ribs (n=4), vertebral on three levels (n=9), or hybrid costo-vertebral (n=4). No blood transfusion was required. No differences were found between preoperative and postoperative lung function tests for the 2 surgical procedures. The major curve correction rate was 44% in the MCGR group and 55% in the PSF group. The pelvic obliquity at last follow-up was <5 degrees in all patients. Three unplanned surgeries occurred: 1 MGCR change after lengthening and 2 PSF-one for proximal hook migration and one for infection. All patients improved their ability to sit.

Conclusion: In this series, PSF and MGCR allowed stable radiographic and respiratory results, with a reduced rate of global complications. Pelvic fixation with T-construct was a reliable and effective technique to correct pelvic obliquity in this population of patients.

Keywords: T-construct; magnetic growing rods; pelvic fixation; posterior spinal fusion; respiratory function; scoliosis; spinal muscular atrophy.