This study will be conducted without blind method. The portable seat device devised to maintain lumbar lordosis will be made within 1 year after the loss of ambulation in the participants with Duchenne muscular dystrophy with prospective design.

In the control group, the presence of scoliosis will be calculated 5 years after the loss of ambulation in participants with Duchenne muscular dystrophy through analysis of retrospective medical records who had not been applied the portable seat device.

In the retrospective data of Seoul National University Children's Hospital, the incidence of 5-year scoliosis in the control group in the past using steroids alone was 70% in patients with confirmed Duchenne muscular dystrophy. When applying the portable seat device (experimental group), the incidence of scoliosis is expected to decrease to 50% (ie, 35% because of 50% of 70%) compared with using steroid alone.

In this study, investigators will enroll 70 control subjects who did not use the portable seat device through retrospective data. The number of subjects required to show the difference between the significance level of 5% and the power of 80% was 19, and 28 participants with DMD are required considering 30% dropout rate.

Inclusion Criteria:

• Patients with the diagnosis of Duchenne muscular dystrophy diagnosed by genetic study were included.

  1. Within 1 year after loss of ambulation (Vignos scale 7 points or more)
  2. Condition without scoliosis
  3. Conditions that do not have physical (eg, cerebral palsy) and mental (eg, moderate or higher intellectual disability) comorbid conditions that will affect the use of postural seat device.

Exclusion Criteria:

1. Patients who do not agree to participate in this study
2. Patients not taking steroids
3. Patient with scoliosis