Design and validation of transducers to measure interface force distribution in a spinal orthosis

Scoliosis is a spinal deformity that affects millions of adolescents in the United States. Bracing is the most common non-surgical treatment method for scoliosis, but the biomechanics of such treatment is unclear. The objective of this study is to develop and validate a force logging system that can record forces at multiple locations inside a brace, as well as brace strap tension, and correlate these forces with different body positions. The force logging system can be used to investigate the biomechanics function of a brace to treat scoliosis during the treatment period. Two phases were completed in this study: design phase, involving custom development and calibration of strap tension transducers and modifications of in-brace force transducers; and validation phase, including preliminary testing on a subject with different postures. In-brace force load cell and tension transducer were tested and validated. Their sensitivities were 193.5±4.9mV/N and 35.5±0.2mV/N, respectively, with both linear correlation coefficients were 0.99, reflecting high repeatability and linearity. Qualitative validation was also completed, allowing general relationships to be found between subject posture and force distribution. This study shows an excellent functionality and utility of the developed system.