A biomechanical comparison between the thoracolumbosacral surface contact area (SCA) of a standard backboard with other rigid immobilization surfaces.

INTRODUCTION Backboards are routinely used to protect the spine of trauma patients during transportation. Nevertheless, little is known about the biomechanical properties of this type of immobilization. OBJECTIVES To evaluate the mechanical support of the thoracolumbosacral spine provided by a standard backboard in comparison with various rigid immobilization surfaces, by examining their respective surface contact area (SCA). MATERIALS SCAs comparisons of a standard aluminum backboard, a rigid military stretcher, an aluminum backboard covered by blanket, 3 and 5 cm thickness foam, and a cushioned stretcher were made using 12 volunteers. The evaluation was performed by a computer- mediated system that generated a diagram indicating pressure distribution and SCA score in each volunteer. These data were compared with a medical grade mattress, which served as the control group. RESULTS The median backboard's SCA was 14.6 +/- 5.5 times smaller than the stretcher's SCA (range 4.6-28, average 15, p < 0.001). Its median SCA was essentially doubled by covering it by a standard military blanket and tripled when covered by 3 cm layer of foam. Using a 5-cm layer of foam increased the backboard's SCA by 11 times. Cushioning the stretcher beneath the lumbar spine and the hamstrings by folded blankets, significantly improved its median SCA (96 +/- 31.1, range 36-125, average 89.7). CONCLUSIONS The backboard's SCA was significantly inferior to all the other surfaces. Although no dynamic evaluation was performed, these data imply that backboards need to be appropriately cushioned or alternate surfaces should be employed to improve the mechanical support during trauma patient transportation. Level of evidence, Level I.