Considering the inferior surface area of lower lumbar vertebrae: determining weight transmission pattern at the lumbosacral junction.

The biomechanical function of the lumbosacral junction (LSJ) is obscure, but its medical significance is not, as it is the most common site of low back pain. In this study, we analyzed the difference between the mean values of the surface areas of the inferior body and total inferior facet areas of the fourth and fifth lumbar vertebrae. We aimed to define the function of the LSJ during weight transmission and clarify its mechanical significance.