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Posterior Spinal Fusion for Scoliosis in Duchenne Muscular Dystrophy Diminishes the Rate of Respiratory Decline

Velasco, Maria V., MD*; Colin, Andrew A., MD*; Zurakowski, David, PhD; Darras, Basil T., MD; Shapiro, Frederic, MD

doi: 10.1097/01.brs.0000255062.94744.52
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Study Design. To assess the rate of decline in pulmonary function in Duchenne muscular dystrophy (DMD) before and after posterior spinal fusion for scoliosis.

Objective. To compare the rate of respiratory decline using percent normal forced vital capacity (%FVC) measurements before and after posterior spinal fusion.

Summary of Background Data. Posterior spinal fusion for scoliosis is used widely in DMD, although the long-term pulmonary effects have not been well established.

Methods. Fifty-six patients were assessed. Percent forced vital capacity was the outcome parameter with data analysis using a mixed-model repeated-measures ANOVA and paired t tests. Group 1: Inclusion criteria were a diagnosis of DMD, 2 or more pulmonary function tests presurgery, and 2 or more postsurgery. Group 2: The rates of respiratory decline before and after spinal fusion for the whole study population were determined by within- subjects mixed-model regression analysis to account for the varying number of FVC studies between patients and unequal spacing between tests.

Results. Group 1: 20 patients. Mean length of time of respiratory value determination was 2.5 ± 1.0 years presurgery and 5.6 ± 2.8 years postsurgery. Mean rate of decline presurgery was 8.0% ± 4.1% per year, which decreased to 3.9% ± 1.9% per year postsurgery (paired t test = 4.58, P < 0.0001). Group 2: 56 patients. The respiratory value determinations ranged from 4 years presurgery to 8 years postsurgery. The rates of respiratory decline based on the whole study population were 4% per year presurgery, which decreased to 1.75% per year postsurgery (F-test comparison of slopes = 19.71, P < 0.0001).

Conclusions. Posterior spinal fusion for scoliosis in DMD is associated with a significant decrease in the rate of respiratory decline postsurgery compared with presurgery rates.

Posterior spinal fusion for scoliosis in DMD is associated with a significant decrease in the rate of respiratory decline postsurgery compared with presurgery rates. In 20 patients with at least 2 PFTs presurgery and 2 postsurgery, the %FVC decreased from 8% per year to 3.9%. In 56 patients, with a variable number of studies, mixed-model regression analysis showed a decline from 4% presurgery to 1.75% postsurgery.

From the Departments of *Medicine (Division of Respiratory Diseases), †Orthopaedic Surgery, and ‡Neurology, Children's Hospital Boston and Harvard Medical School, Boston, MA. Drs. Velasco and Colin contributed equally to this work. The current affiliation of Dr. Velasco is Department of Pediatrics, Hospital Universitario de Canarias, Tenerife, Spain. The current affiliation of Dr. Colin is Division of Pediatric Pulmonology, Miller School of Medicine, University of Miami, Miami, FL.

Acknowledgment date: February 27, 2006. First revision date: May 8, 2006. Acceptance date: May 11, 2006.

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

No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Frederic Shapiro, MD, Department of Orthopaedic Surgery, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115; E-mail: frederic.shapiro@childrens.harvard.edu

© 2007 Lippincott Williams & Wilkins, Inc.