Abstract
Abstract
Objectives
Current use of hard biomaterials such as cobalt-chrome alloys or ceramics to articulate against the relatively soft, compliant native cartilage surface reduces the joint contact area by up to two thirds. This gives rise to high and abnormal loading conditions which promotes degradation and erosion of the mating cartilage leading to pain, stiffness, and loss of function. Biomimetic soft lubrication strategies have been developed by grafting hydrophilic polymers onto substrates to form a gel-type surface. Surface grafted gels mimic the natural mechanisms of friction dissipation in synovial joints, showing a promising potential for use in hemiarthroplasty. This project aims to develop implant surfaces with properties tailored to match articular cartilage to retain and promote natural joint function ahead of total joint replacement.
Methods
Four different types of monomers were grafted in a one-step photopolymerisation procedure onto polished PEEK substrates. The functionalised surfaces were investigated using surface wettability, FTIR, and simplified 2D-tribometry tests against glass and animal cartilage specimens to assess their lubricity and mechanical properties for hemiarthroplasty articulations.
Results
Polymer functionalised surfaces under different grafting conditions were assessed for their wettability, graft density and quality. A reduction in water contact angle from 90° to < 20° was seen for functionalised highly hydrophilic PEEK surfaces. Similarly a reduction in the coefficient of friction (and subsequently shear stresses acting on cartilage) of 95% to ∼ 10−2 was seen for functionalised PEEK surfaces slid against glass and cartilage in PBS.
Conclusions
Development of this technology has the potential to vastly improve the performance of hemiarthroplasty. Providing earlier and targeted interventions for degenerative joint disease whilst preserving the function of the remaining healthy cartilage. Future work will concern using these promising hydrated functionalised surface architectures as focal cartilage deflects plugs along with long-term performance and suitability for implantation assessments using joint simulator testing.
