Tribological evaluation of a novel hybrid for repair of articular cartilage defects

The friction and wear properties of silica/poly(tetrahydrofuran)/poly(ε-caprolactone) (SiO2/PTHF/PCL-diCOOH) hybrid materials that are proposed as cartilage tissue engineering materials were investigated against living articular cartilage. A testing rig was designed to allow testing against fresh bovine cartilage. The friction force and wear were compared for five compositions of the hybrid biomaterial articulating against freshly harvested bovine cartilage in diluted bovine calf serum. Under a non-migrating contact, the friction force increased and hence shear force applied to the opposing articular cartilage also increased, resulting in minor damage to the cartilage surface. This worse case testing scenario was used to discriminate between material formulations and revealed the increase in friction and damaged area was lowest for the hybrid containing the most silica. Further friction and wear tests on one hybrid formulation with an elastic modulus closest to that of cartilage were then conducted in a custom incubator system. This demonstrated that over a five day period the friction force, cell viability and glucosaminoglycan (GAG) release into the lubricant were similar between a cartilage-cartilage interface and the hybrid-cartilage interface, supporting the use of these materials for cartilage repair. These results demonstrate how tribology testing can play a part in the development of new materials for chondral tissue engineering

Enzyme degradable star polymethacrylate/silica hybrid inks for 3D printing of tissue scaffolds

There is unmet clinical need for scaffolds that can share load with the host tissue while biodegrading under the action of enzymes present at the site of implantation. The aim here was to create the first enzyme cleavable inorganic–organic hybrid “inks” that can be 3D printed as scaffolds for bone regeneration. Inorganic–organic hybrids are co-networks of inorganic and organic components. Although previous hybrids performed well under cyclic loads, there was little control over their degradation. Here we synthesised new hybrids able to degrade in response to endogenous tissue specific metallo proteinases (collagenases) that are involved in natural remodeling of bone. Three well-defined star polymers, of the monomer 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) and of methyl methacrylate (MMA), of different architectures were prepared by RAFT polymerisation. The linear arms were connected together at an enzyme degradable core using a collagenase cleavable peptide sequence (GLY-PRO-LEU-GLY-PRO-LYS) modified with dimethacryloyl groups as a crosslinker for RAFT polymerisation. The effect of polymer architecture, i.e. the position of the TMSPMA groups on the polymers, on bonding between networks, mechanical properties, biodegradation rate and 3D printability, via direct ink writing, was investigated for the first time and was proven to be critical for all three properties. Specifically, hybrids made with star polymers with the TMSPMA close to the core exhibited the best mechanical properties, improved printability and a higher degradation rate

Surgical treatment for acromioclavicular joint osteoarthritis: patient selection, surgical options, complications, and outcome

Osteoarthritis is one of the most common causes of pain originating from the acromioclavicular (AC) joint. An awareness of appropriate diagnostic techniques is necessary in order to localize clinical symptoms to the AC joint. Initial treatments for AC joint osteoarthritis, which include non-steroidal anti-inflammatory drugs (NSAIDS) and corticosteroids, are recommended prior to surgical interventions. Distal clavicle excision, the main surgical treatment option, can be performed by various surgical approaches, such as open procedures, direct arthroscopic, and indirect arthroscopic techniques. When choosing the best surgical option, factors such as avoidance of AC ligament damage, clavicular instability, and post-operative pain must be considered. This article examines patient selection, complications, and outcomes of surgical treatment options for AC joint osteoarthritis

Bioactive glass-derived trabecular coating: a smart solution for enhancing osteointegration of prosthetic elements

In this work, the use of foam-like glass-ceramic scaffolds as trabecular coatings on ceramic prosthetic devices to enhance implant osteointegration is proposed. The feasibility of this innovative device was explored in a simplified, flat geometry: glass-ceramic scaffolds, prepared by polymeric sponge replication and mimicking the trabecular architecture of cancellous bone, were joined to alumina square substrates by a dense glass coating (interlayer). The role played by different formulations of starting glasses was examined, with particular care to the effect on the mechanical properties and bioactivity of the final coating. Microindentations at the coating/substrate interface and tensile tests were performed to evaluate the bonding strength between the sample's components. In vitro bioactive behaviour was assessed by soaking in simulated body fluid and evaluating the apatite formation on the surface and inside the pores of the trabecular coating. The concepts disclosed in the present study can have a significant impact in the field of implantable devices, suggesting a valuable alternative to traditional, often invasive bone-prosthesis fixatio