Biomechanical evaluation of the 3D printing brace for the lumbar spine

Purpose To evaluate the biomechanical effects of a customized 3D printing brace (3DP), comparing with standardized braces (Medi-H, Medi-S) in healthy adults. Methods Sixteen participants (13 females, three males) performed four tasks—static standing, trunk flexion, trunk extension, and pick-up, while wearing each brace. Interface pressure distribution was measured across seven regions—upper/middle/lower spine and erector spinae, and quadratus lumborum. Thoracic and lumbar range of motion (ROM) were simultaneously assessed from C7 to T8, and from T8 to L3. A repeated-measures ANOVA was used to examine the effects of braces. Results Both 3DP and Medi-H generated significantly higher overall pressures than Medi-S, which averaged only 60% of their values. In flexion and pick-up tasks, 3DP enhanced support at the middle regions but showed markedly reduced pressure in the lower region compared with Medi-H. 3DP provided greater support at the erector spinae regions, while Medi-H produced higher spinal pressures, especially during extension. Across all tasks, thoracic and lumbar ROM ranged between 20° and 30°, with no significant differences between the three braces, indicating that restriction of sagittal motion was comparable. Conclusion Within a similar restriction of both ROM, the 3DP provided superior biomechanical support at upper and middle support compared with standardized braces, but it requires further refinement in the lower regions.