1. Cationic agent contrast-enhanced computed tomography imaging of cartilage correlates with the compressive modulus and coefficient of friction 
B.A. Lakin, D.J. Grasso, S.S. Shah, R.C. Stewart, P.N. Bansal, J.D. Freedman, M.W. Grinstaff, B.D. Snyder 
Osteoarthritis and Cartilage 
Volume 21, Issue 1, Pages (January 2013)
DOI: /j.joca
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

2. Fig. 1
(A) Photos showing locations where osteochondral plugs were harvested from bovine patellae, femoral grooves, and femoral condyles. Plugs were randomly selected after freezing. (B) Schematic of mechanical testing setup. A – frame of machine, B – plug fixture with set screws to anchor plug by its subchondral bone, C – 7 mm diameter osteochondral plug, D – physiologic saline, E – aluminum platen, F – torque cell, G – load cell, H – actuator. Each osteochondral plug from both groups was subjected to a four-step compression against the aluminum platen while immersed in saline. Plugs from Group 2 were also subjected to a 720° rotation following the 45-min relaxation after the final compressive step.
Osteoarthritis and Cartilage  , 60-68DOI: ( /j.joca )
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

3. Fig. 2
Correlations between CECT attenuation (HU) and GAG content (mg/mg) of cartilage samples for (A) CECT vs E samples (Group 1, unfilled data points indicate degraded samples) and (B) CECT vs μ samples (Group 2). Both correlations were strong (coefficients of variation greater than or equal to 0.74) and statistically significant (P ≤ 0.001). Color maps of representative, non-degraded samples with (C) low (2.86%) and (D) high (4.88%) GAG contents.
Osteoarthritis and Cartilage  , 60-68DOI: ( /j.joca )
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

4. Fig. 3
Correlations between (A) equilibrium compressive modulus (E) (MPa) and GAG content and (B) CECT attenuation (HU) and equilibrium compressive modulus (E) (MPa) for Group 1 (unfilled data points indicate degraded samples). Both correlations were strong (coefficients of variation equal to 0.90) and statistically significant (P < 0.0001).
Osteoarthritis and Cartilage  , 60-68DOI: ( /j.joca )
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

5. Fig. 4
Correlations between CECT attenuation (HU) and three different experimentally-determined coefficients of friction (μ): (A) μstatic, (B) μstatic_equilibrium, (C) μkinetic for Group 2.
Osteoarthritis and Cartilage  , 60-68DOI: ( /j.joca )
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

6. Fig. 5
Correlations between GAG content of each sample and three different experimentally-determined coefficients of friction (μ): (A) μstatic, (B) μstatic_equilibrium, (C) μkinetic for Group 2.
Osteoarthritis and Cartilage  , 60-68DOI: ( /j.joca )
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

7. Fig. 6
Correlations between CECT attenuation (HU) excluding the STZ of each sample and three different experimentally-determined coefficients of friction (μ): (A) μstatic, (B) μstatic_equilibrium, (C) μkinetic for Group 2.
Osteoarthritis and Cartilage  , 60-68DOI: ( /j.joca )
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions