Injecting hyaluronan in the thoracolumbar fascia: A model study.

Hyaluronan (HA) has been recently identified as a key component of the densification of thoracolumbar fascia (TLF), a potential contributor to non-specific lower back pain (LBP) currently treated with manual therapy and systemic or local delivery of anti-inflammatory drugs. The aim of this study was to establish a novel animal model suitable for studying ultrasound-guided intrafascial injection prepared from HA with low and high Mw. Effects of these preparations on the profibrotic switch and mechanical properties of TLF were measured by qPCR and rheology, respectively, while their lubricating properties were evaluated by tribology.

A composite device for viscosupplementation treatment resistant to degradation by reactive oxygen species and hyaluronidase.

Osteoarthritis (OA) is one of the most common musculoskeletal disorders in the world. OA is often associated with the loss of viscoelastic and tribological properties of synovial fluid (SF) due to degradation of hyaluronic acid (HA) by reactive oxygen species (ROS) and hyaluronidases. Viscosupplementation is one of the ways how to effectively restore SF functions.

Tribological behaviour of 3D printed materials for small joint implants: A pilot study.

Additive manufacturing is a progressive method in endoprosthetics enabling customisation of implants. However, the challenge is to design articulating surfaces that are wear resistant in a long term. To tackle this challenge, it is necessary to understand the interaction between the surfaces and the lubricant synovial fluid as well as the mechanism of lubrication film formation.

Insight into the Lubrication and Adhesion Properties of Hyaluronan for Ocular Drug Delivery.

Hyaluronan (HA) is widely used for eye drops as lubricant to counteract dry eye disease. High and low molecular weight HA are currently used in ophthalmology. However, a large portion of the current literature on friction and lubrication addresses articular (joint) cartilage.

Analysis of Chemisorbed Tribo-Film for Ceramic-on-Ceramic Hip Joint Prostheses by Raman Spectroscopy.

To understand the possible lubricant mechanism in ceramic-on-ceramic hip joint prostheses, biochemical reactions of the synovial fluid and the corresponding frictional coefficients were studied. The experiments were performed in a hip joint simulator using the ball-on-cup configuration with balls and cups made from two types of ceramics, BIOLOXforte and BIOLOXdelta. Different lubricants, namely albumin, -globulin, hyaluronic acid and three model synovial fluids, were studied in the experiments and Raman spectroscopy was used to analyze the biochemical responses of these lubricants at the interface.

On the Dependence of Rheology of Hyaluronic Acid Solutions and Frictional Behavior of Articular Cartilage.

Hyaluronic acid (HA) injections represent one of the most common methods for the treatment of osteoarthritis. However, the clinical results of this method are unambiguous mainly because the mechanism of action has not been clearly clarified yet. Viscosupplementation consists, inter alia, of the improvement of synovial fluid rheological properties by injected solution.

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

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.

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

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.

UHMWPE acetabular cup creep deformation during the run-in phase of THA's life cycle.

Ultra-high molecular polyethylene (UHMWPE) is one of the most used materials of the acetabular liners in total tip arthroplasty (THA). Polyethylene has good tribological properties and biocompatibility. However, the lifetime of polyethylene implants is limited by wear related complications.

The Effect of Kinematic Conditions and Synovial Fluid Composition on the Frictional Behaviour of Materials for Artificial Joints.

The paper introduces an experimental investigation of frictional behaviour of materials used for joint replacements. The measurements were performed using a ball-on-disc tribometer, while four material combinations were tested; metal-on-metal, ceramic-on-ceramic, metal-on-polyethylene, and ceramic-on-polyethylene, respectively. The contact was lubricated by pure saline and various protein solutions.

Enhanced lubricant film formation through micro-dimpled hard-on-hard artificial hip joint: An in-situ observation of dimple shape effects.

This study evaluates the impact of dimple shapes on lubricant film formation in artificial hip joints. Micro-dimples with 20-50 µm lateral size and 1 ± 0.2 µm depths were fabricated on CrCoMo hip joint femoral heads using a picosecond laser.

Mechanical wear and oxidative degradation analysis of retrieved ultra high molecular weight polyethylene acetabular cups.

