Development and evaluation of an airbag brace system for idiopathic scoliosis subjects

There are disadvantages, especially from biomechanical viewpoint, to treating idiopathic scoliosis (IS) patients using traditional Boston braces with pressure pads. The major problem is the higher stiffness of the pressure pad as compared to the soft-tissue of the trunk. The aim of this study was to evaluate the effectiveness of Boston braces in which the pressure pad was replaced by the deformable airbag. A custom-made airbag brace which was designed based on the three-point compression principle of the Boston brace was prescribed to each of the 20 IS subjects with a mean age of 11.8 ± 2.8 years old. To evaluate the effectiveness of the treatment, the scoliosis Cobb angles before the treatment and after a follow-up period were measured from AP X-rays. The mean follow-up period was 11.5 ± 6.6 months. In addition, three interface parameters -contact pressure, contact area, and contact force -under seven postures -upright, flexion, extension, left side bending, right side bending, left side rotation and right side rotation -were measured using pressure mats to investigate interface conditions between airbags and skin. During the follow-up, all scoliosis curves showed Cobb angle reduction except one thoracic curve, which increased by one degree. The Cobb angle in the thoracic region decreased from 37.3 ± 10.6° to 27.3 ± 10.1° with a mean decreasing of 9.9 ± 5.9°. The Cobb angle in the lumbar region decreased from 30.1 ± 6.9° to 17.7 ± 8.6° with a mean decreasing of 12.4 ± 4.9°. Changes in the three interface parameters for the seven postures were insignificant. This indicated that the airbag brace could provide sufficient continuous corrective force. Using the airbag, instead of the pressure pad to provide the corrective force in the brace system can effectively correct the spinal curve caused by scoliosis. Easy adjustment and direct control of airbag pressure might be the key factor to the success of the airbag brace.