Direct Osmotic Pressure Measurements in Articular Cartilage Demonstrate Nonideal and Concentration-Dependent Phenomena.

Autor:	Zimmerman BK; Department of Mechanical Engineering, Columbia University, New York, NY 10027., Nims RJ; Department of Biomedical Engineering, Columbia University, New York, NY 10027., Chen A; Department of Mechanical Engineering, Columbia University, New York, NY 10027., Hung CT; Department of Biomedical Engineering, Columbia University, New York, NY 10027., Ateshian GA; Department of Mechanical Engineering, Columbia University, New York, NY 10027; Department of Biomedical Engineering, Columbia University, New York, NY 10027.
Jazyk:	angličtina
Zdroj:	Journal of biomechanical engineering [J Biomech Eng] 2021 Apr 01; Vol. 143 (4).
DOI:	10.1115/1.4049158
Abstrakt:	The osmotic pressure in articular cartilage serves an important mechanical function in healthy tissue. Its magnitude is thought to play a role in advancing osteoarthritis. The aims of this study were to: (1) isolate and quantify the magnitude of cartilage swelling pressure in situ; and (2) identify the effect of salt concentration on material parameters. Confined compression stress-relaxation testing was performed on 18 immature bovine and six mature human cartilage samples in solutions of varying osmolarities. Direct measurements of osmotic pressure revealed nonideal and concentration-dependent osmotic behavior, with magnitudes approximately 1/3 those predicted by ideal Donnan law. A modified Donnan constitutive behavior was able to capture the aggregate behavior of all samples with a single adjustable parameter. Results of curve-fitting transient stress-relaxation data with triphasic theory in febio demonstrated concentration-dependent material properties. The aggregate modulus HA increased threefold as the external concentration decreased from hypertonic 2 M to hypotonic 0.001 M NaCl (bovine: HA=0.420±0.109 MPa to 1.266±0.438 MPa; human: HA=0.499±0.208 MPa to 1.597±0.455 MPa), within a triphasic theory inclusive of osmotic effects. This study provides a novel and simple analytical model for cartilage osmotic pressure which may be used in computational simulations, validated with direct in situ measurements. A key finding is the simultaneous existence of Donnan osmotic and Poisson-Boltzmann electrostatic interactions within cartilage. (Copyright © 2021 by ASME.)
Databáze:	MEDLINE
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