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Updated: Mar 2, 2026

A Friction Testing-Bioreactor Device for Study of Synovial Joint Biomechanics, Mechanobiology, and Physical Regulation
Published on: June 2, 2022
Repulsive surfaces and lamellar lubrication of synovial joints
Zenon Pawlak1, Kehinde Q Yusuf2, Raghuvir Pai3
1Tribochemistry Consulting, Salt Lake City, UT 84117, USA; University of Economy, Biotribology Laboratory, Garbary 2, 85-229 Bydgoszcz, Poland; Kujawy University, Plac Wolności 1, 87-800 Włocławek, Poland.
Abstract:
Surface-active phospholipid (SAPL) secreted in the synovial joint plays an important role in cartilage integrity. In healthy joints, phospholipid multibilayers coat the cartilage surface, providing boundary lamellar-repulsive hydration lubrication. Current mechanism for lubrication of synovial joints, as well as the physical and chemical nature of the cartilage surface is discussed. Friction between phospholipid (PL) bilayers attached to cartilage surfaces is considered including a discussion on the recent observation of an extreme friction reduction as a consequence of a less charged hydrophilic cartilage surface. It is proposed that the highly efficient lubrication occurring in natural joints arises from the presence of negatively charged cartilage surfaces. The lamellar-repulsive mechanisms for the reduction of friction is supported by phospholipid lamellar phases and charged macromolecules residing between contacting cartilage surfaces at pH ∼7.4.
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