A novel surface treatment for porous metallic implants that improves the rate of bony ongrowth

Abstract

Rapid implant fixation could prove beneficial in a host of clinical applications from total joint arthroplasty to trauma. We hypothesized that a novel self-assembled monolayer of phosphonate molecules (SAMP) covalently bonded to the oxide surface of titanium alloy would enhance bony integration. Beaded metallic rods were treated with one of three coatings: SAMP, SAMP + RGD peptide, or hydroxyapatite. Rods were inserted retrogradely into both distal femurs of 60 rabbits. Fifteen rabbits were sacrificed at 2, 4, 8, and 16 weeks. At each time, seven specimens for mechanical pull-out testing and three for histomorphometric analysis were available for each coating. At four weeks, both SAMP groups had significantly higher failure loads when compared to hydroxyapatite (p < 0.01). No significant differences were found among groups at other times, though the SAMP-alone group remained stronger at 16 weeks. Histology showed abundant new bone formation around all the three groups, though more enhanced formation was apparent in the two SAMP groups. With this novel treatment, with or without RGD, the failure load of implants doubled in half the time as compared with hydroxyapatite. Where early implant fixation is important, the SAMP treatment provides a simple, cost-effective enhancement to bony integration of orthopaedic implants.

Orthopedic bioactive implants: Hydrogel enrichment of macroporous titanium for the delivery of mesenchymal stem cells and strontium

“…With this aim, cementless implant technology has evolved with the introduction of porous metallic materials to maximize bone ingrowth and bone-to-implant contact. [4][5][6][7] Among the different types of porous titanium, Trabecular Titanium TM (TT) is currently clinically used in acetabular cups and to fill cavitary and segmental bone defects. This macroporous titanium is characterized by multiple layers of hexagonal pores with a 640 lm diameter, 8 macroporosity that facilitates cell migration and bone deposition.…”

Vascular endothelial growth factor attachment to hydroxyapatite via self-assembled monolayers promotes angiogenic activity of endothelial cells

“…SAMs have been shown to be biocompatible [42][43][44][45], and the use of growth factors to promote angiogenesis has been addressed thoroughly in recent literature [15,[46][47][48]. Surface wettability and SAM functional groups have been shown to affect HUVEC and HeLa cell attachment, with preference towards moderate contact angles (40-60°) and methyl and hydroxyl groups [49].…”

Bilayers coating on titanium surface: The impact on the hydroxyapatite initiation

“…Increasing HAp growth rate will therefore improve the osteointegration of the implant. The main factors influencing osteoinduction are the chemical composition [27] and the morphology of the surface. Previous studies indicate that COOH, PO 4 H 2 , SO 3 H and PO 3 H 2 groups are appropriate groups for calcium phosphate nucleation [5,6,12,13,25,27,28].…”

“…The main factors influencing osteoinduction are the chemical composition [27] and the morphology of the surface. Previous studies indicate that COOH, PO 4 H 2 , SO 3 H and PO 3 H 2 groups are appropriate groups for calcium phosphate nucleation [5,6,12,13,25,27,28]. As organophosphonic groups are known to bind strongly to metal oxides [17,22,26,[29][30][31][32] like aluminium, titanium, tantalum oxides, grafting molecules containing numerous phosphonic groups (Scheme 1) could lead to a strong anchorage of HAp to the oxide surface [17,27].…”