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.