Table 1.

Reference values for ligament material parameters. In the spring and FRPHE models, the adjusted values are the fibril network modulus values after matching the first peak of the tibiofemoral joint reaction force with the rest of the knee models.

Material formulation	ACL	PCL	MCL	LCL	PT	QT
Spring
Initial
k (Nmm−1)	201	258	114	134	545	475
Adjusted
k (Nmm−1)	100	129	57	67	545	475
Linear Elastic
E (MPa)	123	168	224	280	336	370
ν	0.4	0.4	0.4	0.4	0.4	0.4
Hyperelastic (Neo-Hookean)
C1 (MPa)	22	30	40	50	60	66
D (MPa−1)	0.005	0.0036	0.003	0.0021	0.002	0.002
Porohyperelastic
C1 (MPa)	22	30	40	50	60	66
D (MPa−1)	0.005	0.0036	0.003	0.0021	0.002	0.002
k0 (10−15 m4/Ns)	2.9	2.9	2.9	2.9	2.9	2.9
M	7.98	7.98	7.98	7.98	7.98	7.98
Fibril-reinforced porohyperelastic (FRPHE)
Initial
Ef (MPa)	130	180	270	280	184	380
Adjusted
Ef (MPa)	100	40	120	100	150	150
Unchanged values
Em (MPa)	1	1	1	1	10	10
νm	0.4	0.4	0.4	0.4	0.4	0.4
k0 (10−15 m4/Ns)	2.9	2.9	2.9	2.9	2.9	2.9
M	7.98	7.98	7.98	7.98	7.98	7.98
C	12	12	2	2	2	2

k_s = spring constant, E = Young’s modulus, ν = Poisson’s ratio, C₁ = material coefficient, D = compressibility coefficient, k₀ = initial permeability, M = exponential term for the strain-dependent permeability, E_m = nonfibrillar matrix modulus, E_f = fibril network modulus, ν_m = Poisson’s ratio of the nonfibrillar matrix, C = density ratio between primary and secondary fibrils.