Early changes in pulmonary function following thoracotomy for scoliosis correction: the effect of size of incision

It is generally believed that minimal access surgery may produce less change in pulmonary function than conventional open thoracotomy for scoliosis correction. Though there is considerable literature regarding changes in pulmonary function tests (PFT) after thoracotomy, there is scant data available regarding the effect of the magnitude of thoracic wall disruption on pulmonary function, particularly in the early postoperative weeks. This study aims to evaluate the effect of the size of incision on pulmonary function after anterior release and fusion in patients with moderate thoracic curves due to adolescent idiopathic scoliosis. The study group was made up of 19 patients with thoracic curves due to adolescent idiopathic scoliosis. The subjects had had thoracotomy for anterior release, followed by posterior instrumentation and fusion at a second sitting. The ten patients who had had conventional, large thoracotomy were placed in group A and the nine minimal access cases in group B. PFTs consisting of volume (FVC) and flow (FEV1) were obtained before the anterior release, 2 weeks later (before the posterior instrumented fusion), and 3 months after the posterior fusion. The degree of deformity in the sagittal and the coronal plane preoperatively and postoperatively were measured and documented. The mean preoperative pulmonary function was significantly less than the predicted values for both patient groups. There was a decline in the postoperative pulmonary function (both percentage predicted value and absolute value) in both groups at 2 weeks and at 3 months. The deterioration of pulmonary function was less in the small-thoracotomy group, but this difference between the groups was statistically significant only for the 2-week values. Our study shows that there is significant pulmonary function restriction even in patients with moderate thoracic curves. There was a lesser decline in pulmonary function in the minimal-access group, as compared with the standard thoracotomy group, but this difference was only in the early postoperative period and became insignificant by 3 months.