Scoliosis correction in spinal muscular atrophy : the influence of genetic severity, functional level, and disease-modifying agents on postoperative outcomes.

Abstract

Newer disease-modifying agents (DMA) targeting the involved survival motor neurone genes (<i>SMN1</i> and <i>SMN2</i>) associated with spinal muscular atrophy (SMA) have improved gross motor function, but their impact on postoperative outcomes after scoliosis correction remains unclear. This study aimed to evaluate postoperative outcomes following scoliosis surgery, specifically analyzing the impact of functional level, genetic severity, and DMA use. This retrospective cohort study evaluated patients with SMA (all types) who underwent scoliosis correction (growing rods (GR) or posterior spinal fusion (PSF)), with a minimum two-year postoperative follow-up. The primary outcome was 90-day postoperative complications by Clavien-Dindo (CD) grading. Secondary outcomes included age at surgery, SMA type, <i>SMN2</i> copy number, Hammersmith Functional Motor Scale-Expanded, forced vital capacity, DMA treatment (> one year duration, nusinersen/risdiplam/onosemnogene abeparvovec), intensive care unit (ICU)/hospital length of stay (LOS), days intubated, and curve correction. In total, 87 patients (60% female), SMA types 1 (29, 33%), 2 (47, 54%), and 3 (11, 13%), were included; follow-up duration was 6.8 years (SD 4.5). PSF was performed for 62 (71%) and GR for 23 (26%) at ages 12.0 (SD 2.4) and 6.2 (SD 2.9) years, respectively. For those with DMA treatment preoperatively, postoperative complications were less severe compared with no DMA use (CD 1 to 2/CD 3 to 5: 24 (100%)/0 (0%) vs 39 (65%)/21 (35%), respectively, p = 0.005) and ICU LOS (3.0 (SD 1.2) vs 4.7 (SD 4.7) days; p = 0.048), total hospital LOS (5.0 (SD 3.4) vs 7.8 (SD 4.8) days; p < 0.001), and days intubated (0.1 (SD 0.3) vs 1.8 (SD 2.3) days; p < 0.001) were less. DMA use was associated with no deterioration in pulmonary function (p = 0.094) compared with untreated patients (p < 0.001). Postoperative complications were less severe (CD 1 to 2) with preoperative DMA treatment. Coupled with DMA use, pulmonary function was stabilized after scoliosis surgery at almost seven years' follow-up. Improvements in hospital LOS and days intubated postoperatively are potential benefits of preoperative DMA treatment, serving to increase confidence to offering these major orthopaedic surgeries for patients with SMA. Improvements in outcomes may also reflect advances in surgical techniques and perioperative care over the study period. Further comparative studies are warranted to better isolate the specific impacts of DMA treatment.