Fig. 1.

a Patient-specific, three-dimensional, L4–L5 MBS model, based on CT data including spinal ligaments (blue lines): ligamentum longitudinale anterius (ALL), ligamentum longitudinale posterius (PLL), ligamentum flavum (FL), ligamenta intertransversaria (ITL), ligamenta capsularia (CL), ligamentum interspinale (ISL), and ligamentum supraspinale (SSL). Big black dots indicate the centers of mass of the single vertebrae. Gray area represents the frontal plane that is dividing the body in a ventral and dorsal part and in our configuration lies parallel to the x–z-plane. b An example representation of the intervertebral disk (see Sect. 2.2.2), which acts as a force- and torque-transmitting joint (six degrees of freedom) between each pair of vertebrae