Effect of increased strut porosity of calcium phosphate bone graft substitute biomaterials on osteoinduction

Abstract

The effect of increasing strut porosity on the osteoinductivity of porous calcium phosphate (CaP) and silicate-substituted calcium phosphate (SiCaP) bone substitute materials was investigated in an ovine ectopic model. One to two millimeter-sized granules or block implants with strut porosities of 10, 20, or 30% were inserted into the left and right paraspinalis muscle. At 12 weeks, histological sections were prepared through the center of each implant and bone contact, bone area and implant area quantified. Backscattered scanning electron microscopy (bSEM) was used to visualize bone within small pores in the struts of the scaffolds. Increased bone formation was measured in the SiCaP with 30% strut porosity (5.482% ± 1.546%) when compared with the nonsilicate CaP with the same morphology (1.160% ± 0.502%, p = 0.02), indicating that silicate substitution may increase osteoinduction. Greater bone formation was seen in scaffolds with increased strut porosity. No bone growth was found in any of the SiCaP scaffold with 10% porosity. There was no significant difference between block and granule specimens. Scanning electron microscopy and EDX in combination with histology demonstrated bone formation within pores <5 μm in size. The use of silicate-substituted CaP material with increased strut porosity may further augment repair and regeneration in bony sites.

Effect of grain size and microporosity on the in vivo behaviour of β-tricalcium phosphate scaffolds

“…However, Campion et al (Campion et al, 2011) (twofold change of microporosity) and Coathup et al (Coathup et al, 2012) (three-fold change of microporosity) observed highly significant effects. Moreover, even though the number of experimental repeats (n = 6) was below the number generally recommended in standardised animal tests (n = 8), the experiments were performed according to a factorial design of experiment.…”

“…Campion et al (Campion et al, 2011) studied the effect of a twofold change of the strut (micro)porosity (23 to 46 %) on the in vivo performance of a silicon-substituted hydroxyapatite. For Coathup et al (Coathup et al, 2012), the range was slightly larger (from 10 to 30 %). As a last example, Klein et al (Klein et al, 1983;Klein et al, 1985;Klein et al, 1986) varied the microporosity over a wider range (in one case from 2 to 60 %), but other architectural parameters were also affected such as the total porosity.…”

“…Lan Levengood et al (Lan Levengood et al, 2010) stated that "the exploitation of microporosity to achieve multiscale osteointegration offers a new paradigm for scaffold design". More recently, the presence of micropores was associated with the osteoinductive potential of calcium phosphate (CaP) ceramics (Yuan et al, 2010;Chan et al, 2012;Coathup et al, 2012), and a change in cell and bone ingrowth (Lan Levengood et al, 2010;Polak et al, 2013). Regarding grain size, grain boundaries were found to be attacked during resorption, leading to particle release ( Van der Meulen and Koerten, 1994).…”

“…These include porosity (Klein et al, 1985;Metsger et al, 1993), pore size (Klawitter and Hulbert, 1971;van Blitterswijk et al, 1986;Eggli et al, 1988;Daculsi and Passuti, 1990;Schliephake et al, 1991;Metsger et al, 1993;Ayers et al, 1999;Itala et al, 2001;von Doernberg et al, 2006;Chan et al, 2012), interconnection pore size (Lu et al, 1999;Flautre et al, 2001) or granule size (Malard et al, 1999;Murakami et al, 2010). Microscopic features such as micropores or crystal grain size have also been the subject of investigations (Klein et al, 1983;Klein et al, 1984;Klein et al, 1985;Klein et al, 1986;De Groot, 1988;De Groot et al, 1988;Van der Meulen and Koerten, 1994;Gauthier et al, 1999;Lan Levengood et al, 2010;Wei et al, 2010;Yuan et al, 2010;Campion et al, 2011;Chan et al, 2012;Coathup et al, 2012) (Table 1). For example, Wei et al (Wei et al, 2010) implanted magnesium-calcium phosphate macroporous scaffolds with Table 1.…”

The biopolymer sugarcane as filling material of critical defects in rats

“…In critical bone defects on calvaria of Wistar rats, SCB gel preparations associated with bone morphogenetic protein (BMP) showed to be a suitable scaffold for the BMP, presumably facilitating the controlled release of BMP during bone repair 11 . Although some studies proposed SCB as a promising material for grafting and other medical procedures, none of those researches aimed bone grafting with granulated SCB to this date [12][13][14][15][16][17] . Therefore, this paper focused on the effects of particulate (granule-shaped) SCB on bone repair relating it to its biocompatibility and bone neoformation.…”