Analysis of Changes in Spinal and Pelvic Parameters when Optimally Seated on an Automotive Seat Compared to Standing

PURPOSE: The comfort of a seat in a seated posture has been reported to be affected by the alignment of the spine and pelvis in a standing posture when designing an automotive seat. Therefore, in order to find items to improve vehicle seat comfort performance, this study was conducted to measure the change in spinopelvic parameter values according to a change from a standing posture to a seat sitting posture and to reflect them in the design of vehicle seats to improve comfort.METHOD: X-ray data for 15 participants was measured and analyzed while standing and sitting in the optimal posture on an automotive seat. Cervical lordosis angle, thoracic kyphosis angle, lumbar lordosis angle, sacral inclination angle, and C7-SVA (sagittal vertical axis) were measured.RESULTS: Compared to standing, there were no statistically significant changes in the cervical lordosis and thoracic kyphosis angles when sitting in the car seat in the optimal posture, but only the lumbar lordosis changed (from 32.13° ± 8.356° to 6.568° ± 3.048°, p<0.0001). Cervical lordosis varied from 12.78° ± 8.15 to 12.58° ± 9.14° and thoracic kyphosis from 30.34° ± 8.10° to 31.6° ± 9.48° when standing and sitting in an optimal posture, but there was no statistical significance. However, the lumbar lordosis decreased from 32.13° ± 8.36° to 6.57° ± 3.05° and the sacral inclination angle decreased from 27° ± 11.13° to -21.79° ± 6.48°, respectively, and both were statistically significant in the paired t-test (p< 0.0001, p<0.0001, respectively). In the case of C7-SVA, there was a statistically significant change from 22.26 ± 15.17mm to 94.23 ± 46.14mm (p=0.0007). Except for the differences in the cervical lordosis angle change and the thoracic kyphosis angle change, there were statistically significant differences in standing and sitting conditions.CONCLUSION: As a result of this study, the changes in lumbar lordosis angle, sacral inclination angle, and C7-SVA were greater when sitting on a seat than when standing. This is related to the performance of comfort when sitting on a seat, and this data is expected to be used as useful data for designing seat shapes and lumbar support when developing seat designs in the future.