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Scoliosis Surgery in Patients With Adolescent Idiopathic Scoliosis Does Not Alter Lung Volume: A 3-Dimensional Computed Tomography–Based Study

Sarwahi, Vishal MD*; Sugarman, Etan P. MD*; Wollowick, Adam L. MD*; Amaral, Terry D. MD*; Harmon, Elliot D. BS*; Thornhill, Beverly MD

doi: 10.1097/BRS.0000000000000203
Deformity
SLIDE

Study Design. Retrospective study of surgically treated patients with adolescent idiopathic scoliosis.

Objective. To determine the change in lung volume after the surgical correction of scoliosis using a volumetric reconstruction of lung volume from computed tomographic (CT) scans.

Summary of Background Data. Previously published studies have shown that pulmonary function tests improve after scoliosis correction; however, these results are not consistent. CT-based volumetric studies in patients with scoliosis have previously shown differences in lung volume and lung volume ratio when compared with a normal population. To date, no study exists that analyzes changes in these parameters after scoliosis surgery.

Methods. A total of 29 patients with adolescent idiopathic scoliosis who had pre- and postoperative CT scans on file were included in this study. Three-dimensional lung volume reconstruction was performed (TeraRecon software, TeraRecon, Inc., Foster City, CA). Appropriate masking methods were used to isolate the lung tissue. Total lung volumes, left and right lung volumes, and left/right lung volume ratio were obtained from the pre- and postoperative CT scans. Hemithoracic symmetry, pre- and postoperative Cobb angle, and kyphosis were also calculated.

Results. Neither total lung volume nor left/right lung volume ratio changed significantly postoperatively. Surgery did not significantly change total lung volume (P = 0.87), right lung volume (P = 0.69), left lung volume (P = 0.70), or the ratio between right and left lung volumes (P = 0.87). Hemithoracic asymmetry was significantly improved (P < 0.001). Median preoperative major Cobb angle was 53.2° and median preoperative kyphosis was 32.8°. Postoperatively, the median major Cobb angle was 15.0°, resulting in a 70% Cobb correction, and mean postoperative kyphosis was 31.1°.

Conclusion. Corrective scoliosis surgery does not alter total lung volume or the ratio of right-to-left lung volume. Deformity correction leads to an improvement in the symmetry of the thoracic architecture and costovertebral joint mechanics, as evidenced by the improved hemithoracic asymmetry. Thus, the change in pulmonary function tests, which has been previously documented, may be a dynamic rather than a static phenomenon.

Level of Evidence: 4

Computed tomography–based volumetric measurement can be used to assess lung volume. Total lung volume and the ratio of right-to-left lung volume did not change after scoliosis correction. This study suggests that improvement of pulmonary function after scoliosis surgery may be due to normalization of chest wall mechanics and symmetry.

*Departments of Orthopaedic Surgery; and

Radiology, Montefiore Medical Center, The Albert Einstein College of Medicine, Bronx, New York, NY.

Address correspondence and reprint requests to Vishal Sarwahi MD, Department of Orthopaedic Surgery, Albert Einstein College of Medicine, 3400 Bainbridge Ave, 6th Floor, Bronx, NY 10467; E-mail: VSARWAHI@montefiore.org

Acknowledgment date: July 24, 2012. First revision date: October 19, 2013. Second revision date: December 18, 2013. Acceptance date: December 19, 2013.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work.

Relevant financial activities outside the submitted work: consultancy, grants, payment for lecture.

© 2014 by Lippincott Williams & Wilkins