Lin Y, Shen J, Chen L, Yuan W, Cong H, Luo J, Kwan KYH

J Bone Joint Surg Am. 2019 Jun 19;101(12):1109-1118.

BACKGROUND: Patients with congenital scoliosis often have restrictive pulmonary
dysfunction on static pulmonary function testing (PFT). Although frequently
asymptomatic during daily activities, these patients are generally assumed to
have reduced exercise capacity. The aim of this study was to use dynamic
cardiopulmonary exercise testing (CPET) to investigate exercise capacity and its
association with spinal deformity in patients with congenital scoliosis.
METHODS: Sixty patients with congenital scoliosis who underwent preoperative
spinal radiography, PFT, and CPET were included from January 2014 to November
2017. The impact of thoracic spinal deformity and rib anomalies on pulmonary
function and physical capacity was investigated.
RESULTS: A significant deterioration in pulmonary function with increases in the
severity of the major thoracic curve was demonstrated by the forced expiratory
volume in 1 second (FEV1), forced vital capacity (FVC), and total lung capacity
(all p < 0.001). The ratio of FEV1 to FVC was similar regardless of thoracic
curve severity. A smaller tidal volume during exercise testing reflected
restrictive dysfunction in the patients with the most severe curves. CPET also
revealed a significant trend of faster breathing by patients with a severe
thoracic curve (p < 0.001). Exercise capacity indicators such as work rate (p =
0.019), heart rate (p = 0.015), and oxygen saturation (p = 0.006) were
significantly reduced only in patients with a thoracic curve of >100°. Pulmonary
dysfunction was the major contributor to exercise intolerance. Compared with mild
pulmonary dysfunction, moderate and severe dysfunction was associated with an
abnormal breathing pattern and lower work rate (p = 0.032) and peak oxygen intake
(p = 0.042), indicating worse exercise tolerance.
CONCLUSIONS: Congenital scoliosis leads to restrictive pulmonary dysfunction,
which reduces the tidal volume and forces patients to accelerate respiratory
rates during exercise. Patients with a thoracic curve of >100° are unable to
compensate and have significantly reduced exercise capacity.