The number of revision joint replacements has been increasing substantially over the last few years. Understanding their failure mechanism is extremely important for improving the design and material selection of current implants. This study includes ten retrieved and four new mildly cross-linked ultra-high molecular weight polyethylene (UHMWPE) acetabular liners.

The impact of surface and geometry on coefficient of friction of artificial hip joints.

Coefficient of friction (COF) tests were conducted on 28-mm and 36-mm-diameter hip joint prostheses for four different material combinations, with or without the presence of Ultra High Molecular Weight Polyethylene (UHMWPE) particles using a novel pendulum hip simulator. The effects of three micro dimpled arrays on femoral head against a polyethylene and a metallic cup were also investigated. Clearance played a vital role in the COF of ceramic on polyethylene and ceramic on ceramic artificial hip joints.

Characteristics of synovial fluid required for optimization of lubrication fluid for biotribological experiments.

Wear testing of total joint replacement (TJR) is mandatory in preclinical testing before implantation of TJR into the human body. Testing is governed by current international standards that recommend bovine serum (BS) as a lubricating fluid to replace synovial fluid (SF). Recently, the use of BS has been criticized because of differences in content, fluid characteristics, and nonhuman origin.

The effect of lubricant constituents on lubrication mechanisms in hip joint replacements.

The aim of the present paper is to provide a novel experimental approach enabling to assess the thickness of lubricant film within hip prostheses in meaning of the contribution of particular proteins. Thin film colorimetric interferometry was combined with fluorescent microscopy finding that a combination of optical methods can help to better understand the interfacial lubrication processes in hip replacements. The contact of metal femoral head against a glass disc was investigated under various operating conditions.

Towards near-permanent CoCrMo prosthesis surface by combining micro-texturing and low temperature plasma carburising.

An advanced surface engineering process combining micro-texture with a plasma carburising process was produced on CoCrMo femoral head, and their tribological properties were evaluated by the cutting-edge pendulum hip joint simulator coupled with thin film colorimetric interferometry. FESEM and GDOES showed that precipitation-free C S-phase with a uniform case depth of 10μm was formed across the micro-textures after duplex treatment. Hip simulator tests showed that the friction coefficient was reduced by 20% for micro-metre sized texture, and the long-term tribological property of microtexture was enhanced by the C-supersaturated crystalline microstructure formed on the surface of duplex treated CoCrMo, thereby enhancing biotribological durability significantly.

A novel tribological study on DLC-coated micro-dimpled orthopedics implant interface.

This study investigates a tribological performance of diamond like carbon (DLC) coated micro dimpled prosthesis heads against ceramic cups in a novel pendulum hip joint simulator. The simulator enables determining friction coefficient and viscous effects of a concave shaped specimen interface (conformal contact). Two types of DLC such as hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (Ta-C) and one set of micro dimple (diameter of 300µm, depth of 70µm, and pitch of 900µm) were fabricated on metallic prosthesis heads.

Fabrication and characterization of DLC coated microdimples on hip prosthesis heads.

Diamond like carbon (DLC) is applied as a thin film onto substrates to obtain desired surface properties such as increased hardness and corrosion resistance, and decreased friction and wear rate. Microdimple is an advanced surface modification technique enhancing the tribological performance. In this study, DLC coated microdimples were fabricated on hip prosthesis heads and their mechanical, material and surface properties were characterized.

In situ measurements of thin films in bovine serum lubricated contacts using optical interferometry.

The aim of this study is to consider the relevance of in situ measurements of bovine serum film thickness in the optical test device that could be related to the function of the artificial hip joint. It is mainly focussed on the effect of the hydrophobicity or hydrophilicity of the transparent surface and the effect of its geometry. Film thickness measurements were performed using ball-on-disc and lens-on-disc configurations of optical test device as a function of time.

Stress and strain analysis of the hip joint using FEM.

Many disorders of the hip can be treated with a suitable osteotomy based on the improvement of mechanical conditions in the hip joint. These operations, such as osteotomies are very complex. The surface replacement has also been developed as an alternative to a total hip replacement for young and more active people.