Pulmonary function and exercise capacity in mild early-onset idiopathic scoliosis: a case‒control study

Early-onset idiopathic scoliosis (EOIS) is a spinal deformity that develops before the age of 10 years with unknown etiology. Scoliosis can lead to respiratory muscle weakness and decreased motor function. Nevertheless, the effects of mild EOIS on pulmonary function and functional exercise capacity remain poorly understood. Early detection is crucial to mitigate its impact on children's health and prevent progression. The aim of this study was to investigate the characteristics of pulmonary function and exercise capacity in children with EOIS and to identify influencing factors.

52 children with mild EOIS and 52 healthy controls matched for age and sex were recruited.Participants underwent pulmonary function test, a 6-minute walk test (6MWT) and Borg score assessments to evaluate subjective fatigue before and after 6MWT. Differences in forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow (PEF) and six-minute walking distance (6MWD) were compared between the two groups. Imaging parameters were measured from full spinal X-ray orthopantomograms taken in the standing position for the case group. Independent samples t-tests were used to analyze differences between the two groups, followed by multiple linear regression analyses to identify the influencing factors.

The case group exhibited significantly lower FEV1/FVC and 6MWD but a higher Borg score compared to the control group (P = 0.009, P = 0.015, P < 0.001). Within the case group, the FEV1/FVC was significantly decreased in the right thoracic scoliosis subgroup compared with the left thoracic scoliosis subgroup (P = 0.006). Height, Cobb's angle and PEF were significant factors affecting the 6MWD of EOIS (P = 0.003, P = 0.005, P = 0.002), FVC was related to the height, side bend position and side bend direction (P < 0.001, P = 0.030, P = 0.013), and FEV1 was affected by age, weight and type of side bend (P = 0.016, P = 0.019, P = 0.016).

Mild pulmonary and exercise capacity restrictions appear early in mild EOIS. Exercise capacity is influenced by lung function and exhibits a negative correlation with the severity of scoliosis. Pulmonary function in right thoracic scoliosis was significantly lower than that in left thoracic scoliosis. Early identification of these functional declines is crucial for implementing timely interventions to prevent further deterioration.