The etiology and pathogenesis of adolescent idiopathic scoliosis (AIS) and congenital scoliosis are markedly different. Among the differences, progressive congenital scoliosis has the potential to cause much more severe impairment of pulmonary function than does AIS.
In an observational study in the June 19, 2019 issue of The Journal of Bone & Joint Surgery, Lin et al. investigate the precise extent to which pulmonary function and exercise capacity are affected by congenital scoliosis of varying severity. Sixty patients with congenital scoliosis (ranging from 10 to 39 years old) underwent spinal radiography, static pulmonary function testing (PFT), and dynamic cardiopulmonary exercise testing (CPET). From that data the researchers determined the impact of thoracic spinal deformity and rib anomalies on pulmonary function and exercise capacity.
Not surprisingly, PFT results, including total lung capacity, decreased as the severity of thoracic curves increased. In addition, patients with moderate or severe static pulmonary dysfunction had lower exercise tolerance than those with no or mild pulmonary dysfunction. CPET also revealed reduced ventilation capacity, faster respiratory rate, and smaller tidal volume in patients with more complex rib anomalies, although overall exercise tolerance did not differ among patients based on the severity of rib anomalies.
The authors observe that “although patients with thoracic deformities have the potential to compensate during increasing exercise,…exercise capacity (represented by work rate and maximal heart rate) declined greatly in patients with a thoracic curve exceeding 100°.” Because of the connection between congenital scoliosis with pronounced thoracic curves and loss of exercise capacity, Lin et al. recommend “early diagnosis, close follow-up, and timely treatment” for patients with this condition.