Purpose: To evaluate changes in pulmonary function tests (PFT) at 5 years post-operatively in patients with adolescent idiopathic scoliosis (AIS) and to determine whether these changes are progressive or static after 2 years.
Methods: AIS surgical patients with pre-operative and 5 year post-operative forced expiratory volume (FEV) and forced vital capacity (FVC) were included. The percentage of patients with pulmonary impairment at 5 years was calculated. Repeated measures ANOVA was used to evaluate changes between pre-operative PFT and 5 years post-operative PFT and to determine whether the changes differed between curve types and approach. A sub-analysis of patients with 2 year data was performed to determine whether PFT changes were static or progressive.
Results: Two hundred and sixty-two patients had undergone pre-operative and 5 year post-operative PFTs. At 5 years, 42% were normal, 41% had mild impairment, and 17% had moderate-severe impairment. Overall, there was a decline in % predicted FVC (p < 0.05); FEV remained stable. There was no difference based on major curve type (p > 0.05). Anterior instrumentation cases declined significantly between pre-operative PFT and 5 years post-operative PFT (FEV: - 10% open, - 6% thoracoscopic; FVC: - 13% open, - 8% thoracoscopic) (p ≤ 0.02). The posterior cases remained stable (2% FEV, p = 0.7; - 0.6% FVC, p = 0.06). A subgroup of 90 patients with 2 year post-operative PFTs demonstrated that changes were progressive between 2 and 5 years post-operatively. The average change in FVC from 2 to 5 years was significantly different between the anterior open (- 9%) and posterior-only (0.7%) groups (p = 0.015).
Conclusion: In patients who underwent anterior instrumentation, PFTs declined from the pre-operative to the 5 years post-operative time point. There was a progressive decline of 4-10% beyond 2 years post-operatively. Patients who underwent posterior instrumentation remained stable. These slides can be retrieved under Electronic Supplementary Material.
Keywords: Adolescent idiopathic scoliosis; Anterior spinal fusion; Posterior spinal fusion; Pulmonary function.