Highly lubricious SPMK-g-PEEK implant surfaces to facilitate rehydration of articular cartilage
Description
Data Corresponding to 'Highly lubricious SPMK-g-PEEK implant surfaces to facilitate rehydration of articular cartilage' Elkington 2023 To enable long lasting osteochondral defect repairs which preserve the native function of synovial joint counter-face, it is essential to develop biomimetic surfaces which are optimised to support healthy cartilage function by providing a hydrated, low friction and compliant sliding interface. PEEK surfaces were functionalised with biocompatible polyelectrolyte 3-sulfopropyl methacrylate potassium salt (SPMK) via UV photo-polymerisation. Fourier Transformed Infrared Spectroscopy, Focused Ion Beam Scanning Electron Microscopy and Water Contact Angle measurements were used to profile the sub micron (∼ 350 nm) thick surface coating containing highly hydrophilic sulfonic acid groups. A Bruker UMT TriboLab was employed to facilitate bovine cartilage sliding tests with in-situ real-time strain measurement against untreated PEEK, SPMK functionalised PEEK (SPMK-g-PEEK) and Cobalt Chrome Molybdenum alloy as a representative hip implant material. Simultaneous friction and strain measurements over 2.5 hours of sliding at physiological loads of 0.75 MPa demonstrates SPMK-g-PEEK sustains low friction (µ < 0.024) and minimises equilibrium strain throughout testing, greatly reducing the forces exerted on the cartilage interface. Analysis of the cartilage surface following mechanical tests also demonstrate no discernible damage to the solid collagen cartilage matrix for SPMK functionalised surfaces. Biphasic cartilage models applied to the temporal strain response during sliding provides a novel indication that SPMK surfaces can support a greater amount of fluid load support in cartilage, protecting the health and mechanical viability of the solid collagen matrix. SPMK-g-PEEK surfaces provide an enhanced bearing surface for interfacing with healthy cartilage without adversely loading the contact area. Soft biomimetic polymer surface functionalisation of orthopaedic implant surfaces are a promising approach for minimally invasive synovial joint repair with a biomimetic interface optimised for sliding against cartilage. These hydrophilic surface coatings offer enabling technology for the next generation of bioinspired focal cartilage repair and hemiarthroplasty implant surfaces. Keywords: Polymer Brushes, Cartilage, Cartilage Repair, Orthopaedic Engineering, BioTribology
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All data handling performed with Python, all interested persons are invited to get in touch with Rob Elkington for clarity on data analysis and copies of relevant python scripts.