Purpose: Patients with spinal muscular atrophy (SMA) are often treated with growth friendly devices such as vertical expandable prosthetic titanium rib(VEPTR) and magnetically controlled growing rods(MCGR) to correct spinal deformity and improve pulmonary function. There is limited data on this topic, and the purpose of this study was to assess the effect of these constructs and the addition of chest wall support (CWS) on spinal deformity, thorax morphology and pulmonary outcomes.
Methods: This is a retrospective analysis of prospectively collected data. We included patients with chest wall deformity and scoliosis secondary to SMA who were treated with growth friendly interventions and had two-year follow-up. Descriptive statistics and univariate analyses were performed.
Results: This study included 66 patients (25% MCGR, 73% VEPTR, 2% unknown). Approximately 23% of constructs included CWS. The average Cobb angle improved from 67° (SD: 27°) to 50° (SD: 26°) at 2 years in patients with CWS (p = 0.02), and from 59° (SD: 20°) to 46° (SD: 15°) at 2 years in patients without CWS (p < 0.01). Hemithorax height improved in patients treated with and without CWS (p = 0.01), but hemithorax width only improved in patients with CWS (p = 0.01). One patient with CWS and two patients without CWS required additional respiratory support at 2 years. The rates of postoperative complications were not significantly different in patients treated with and without CWS (p = 0.31).
Conclusions: Growth friendly constructs improve spinal deformity and may be effective in altering the progression toward respiratory failure in patients with SMA. Patients treated with CWS have significant improvements in thorax morphology compared to patients without CWS.
Keywords: Early-onset scoliosis; Growing rod; Spinal muscular atrophy; Thoracic insufficiency syndrome; Vertical expandable prosthetic titanium rib.