Beyond the classic correction system: a numerical nonrigid approach to the scoliosis brace

Adolescent idiopathic scoliosis (AIS) causes a spine and rib cage three-dimensional (3D) deformity previously treated by bracing. Whatever the manufacturing process, this rigid system acts biomechanically on the patient through the "three-point bending" mechanical principle. It applies corrective forces to a limited area and acts especially in the frontal plane. It seemed to us that a nonrigid system, called "Cbrace," with 3D action allowing distribution of forces could increase compliance and provide better long-term correction prospects.

The aim of this study was to design a nonrigid brace by numerically testing in a finite-element model developed here.

A finite-element model has been developed to simulate brace effect on AIS right thoracic deformation of a 10-year-old patient.

A two-step method was needed; first, the reliability of our model is evaluated, and then, the ability to use distributed forces to correct scoliosis deformation is tested. To obtain a 3D correction, several treatments are experimented, leading to a comparison test between the best combination to the "three-point bending" principle.

The numerical model developed here shows good qualitative answers for the treatment of brace forces. The first results demonstrate numerically that distributed forces may be of interest in brace treatment design. Overall force of 40 N above cartilage of the last nonfloating ribs associated to two posterior asymmetrical areas appears to be the best way to correct scoliosis deformation with nonrigid action.

The results show numerical efficacy of distributed forces to correct spinal deformities and raises the prospect that a new numerical brace, called "Cbrace," could be a starting point in the search for a nonrigid system.