[Pulmonary function changes after operation in patients with severe scoliosis]

To evaluate pulmonary function changes in patients with severe scoliosis undergoing anterior release, posterior segmental fixation and fusion, and convex thoracoplasty by resecting a short length of rib.

From January 2006 to July 2007, 16 patients with severe scoliosis were treated with anterior release, posterior segmental fixation and fusion, and convex thoracoplasty by resecting a short length of rib. There were 6 males and 10 females with an average age of 16.9 years (range, 10-24 years). There were 1 case of Lenke 1 curve, 9 cases of Lenke 2 curve, and 6 cases of Lenke 4 curve. The preoperative Cobb angle was (104.8 +/- 10.9) degrees and the preoperative thoracic kyphotic angle was (30.0 +/- 4.2) degrees. The preoperative height of "razor back" deformity was (5.9 +/- 1.2) cm. Before operation, the actual value of forced vital capacity (FVC) was (2.04 +/- 0.63) L and that of forced expiratory volume in 1 second (FEV1.0) was (1.72 +/- 0.62) L. The percentage of actual values to expected ones in FVC was 70% +/- 16%, and that in FEV1.0 was 67% +/- 15%. All patients had pulmonary function tests before operation and 3, 6, 12, 24 months after operation.

All wounds healed by first intention. The Cobb angle at 24-month follow-up was (53.4 +/- 18.6) degrees and the correction rate was 49.0% +/- 15.3%. The thoracic kyphotic angle at 24-month follow-up was (34.0 +/- 2.4) degrees and the correction rate was 13.3% +/- 2.2%. The height of "razor back" deformity at 24-month follow-up was (2.2 +/- 0.8) cm. Compared with preoperative level, all these data showed significant differences (P < 0.05). At 3 and 6 months, the actual values of FVC and FEV1.0 declined, but no significant difference was found (P > 0.05). At 12 and 24 months, the actual values of FVC and FEV1.0 were close to the preoperative level (P > 0.05). The percentages of actual values to expected ones in FVC and FEV1.0 indicate continued improvement in pulmonary function from the postoperative 3 to 24 months follow-up. Compared with preoperative level, the percentages of actual values in FVC declined 19% 3 months postoperatively (P < 0.05) and 12% 6 months postoperatively (P < 0.05). The percentages of actual values to expected ones in FEV1.0 declined 16% 3 months postoperatively (P < 0.05), and 10% 6 months postoperatively (P < 0.05). The percentages of actual values to expected ones in FVC and FEV1.0 were close to the preoperative level 12 and 24 months after operation (P > 0.05).

In severe scoliosis patients who are treated with anterior release, posterior segmental fixation and fusion, and convex thoracoplasty by resecting a short length of rib, pulmonary function decreases obviously 3-6 months after operation. And it returns to the operative baseline 12-24 months after operation.