Biotribology of Synovial Cartilage: A New Method for Visualization of Lubricating Film and Simultaneous Measurement of the Friction Coefficient

Abstract

A healthy natural synovial joint is very important for painless active movement of the natural musculoskeletal system. The right functioning of natural synovial joints ensures well lubricated contact surfaces with a very low friction coefficient and wear of cartilage tissue. The present paper deals with a new method for visualization of lubricating film with simultaneous measurements of the friction coefficient. This can contribute to better understanding of lubricating film formation in a natural synovial joint. A newly developed device, a reciprocating tribometer, is used to allow for simultaneous measurement of friction forces with contact visualization by fluorescence microscopy. The software allowing for snaps processing and subsequent evaluation of fluorescence records is developed. The evaluation software and the follow-up evaluation procedure are also described. The experiments with cartilage samples and model synovial fluid are carried out, and the new software is applied to provide their evaluation. The primary results explaining a connection between lubrication and friction are presented. The results show a more significant impact of albumin proteins on the lubrication process, whereas its clusters create a more stable lubrication layer. A decreasing trend of protein cluster count, which corresponds to a decrease in the thickness of the lubrication film, is found in all experiments. The results highlight a deeper connection between the cartilage friction and the lubrication film formation, which allows for better understanding of the cartilage lubrication mechanism.

Characterization of Synovial Fluid Components: Albumin-Chondroitin Sulfate Interactions Seen through Molecular Dynamics

“…The strength of the interactions depends on, e.g., the amount of ions provided in the system, and affects the rheological and tribological properties of the cartilage [ 12 ]. HSA:HA-based complexes are good lubricants, and they considerably lower the friction coefficient [ 42 , 43 ]. New thin-film materials based on albumin and HA have been proposed to be used in biomedicine and cosmetics due to their adhesive properties [ 44 ].…”

A review of advances in tribology in 2020–2021

“…Delamination of the articular surface, starting in the middle zone, was found in a reciprocal sliding of tibial cartilage strips against glass or cartilage, with immature cartilage showing significant less cycles [628]. A direct visualization of lubricating film and simultaneous measurement of the friction coefficient were developed in a novel setup [629]. Most of these studies were conducted experimentally, however analytical and computational approaches were also increasingly developed.…”

Influence of Nanoparticle Chemical Composition on <i>In Situ</i> Hydrogel Friction

“…Given the vast range of possibilities for nanoparticles, additional reviews have highlighted numerous studies including organic and inorganic based nanoparticles effective in direct therapeutics and as delivery systems [7][8][9] What is lacking from many of these studies, however, is the consideration of joint movement and the impact of nanoparticle additives on sliding. An extensive collection of literature examines joint friction [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] and mimetic materials such as hydrogels [26][27][28][29][30][31][32] (note the literature cited here is not a comprehensive list), yet few connect nanoparticles in synovial joints to sliding, and tend to focus on polymeric-based nanoparticles. In simulations by Jamalabadi [13] hollow silica nanoparticles with core/shell charged polymer brushes were evaluated in a modeled knee, finding that an increase in nanoparticle concentration decreased the maximum pressure on the squeeze film.…”