Does early thoracic fusion exacerbate preexisting restrictive lung disease in congenital scoliosis patients?

BACKGROUND: Congenital thoracic scoliosis is associated with diminished pulmonary function. Early posterior thoracic spinal fusion surgery may additionally impact pulmonary function beyond the natural history of the disease by further inhibiting thoracic growth. The primary study aim is to determine if early thoracic spine fusion patients have diminished pulmonary function versus untreated patients at a similar age. The secondary study aim is to determine how plain radiographic measurements of thoracic deformity change over time and correlate to pulmonary function in these patients.

METHODS: Sequential spinal radiographs and one-time pulmonary function tests were performed in 43 consecutive congenital thoracic scoliosis patients with either a history of early posterior thoracic fusion or no surgery. Multiple stepwise t testing compared the patient-related and radiographic variables in the early surgery and no surgery groups. Multiple stepwise linear regression analysis examined the effect of the variables at final follow-up on forced vital capacity and forced expiratory volume.

RESULTS: All patients exhibited decreased forced vital capacity, but there was no difference between early surgery and no surgery groups at an average follow-up age of 10.5 years. A mid- (versus low) thoracic apex, decreased space available for the lung, and decreased age-corrected thoracic width correlated with decreased forced vital capacity. Between initial and final radiographic follow-up, the rate of change in thoracic height and width was decreased in the early surgery versus no surgery group.

CONCLUSIONS: Early posterior spinal fusion decreases radiographic measures of thoracic growth over time, but pulmonary function was similar to untreated patients at 10.5 years of age. The data suggest pulmonary function and thoracic size as measured on plain radiographs correlate directly. Therefore, pulmonary function testing at the end of growth should be performed to determine the ultimate pulmonary consequences of early surgery.