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The Mechanism of Synovial Fluid Retention in Pressurized Joint Cavities
Author(s) -
LU Y.,
LEVICK J. R.,
WANG W.
Publication year - 2005
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1080/10739680500253527
Subject(s) - synovial fluid , concentration polarization , chemistry , osmotic pressure , synovial joint , polarization (electrochemistry) , ultrafiltration (renal) , chromatography , materials science , membrane , medicine , pathology , biochemistry , alternative medicine , osteoarthritis , articular cartilage
Objective: Hyaluronan (HA) in synovial fluid is vital to fluid retention in joint cavities. This study aims to evaluate a HA concentration polarization hypothesis and to examine, quantitatively, the agreement between theoretical predictions and experimental results. Methods: A non‐steady‐state model was developed for HA ultrafiltration and concentration polarization on the synovial surface. The Kedem‐Katchalsky equation was used to calculate the trans‐synovial filtration rate Q as the HA concentration polarization layer built up. Model parameters were based on data from experiments. Effects of parameters on fluid filtration were investigated. Results: The HA osmotic pressure at the synovial surface was found to approach the intra‐articular pressure, P , during fluid infusion. The model simulated the experimentally observed decay in Q with the time at constant P , and predicted nonlinear P ‐ Q relations in good agreement with experimental results over a range of bulk HA concentrations, from pathological (0.2 g L −1 ) to physiological (4.0 g L −1 ). It gave quantitative insights into the development of the osmotic pressure and the significance of the HA reflection coefficient. Conclusions: The osmotic pressure of a HA concentration polarization layer on the synovial surface leads to outflow buffering. This provides the mechanism by which the vital lubricating synovial fluid is retained in a joint cavity under pressure.