1. Date of download: 1/6/2018
Copyright © ASME. All rights reserved.
From: Effect of Hydration on Healthy Intervertebral Disk Mechanical Stiffness
J Biomech Eng. 2015;137(10): doi: /
Figure Legend:
(a) Osmolality for each saline group. Osmolality increased linearly with PBS concentration (slope = 1851 mOsm/kg/M). (b) Percent change in saline osmolality after tissue swelling experiment (c) Swelling ratio was negatively correlated with the external osmotic environment (Pearson's: ρ < −0.55, p ≤ 0.001). Inset: Representative disk showing location and size of NP and AF tissue cores. * represents significant differences between the NP and AF swelling ratio at each osmotic condition (t-test, p < 0.01). (d) Swelling ratio normalized by the swelling ratio of the 0.15 M PBS group showed no significant differences between NP and AF explants (t-test: p = 0.4).

2. Date of download: 1/6/2018
Copyright © ASME. All rights reserved.
From: Effect of Hydration on Healthy Intervertebral Disk Mechanical Stiffness
J Biomech Eng. 2015;137(10): doi: /
Figure Legend:
(a) Residual stress from applied osmotic loading condition with respect to the estimated residual stretch (least-squares curve fit, R2 > 0.999). (b) Hydration correlated with residual stretch (Pearson correlation: NP: r = −0.99, p = 0.0001, AF: r = −0.88, p = 0.1). Values for 0.15 M PBS group are shown on each figure by the respective data point.

3. Date of download: 1/6/2018
Copyright © ASME. All rights reserved.
From: Effect of Hydration on Healthy Intervertebral Disk Mechanical Stiffness
J Biomech Eng. 2015;137(10): doi: /
Figure Legend:
(a) Representative sample in MTS device. Inset: Motion segments were potted in bone cement to ensure parallel-loading surfaces, and then placed in a saline bath (osmotic concentration range = 0.015 M to 3.0 M PBS) for mechanical testing. (b) Force–displacement curves from a representative motion-segment. Disk joint stiffness increased with an increase in saline osmolality. The dashed and solid red lines represent the toe- and linear-regions, respectively.

4. Date of download: 1/6/2018
Copyright © ASME. All rights reserved.
From: Effect of Hydration on Healthy Intervertebral Disk Mechanical Stiffness
J Biomech Eng. 2015;137(10): doi: /
Figure Legend:
Stiffness measured from slow ramp compression to 1000 N. (a) Overall displacement measured during compression tests, normalized by the displacement measured in the 0.15 M PBS group. (b) Toe- and (c) linear-region moduli with respect to the saline concentration. The mechanical behavior with respect to saline concentration can be described using the equations provided in the figure. All parameters demonstrated a moderate significant correlation with osmotic loading (Pearson's: p < 0.01).

5. Date of download: 1/6/2018
Copyright © ASME. All rights reserved.
From: Effect of Hydration on Healthy Intervertebral Disk Mechanical Stiffness
J Biomech Eng. 2015;137(10): doi: /
Figure Legend:
Average creep response under (a) 200 N and (b) 1000 N load. Differences in stiffness and time constant, as determined by a rheological model, are reported in Table 1.

6. Date of download: 1/6/2018
Copyright © ASME. All rights reserved.
From: Effect of Hydration on Healthy Intervertebral Disk Mechanical Stiffness
J Biomech Eng. 2015;137(10): doi: /
Figure Legend:
Rate-dependent change in apparent modulus measured during slow-ramp compression (0.55 N/s) and during the ramp to apply 1000 N for creep (40 N/s). (a) Toe-region apparent modulus was not rate dependent. (b) The linear-region apparent modulus increased by twofold with an increase in loading rate (* represents t-test p < 0.01). Data is presented as mean ± standard deviation.