Effects of bracing on pulmonary function in adolescent idiopathic scoliosis: a systematic review

BACKGROUND CONTENT: Adolescent idiopathic scoliosis (AIS) is the most common form of 3-dimensional pediatric spinal deformity, characterized by abnormal lateral displacement and rotation. Full-time rigid bracing is often prescribed to prevent curve progression during skeletal growth. Directed force is applied to the apex via the rib cage to achieve satisfactory in-brace correction. The short- and long-term effects of bracing on the pulmonary function remain unclear.

To study the effects of bracing on the pulmonary function of AIS patients.

Systematic review.

FEV1, FVC, VC and FEV1/FVC ratio.

Following the PRISMA guidelines, PubMed, Cochrane Library, Scopus, EBSCOhost and PEDro were analyzed from inception to 15 October 2025, searching keywords of "AIS", "bracing" and "Pulmonary function". Original English research reporting outcomes on AIS patients with bracing as a core intervention and measurements of pulmonary function parameters are included, while research including other interventions are excluded. 15 studies were selected, totaling 578 patients and 731 controls. ROBINS-I (Risk Of Bias In Non-randomized Studies -of Interventions) was used to assess risk of bias. Data extraction is performed on the papers, while the quality appraisal was done using the MINORS methodology score. Due to the heterogeneity of bracing regimen and pulmonary function outcomes adopted across included studies, a structured narrative synthesis approach instead of the meta-analysis was taken to summarize the findings.

Short-term: Bracing is associated with a reduction in pulmonary function; however, there is no change in FEV1/FVC ratio. Long-term effects: AIS patients show a decrease in pulmonary function when the brace on in both the first and eighth month of bracing compared to brace off. Adolescents who received bracing treatment showed an improvement in pulmonary function 25 years after treatment compared to those untreated; however, their respiratory function remains worse than that of those without scoliosis.

The principle and mechanism of bracing pose a restrictive pattern on patients with AIS. There is an immediate decrease in the pulmonary function when the patients are braced. The decline in pulmonary function both in and out-brace increases when the patient is braced over a prolonged period of time (1 month vs 8 months). However, in longitudinal follow-up of up to 25 years post-treatment revealed that the pulmonary functions (both FEV1 and VC) improved significantly compared to pre-bracing (p < 0.001, with medium standard mean difference of 0.4 and 0.614 respectively), suggesting possible long-term benefits of bracing.