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Session: Joints
Session starts: Friday 25 January, 13:00
Presentation starts: 14:00
Room: Lecture room 535

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Rienk Schuiringa (Orthopaedic Biomechanics, Biomedical Engineering, Eindhoven University of Technology )
René van Donkelaar ()
Keita Ito ()

Abstract:
Cartilage defects occur frequently and can progress into osteoarthritis, which is painful and progressive, leading to serious functional limitations. Current treatments for defects are limited to specific age groups, lesion sites or sizes. The proposed solution is a biomimetic implant where artificial cartilage involves a HydroSpacer, existing of a knitted spacer fabric incorporated with a hydrogel that has strong swelling potential. The mechanical load-bearing function of the artificial cartilage originates from the restriction of the swelling by the spacer fabric fibres. The goal of this study is to develop an implant construct, which possess the mechanical properties of native cartilage. The swelling potential of the hydrogel is believed to have a strong influence on the mechanical properties of the HydroSpacer. Preliminary research involved HydroSpacers of poly 2-hydroxyethyl methacrylate (pHEMA) hydrogel synthesized with three different compositions and a poly lactic acid (PLA) spacer fabric. The hydrogel incorporated in the spacer fabric was polymerized using UV light and placed in PBS overnight to equilibrate in swollen state. The HydroSpacers and native porcine tibial plateau cartilage were mechanically tested using a Zwick tensile tester. Creep tests were performed using a 2 mm spherical-tip indenter. Loads of 10N, 25N and 0N were subsequently applied for 600 seconds, during which the indentation depth was monitored. Results demonstrate that the HydroSpacer stiffness is in the correct range (Table 1), while the time-dependent response of the HydroSpacer is quicker than that of cartilage. Load HydroSpacer (n=1) Cartilage (n=1) Maximum strain 10N 45%-55% 65% Maximum strain 25N 65%-83% 87% Residual strain 10N 9% 37% Residual strain 25N 12%-15% 51% Concluding, the first preliminary results are promising. Both the time-dependent and equilibrium responses of the HydroSpacer are within reasonable range from those of cartilage. This makes it likely that the properties of the construct can be sufficiently optimized by tuning the properties of either the hydrogel or the spacer fabric properties. Future developments will further characterize the constructs under a variety of mechanical conditions, optimize the construct to mimic the properties of cartilage, and use cell-seeded chondroitin sulfate methacrylate/hyaluronic acid methacrylate (CSMA/HAMA) hydrogels.