Superficial Collagen Fibril Modulus and Pericellular Fixed Charge Density Modulate Chondrocyte Volumetric Behaviour in Early Osteoarthritis

Table 2

Parameters implemented in the parametric fibril reinforced poroelastic swelling models. Parametric analyses were conducted by varying one parameter, while the other parameters were kept constant. CNTRL: contralateral, ACLT: anterior cruciate ligament transected.

Model	Collagen stiffness (𝐸𝑓) (MPa)			Fixed charge density (𝑐𝐹) (mEq/mL)			Fluid fraction (𝑛𝑓)
	ECM	PCM	Cell	ECM	PCM	Cell	ECM	PCM	Cell
Experimental loading protocol^†:
CNTRL model	Table 1	Table 1	Table 1	Table 1	Table 1	Table 1	Table 1	Table 1	Table 1
ACLT model	7.5	0.1×𝐸^ECM𝑓	Table 1	0.08+0.12𝑧	0.11+0.09𝑧	Table 1	0.9−0.2𝑧	0.90	Table 1
Parametric CNTRL PCM; model	Table 1	[0.01,1]×𝐸^ECM𝑓	Table 1	Table 1	[0.02,0.18]	Table 1	Table 1	[0.50,0.95]	Table 1
Parametric ACLT PCM; model	7.5	[0.01,1]×𝐸^ECM𝑓	Table 1	0.08+0.12𝑧	[0.02,0.18]	Table 1	Table 1	[0.50,0.95]	Table 1
Parametric ECM model	[7.5,10]	0.1×𝐸^ECM𝑓	Table 1	**	Table 1	Table 1	[0.50,0.90]	Table 1	Table 1
Constant strain:
Parametric ECM model	[2.5,10]	0.1×𝐸^ECM𝑓	Table 1	**	Table 1	Table 1	[0.50,0.90]	Table 1	Table 1
Parametric PCM model 1	Table 1	[0.01,1]×𝐸^ECM𝑓	Table 1	Table 1	[0.02,0.18]	Table 1	Table 1	[0.50,0.95]	Table 1
Parametric PCM model 2	7.5	[0.01,1]×𝐸^ECM𝑓	Table 1	Table 1	[0.02,0.18]	Table 1	Table 1	[0.50,0.95]	Table 1
Parametric PCM model 3	5.0	[0.01,1]×𝐸^ECM𝑓	Table 1	Table 1	[0.02,0.18]	Table 1	Table 1	[0.50,0.95]	Table 1
Parametric PCM model 4	2.5	[0.01,1]×𝐸^ECM𝑓	Table 1	Table 1	[0.02,0.18]	Table 1	Table 1	[0.50,0.95]	Table 1

^†In the experimental loading protocol the strain was kept constant after a loading stress of 2 MPa was reached.
**In the parametric ECM model 5 different depth-dependent FCD distributions were implemented (𝑐_𝐹=0.011 + 0.009𝑧,𝑐_𝐹=0.06 + 0.045𝑧,𝑐_𝐹=0.11+0.09𝑧,𝑐_𝐹=0.165+0.135𝑧, and 𝑐_𝐹=0.22+0.18𝑧). 𝑧 is normalized cartilage depth (0 = surface, 1 = bottom).