Fig. 2From: Biomechanical comparison of multilevel lateral interbody fusion with and without supplementary instrumentation: a three-dimensional finite element studyConstruction of the disc model. a The constructed discs are composed of the nucleus pulposus (NP) and 56% annulus fibrosus (AF). b The collagen fibers that support the AF matrix were angled at 30 to 45° with respect to the horizontal plane and varied from the inner to outer lamina of the AFBack to article page