Displacements in (a) radial and (b) axial directions within the IVD under static compression with 50% permeable endplate boundary above the nucleus. Displacements were normalized by the half height of the disk (h0). (c) Radial distributions of normalized fluid pressure (at z^ =1) in the IVDs with different endplate boundary conditions at the first peak of the first cycle of sinusoidal loading (f=0.1 Hz, u1=5% of disc height). The fluid pressure (p) is normalized by p/(RTc*), where R is universal gas constant, T is absolute temperature, and c* is the concentration of saline (i.e., c*=0.15 M) (Huang and Gu, 2007).