Fig. 4.

IVD torque–angle characteristics from fitting Eq. (3) (solid lines) to modeled data of our L4–L5 unit (dashed polygonal chain) recreating the penultimate reduction step (w/o ALL) from Heuer et al. (2007). Note that (i) due to vertebral asymmetry flexion and extension are modeled separately, (ii) a third-order polynomial formulation would neither account for the three visible inflection points nor the appearing torque saturation, and (iii) the angles are given in degrees, although calculations were conducted using radians. For the corresponding parameter values, see Table 1