Effects of bracing on lung function in idiopathic juvenile kyphosis

Although considerable information is available on the effects of bracing on lung function in kyphoscoliosis, there is a paucity of data on idiopathic juvenile kyphosis (IJK). The present study was designed to investigate the immediate effect of bracing on lung function in children and adolescents with mild-to-moderate IJK. Spirometry, measurement of lung volumes, and arterial oxyhemoglobin saturation (SaO(2)) were performed in 24 patients, 9-17 years of age, who were treated with a corrective brace for mild-to-moderate IJK (Cobb angle, 46-75 degrees ). Children were studied when braced and unbraced. When children were unbraced, mean percent predicted values (+/-standard deviation) for total lung capacity (TLC), vital capacity (VC), functional residual capacity (FRC), and forced expiratory volume in 1 sec (FEV(1)) were 100.0% (+/-13.0%), 92.7% (+/-14.2%), 108.2% (+/-20.4%), and 95.0% (+/-16.3%), respectively. With the brace on, significant reductions occurred in all lung function measurements: TLC decreased by 9.5% (P < 0.001), VC by 9.3% (P = 0.001), FRC by 14.2% (P = 0.005), and FEV(1) by 8.9% (P = 0.009). SaO(2) decreased from 96.2% (+/-1.6%) to 95.2% (+/-1.4%) (P = 0.027). An inverse relationship was observed between pre- and postbracing change in TLC and Cobb angle children (P = 0.021). Our findings indicate that corrective bracing in mild-to-moderate IJK results in mild lung restriction and a clinically insignificant drop in SaO(2). The effect of bracing on TLC decreases as the severity of kyphosis increases in these patients.