Fusionless spinal surgery in children with spinal muscular atrophy type 1 with bipolar system: a preliminary communication

Spinal muscular atrophy (SMA) is a severe childhood neuromuscular disorder caused by degeneration of lower motor neurons, leading to muscle atrophy. SMA type 1 (SMA1) is the most severe form and the leading genetic cause of infant mortality. While recent therapies such as nusinersen and onasemnogene abeparvovec have improved survival and ventilation-free time, affected children develop pelvic asymmetry and progressive spinal deformity, impairing the sitting position. Minimally invasive fusionless surgery (MIFS) using the Bipolar system has shown promising outcomes in SMA types 2 and 3, but evidence in SMA1 remains limited. This retrospective study reviewed medical records of SMA1 patients treated with MIFS using the Bipolar system between July 2023 and January 2025. Pre- and post-operative parameters were compared using paired Student's t-tests. Sixteen SMA1 patients (mean age: 8.1 ± 2.2 years; mean weight: 18.0 ± 3.2 kg) underwent MIFS with no surgical or anesthesiologic complications. Cobb angle improved from 71.8 ± 8.7 to 43.2 ± 9.2 ° (P < 0.001), pelvic obliquity from 12.7 ± 9.2 to 7.8 ± 6.1 ° (P = 0.0035), kyphosis from 62.9 ± 16.5 to 44.9 ± 14.1 ° (P < 0.001), and lordosis from 58.1 ± 15.3 to 43.5 ± 11.5 ° (P < 0.001). T1-S1 spinal length increased from 27.1 ± 1.8 to 30.9 ± 2.0 cm (P < 0.001), and thoracic width from 167.4 ± 12.0 to 181.5 ± 15.8 mm (P = 0.0017). The bipolar system appears to be a safe and effective surgical option for managing scoliosis in SMA type 1 patients, achieving significant correction of spinal and pelvic parameters without complications.