The Effect of Synovial Fluid Composition, Speed and Load on Frictional Behaviour of Articular Cartilage

Abstract

Articular cartilage ensures smooth motion of natural synovial joints operating at very low friction. However, the number of patients suffering from joint diseases, usually associated with cartilage degradation, continuously increases. Therefore, an understanding of cartilage tribological behaviour is of great interest in order to minimize its degradation, preserving the reliable function of the joints. The aim of the present study is to provide a comprehensive comparison of frictional behaviour of articular cartilage, focusing on the effect of synovial fluid composition (i), speed (ii), and load (iii). The experiments were realized using a pin-on-plate tribometer with reciprocating motion. The articular cartilage pin was loaded against smooth glass plate while the tests consisted of loading and unloading phases in order to enable cartilage rehydration. Various model fluids containing albumin, γ-globulin, hyaluronic acid, and phospholipids were prepared in two different concentrations simulating physiologic and osteoarthritic synovial fluid. Two different speeds, 5 mm/s and 10 mm/s were applied, and the tests were carried out under 5 N and 10 N. It was found that protein-based solutions exhibit almost no difference in friction coefficient, independently of the concentration of the constituents. However, the behaviour is considerably changed when adding hyaluronic acid and phospholipids. Especially when interacting with γ-globulin, friction coefficient decreased substantially. In general, an important role of the interaction of fluid constituents was observed. On the other hand, a limited effect of speed was detected for most of the model fluids. Finally, it was shown that elevated load leads to lower friction, which corresponds well with previous observations. Further study should concentrate on specific explored phenomena focusing on the detailed statistical evaluation.

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

“…Though the samples were removed from different animals, the values and trends of CoF were comparable; nevertheless, the deviation of CoF depended on the combination of friction samples, testing conditions, etc. A rise in CoF trends, which was shown in this study, has been known from other publications [38,[46][47][48][49][50][51][52][53][54][55][56][57][58][59][60], and the values of CoF were comparable depending on the processing conditions, configuration of specimens, and lubricants. A comparison of particle count trends showed that the ϒ-globulin protein clusters were wiped off faster from the contact than the albumin; thus, the lubrication film was formed especially by albumin clusters.…”

“…The samples were removed by a hollow punch with an internal diameter of 9.7 mm and stored in phosphate-buffered saline (PBS), deeply frozen (−20 • C), and defrosted immediately before the experiments. The same sampling procedure was used in [55,58] and verified in [64,65]. The sampling process is shown in Figure 4.…”

“…The number of "friction" studies is higher because the friction measurement methodology is better developed, and these works indicate well the understanding of the cartilage friction behavior. The behavior of cartilage lubricated by synovial fluid was presented in [51][52][53][54][55] showing that the synovial fluid reports a very low CoF. HA helps to lower CoF [54]; CoF grows with time [51,52,[54][55][56][57][58]; CoF decreases with a rising load [51,57,58]; CoF is influenced by the type of movement depending on the cartilage sampling [52,59]; and the cartilage rehydration has a positive impact on CoF [60].…”

Raman analysis of chemisorbed tribofilm for metal‐on‐polyethylene hip joint prostheses

“…These model fluids were prepared with concentrations of components at real physiologic values, as evaluated by Galandakova et al [25]. In particular, the three types of model fluids are the mimic of SF of healthy or physiologic joint (SF1), SF of total joint replacement (SF2) and SF within a joint with osteoarthritis (SF3) [25,29]. In the model fluids, the concentrations of albumin, γ-globulin, HA and phospholipids were maintained within the range observed in human joints, as described in Table 1.…”

“…Although the molecular weight of HA has a vital impact on its rheological properties, the HA molecular weight and its coefficient of friction had no mutual dependency [44]. Also, only a limited effect on friction was found when protein-based lubricants were applied varying the fluid constituent concentration in the range corresponding to physiologic and osteoarthritic SF [29]. A dependence between the coefficient of friction for model fluids, proteins and HA with chemical changes of Co-Cr-Mo could not be identified.…”