Surgical Outcomes Research

Study Design. Prospective study.

Objectives. To prospectively evaluate sequential pulmonary function tests (PFTs) at a minimum 2-year follow-up after an open anterior spinal fusion (ASF) with instrumentation for thoracic AIS.

Summary of Background Data. Anterior spinal fusion with instrumentation is currently undergoing evaluation as an alternative to posterior spinal fusion (PSF) for thoracic adolescent idiopathic scoliosis (AIS). However, the effect of an open thoracotomy on pulmonary function in these patients is unknown.

Methods. Fifty-one patients with thoracic AIS with an average age of 15+0 (range 11+2 to 20+5) had PFTs consisting of volume (FVC), flow (FEV-1), and total lung capacity (TLC). Parameters were obtained preoperatively, and at 3 months, 1 year, and a minimum 2-year follow-up. All patients had a single or double open thoracotomy with the diaphragm kept intact. Fusion levels ranged from T4 (most proximal) to L1 (most distal). The average preoperative thoracic coronal Cobb measurement was 53° (range 38° to 80°), and the average postoperative coronal measurement was 24° (range 7° to 49°). The average preoperative thoracic sagittal kyphosis (T5–T12) averaged 22° (range 10° to 58°), and the average postoperative sagittal kyphosis measured 29° (range 7° to 67°).

Results. There was a significant decline (P ≤0.05) in PFT absolute values (L) of 19%-FVC, 15%-FEV-1, and 11%-TLC at 3 months postoperatively with subsequent improvement and no statistical difference between preoperative and 2-year postoperative values. When evaluating percent predicted values, there was a statistical decline (P ≤0.05) at 3 months postoperatively averaging 19% FVC, 14% FEV-1, and 12% TLC. These values returned to within 94% to 96% of baseline by the 2-year follow-up visit, but were still statistically less than the preoperative values (P ≤0.05).

Conclusions. Pulmonary function following thoracotomy with ASF with instrumentation demonstrated a significant decline of 3-month postoperative PFT values, but returned to preoperative baseline absolute values (L) by the 2-year follow-up visit. The percent predicted values returned to within 95% of baseline 2 years postoperatively. Scoliosis surgeons should be aware of these findings when deciding upon the approach (anterior versusposterior) utilized for thoracic AIS.