A Constitutive Model for the Annulus of Human Intervertebral Disc: Implications for Developing a Degeneration Model and Its Influence on Lumbar Spine Functioning

Table 1

Material properties of the reference case [40].

Material parameters	Input value	Description
𝑐𝐹,0 [meq/mm^3]	2.0×10^−4	Initial fix charge density
𝑐ext [mmol/mm^3]	1.5×10^−4	Initial external salt concentration
𝑐^∗ [mmol/mm^3]	1.0×10^−4	External salt concentration at 𝑡=0
𝑘0 [m^4/Ns]	1.0×10^−15	Initial permeability
𝑛𝑓,0	0.75	Initial fluid fraction