title: Comparison of friction and wear of articular cartilage on different length scales.
abstract: The exceptional tribological properties of articular cartilage are still far from being fully understood. Articular cartilage is able to withstand high loads and provide exceptionally low friction. Although the regeneration abilities of the tissue are very limited, it can last for many decades. These biomechanical properties are realized by an interplay of different lubrication and wear protection mechanisms. The deterioration of cartilage due to aging or injury leads to the development of osteoarthritis. A current treatment strategy focuses on supplementing the intra-articular fluid with a saline solution containing hyaluronic acid. In the work presented here, we investigated how changing the lubricating fluid affects friction and wear of articular cartilage, focusing on the boundary and mixed lubrication as well as interstitial fluid pressurization mechanisms. Different length and time scales were probed by atomic force microscopy, tribology and profilometry. We compared aqueous solutions with different NaCl concentrations to a viscosupplement containing hyaluronic acid (HA). In particular, we found that the presence of ions changes the frictional behavior and the wear resistance. In contrast, hyaluronic acid showed no significant impact on the friction coefficient, but considerably reduced wear. This study confirms the previous notion that friction and wear are not necessarily correlated in articular cartilage tribology and that the main role of HA might be to provide wear protection for the articular surface.
authors: Physics Department and Institute for Medical Engineering, IMETUM, Technische Universität München, Boltzmannstr. 11, 85748 Garching, Germany.
authors: Sandra
authors: S
authors: Kienle
authors: Department for Mechanical Engineering and Institute for Medical Engineering, IMETUM, Technische Universität München, Boltzmannstr. 11, 85748 Garching, Germany.
authors: Kathrin
authors: K
authors: Boettcher
authors: Physics Department and Institute for Medical Engineering, IMETUM, Technische Universität München, Boltzmannstr. 11, 85748 Garching, Germany.
authors: Lorenz
authors: L
authors: Wiegleb
authors: Institute of Physical Chemistry, University of Freiburg, Albertstr. 23a, 79104 Freiburg, Germany.
authors: Joanna
authors: J
authors: Urban
authors: Klinik für Orthopädie und Sportorthopädie, Klinikum Rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675 München, Germany.
authors: Rainer
authors: R
authors: Burgkart
authors: Department for Mechanical Engineering and Institute for Medical Engineering, IMETUM, Technische Universität München, Boltzmannstr. 11, 85748 Garching, Germany.
authors: Oliver
authors: O
authors: Lieleg
authors: Physics Department and Institute for Medical Engineering, IMETUM, Technische Universität München, Boltzmannstr. 11, 85748 Garching, Germany; Institute of Physical Chemistry, University of Freiburg, Albertstr. 23a, 79104 Freiburg, Germany. Electronic address: TH@physchem.uni-freiburg.de.
authors: Thorsten
authors: T
authors: Hugel
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects; D017276:Friction / Q000187:drug effects; D006820:Hyaluronic Acid / Q000494:pharmacology; D018625:Microscopy, Atomic Force; D012756:Sheep; D013582:Synovial Fluid / Q000187:drug effects / Q000378:metabolism
chemical_list: D006820:Hyaluronic Acid
keywords: Atomic force microscopy; Friction; Hyaluronic acid; Lubrication; Tribometer; Wear protection