The effect of bracing on pulmonary function in adolescent idiopathic scoliosis: a systematic review with meta-analysis

Abstract

BACKGROUND: The impact of bracing on pulmonary function in adolescent idiopathic scoliosis (AIS) remains unclear, with prior studies reporting variable findings. Some report short-term reductions during brace wear, whereas long-term impairment has not been consistently demonstrated. To clarify these effects, we conducted a systematic review and meta-analysis of controlled clinical trials. METHODS: PubMed, Web of Science, and Scopus were searched from inception to 15 October 2025, following PRISMA 2020 guidelines, along with screening of reference lists. Eligible studies were controlled trials evaluating the effects of bracing on pulmonary parameters in AIS. Two reviewers independently screened and extracted data, evaluated methodological quality using the Cochrane Risk of Bias tool, and performed pooled analyses. RESULTS: Fourteen studies met the inclusion criteria, involving 548 participants. Pooled findings indicated short-term reductions in several pulmonary measures. Immediate decreases were observed in total lung capacity (SMD = - 0.83, p = 0.01) and functional residual capacity. FVC and FEV(1) showed significant short-term reductions at 1 month (SMD = - 0.68 to - 0.76, p < 0.001), followed by normalization at 2 months, and again a moderate decline at 6 months (SMD = - 0.62, p = 0.007). The FEV(1)/FVC ratio was significantly reduced at 6 months (SMD = - 1.05, p = 0.007). Changes in peak expiratory flow and maximum voluntary ventilation were also reported across 1-8 months. Many assessments were conducted in‑brace, suggesting that the observed reductions may reflect transient mechanical restriction, rather than persistent physiological impairment. Out‑of‑brace or longer‑term measurements were generally non‑significant. CONCLUSIONS: Current evidence indicates that bracing in AIS may lead to short‑term or in‑brace reductions in lung volumes and ventilatory parameters, while persistent or irreversible impairment after brace removal has not been demonstrated. These findings support a mechanical rather than pathological explanation for most observed changes. Incorporating mitigating strategies, such as respiratory muscle training, may help manage short-term respiratory effects during brace treatment.