DOS BULLETIN - Dansk Ortopædisk Selskab
DOS BULLETIN - Dansk Ortopædisk Selskab DOS BULLETIN - Dansk Ortopædisk Selskab
2010-378_DOS nr. 3 2010 29/09/10 10:08 Side 108 Development of a Structurally Graded Polycaprolactone Scaffold for Hyaline Cartilage Repair Bjørn B. Christensen, Casper B. Foldager, Asger Kristiansen, Jens Nygaard, Cody Bünger, Martin Lind Orthopeadic Research Laboratory, Aarhus Sygehus; iNano, Aarhus University; Sports- and Trauma clinic, Aarhus Sygehus Background: This study was at pilot study for an ongoing in vivo study. We needed to determine the optimal dioxane-water ratio and molecular weight, of the structurally graded scaffolds, before moving on the animal experiments. Purpose: Rapid prototyping is a very precise scaffold manufacturing technique where scaffolds can be constructed from MRI or CT scans to fit into the individual tissue defects. The aim of this study is to develop a novel Structurally Graded Poly-Capro-Lactone scaffold using rapid prototyping for cartilage tissue engineering. Methods: A novel SG-PCL scaffold was constructed using rapid prototyping ?(Ø 4 mm, height 2 mm). PCL fibers (MW 50 kDa) with a diameter of 120 m were plotted producing a 3-dimensional web. The scaffold was subsequently submerged into a mixture of dioxane, PCL and water, and lyophilized at -32°C, creating an extremely porous graded structure. By shifting the water-dioxane ratio, 16 batches of scaffolds with different pore sizes were made. Using scanning electron microscopy, two scaffolds were selected, based on porous structure. The two scaffolds were then constructed with a graded structure of 25 and 50 kDa, giving a total of four different scaffolds (#1-4). They were cultured with human chondrocytes and the viability was analyzed using confocal microscopy after 1, 3 and 6 days. The scaffolds were rated based on cell migration, cell shape and distribution of viable cells. Findings: The scaffolds contained macro-, micro-, and nano-pores. A large difference in investigated parameters was observed and Scaffold #3 with a water-dioxane ratio of 0.0415 provided the most viable environment for chondrocytes according to the above-mentioned criteria. This scaffold consisted of PCL fibers of 50 kDa and lyophilized PCL of 25 kDa. Conclusion: We successfully constructed a SG-PCL scaffold that can be used in future in vivo experiments, and has the potential of subsequent functionalization with nanoparticles and growth- and differentiation factors. 108
2010-378_DOS nr. 3 2010 29/09/10 10:08 Side 109 The Wear Effect of Hydrophilic Coatings on Hard Implants Sune Lund Sporring, Jes Bruun Lauritzen, Povl Brøndsted, Kion Norrman Bispebjerg Hospital; DTU-Risø Background: A serious limiting factor in implant lifetime is wear. Many methods, including ceramic, MoM and highly polishable products, contribute to reducing wear, however other surface treatments are also accessible. Lubricating films often contribute very low friction in many non- medical applications, and could therefore possibly reduce the wear in implants. Purpose: During development of an interpositional intraarticular implant device, experimentation was done with introducing a water film covalently bonded directly to the polymeric implant surfaces. This study is concerned with quantifying the coating and its effect in reducing wear. Methods: Poly(vinyl pyrolidone) (PVP) was coated uniformly on a poly(ethylene) implant (as well as simplified discs) in a custom made plasma coating chamber with 3 electrodes employing 0-600V, and using dried vinyl pyrrolidone monomer. Several techniques were used to quantify the PVP coating: TOF-SIMS, XPS, CLSM, Photomicrography, ATR-FTIR and Pin on disc. Findings: Using a Pin on disc investigation, results were obtained quantifying frictional coefficients. The discs were tested at a constant speed of 0,01 m/s and loads corresponding roughly to the normal walking forces in a hip joint at 37°C ± 1° C. 1) The coefficient of friction was in all cases found to be in the range of 0.12 to 0.18. 2) No significant difference can be seen between PVP coated and not- coated discs. This was later verified in a 3D hip joint test rig at Risø. 3) The coating was removed or compressed due to wear (supported by the observation that the surface properties changed from hydrophilic to hydrophobic). 4) The results did not differ when changing track diameter, loads or sampling frequency (1Hz to 10Hz). Conclusion: Adding a thin (
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2010-378_<strong>DOS</strong> nr. 3 2010 29/09/10 10:08 Side 109<br />
The Wear Effect of Hydrophilic Coatings on Hard<br />
Implants<br />
Sune Lund Sporring, Jes Bruun Lauritzen,<br />
Povl Brøndsted, Kion Norrman<br />
Bispebjerg Hospital; DTU-Risø<br />
Background: A serious limiting factor in implant lifetime is wear. Many<br />
methods, including ceramic, MoM and highly polishable products, contribute<br />
to reducing wear, however other surface treatments are also accessible.<br />
Lubricating films often contribute very low friction in many non- medical<br />
applications, and could therefore possibly reduce the wear in implants.<br />
Purpose: During development of an interpositional intraarticular implant<br />
device, experimentation was done with introducing a water film covalently<br />
bonded directly to the polymeric implant surfaces. This study is concerned<br />
with quantifying the coating and its effect in reducing wear.<br />
Methods: Poly(vinyl pyrolidone) (PVP) was coated uniformly on a<br />
poly(ethylene) implant (as well as simplified discs) in a custom made plasma<br />
coating chamber with 3 electrodes employing 0-600V, and using dried<br />
vinyl pyrrolidone monomer. Several techniques were used to quantify the<br />
PVP coating: TOF-SIMS, XPS, CLSM, Photomicrography, ATR-FTIR and<br />
Pin on disc.<br />
Findings: Using a Pin on disc investigation, results were obtained quantifying<br />
frictional coefficients. The discs were tested at a constant speed of 0,01<br />
m/s and loads corresponding roughly to the normal walking forces in a hip<br />
joint at 37°C ± 1° C. 1) The coefficient of friction was in all cases found to<br />
be in the range of 0.12 to 0.18. 2) No significant difference can be seen<br />
between PVP coated and not- coated discs. This was later verified in a 3D<br />
hip joint test rig at Risø. 3) The coating was removed or compressed due to<br />
wear (supported by the observation that the surface properties changed from<br />
hydrophilic to hydrophobic). 4) The results did not differ when changing<br />
track diameter, loads or sampling frequency (1Hz to 10Hz).<br />
Conclusion: Adding a thin (