Cartilage wear simulation models for surface and spacer hemiarthroplasty and tissue engineering

Understanding the wear of the biomaterial/cartilage interface is vital in the
development of more satisfactory materials for use in the clinical repair of
worn or damaged synovial joints. The aims of this study were to investigate a
wide range of biphasic hydrogels as potential chondroplasty materials and to
further the understanding of natural joint tribology. The mechanical
properties of each potential chondroplasty material were quantified and their
tribological performance investigated by means of a series of simple
geometry friction and wear studies in Ringer's solution and a proteincontaining
lubricant. Also uni- and multi-directional continuous sliding tests
in a protein-containing lubricant were conducted under various loading
conditions to evaluate the friction and degradation of each material and that
of the opposing articular cartilage surface. A number of potential
chondroplasty materials were also evaluated as defect repair materials when
implanted using a proposed clinical method. Selected biphasic hydrogel
materials showed a marked reduction in dynamic friction, degradation and
articular cartilage pin damage when compared with single-phase materials.
Following continuous wear studies, alterations in opposing cartilage surface
topography were found to be associated with increased levels of dynamic friction.
The protocols devised in this study are the first to yield objective and
quantifiable data demonstrating a reduction in friction and opposing cartilage
surface degradation following the implantation of certain biphasic hydrogel
defect repair materials. They also demonstrate the potential of biphasic
hydrogels to act as superior chondroplasty materials compared with currently
available materials. Future work will focus on the optimisation of biphasic
hydrogel properties, including the long-term durability and immunogenicity
of each material following implantation, in order that materials will more
closely mimic the tribology of natural articular cartilage.