In Vitro and In Vivo Characterization of Premixed PMMA-CaP Composite Bone Cements

Abstract

Acrylic bone cements, although successful in the field of orthopedics, suffer from a lack of bioactivity, not truly integrating with surrounding bone. Bioactive fixation is expected to enhance cement performance because of the natural interlocking and bonding with bone, which can improve the augmentative potential of the material in applications such as vertebroplasty (VP). In a recent study, two composite cements (PMMA-hydroxyapatite and PMMA-brushite) showed promising results demonstrating no deterioration in rheological and mechanical properties after CaP filler addition. In this study, the dynamic properties of the cements were investigated in vitro and in vivo. The hypothesis was that these composite cements will provide osseointegration around the implanted cement and increase new bone formation, thus decreasing the risk of bone structural failure. The effects of CaP elution were thus analyzed in vitro using these cements. Mass-loss, pore formation, and mechanical changes were tracked after cement immersion in Hank’s salt solution. PMMA-brushite was the only cement with a significant mass loss; however it showed low bulk porosity. Surface porosity increases were observed in both composite cements. Mechanical properties were maintained after cement immersion. In vitro culture studies tested preosteoblast cell viability and differentiation on the cement surface. Cell viability was demonstrated with MTT assay and confirmed on the cement surface. ALP assays showed no inhibition of osteoblast differentiation on the cement surface. In vivo experiments were performed using a rat tibiae model to demonstrate bone ingrowth around the implanted cements. Critical size defects were created and then filled with the cements. The animal studies showed no loss in mechanical strength after implantation and increased bone ingrowth around the composite cements. In summary, the composite cements provided bioactivity without sacrificing mechanical strength.

Biological properties of calcium phosphate biomaterials for bone repair: a review

“…The mechanical testing included monotonic compression and cyclical fatigue tests, in which up to 57% of both PMMA–brushite and PMMA–HA reached sequence 4, demonstrating efficient reinforcement of the fractured vertebrae through stiffness restoration. 161 In their following research, 162 the biological performance of two PMMA–CaP cements were characterized. ALP assays showed no inhibition of osteoblast differentiation on the cement surface.…”

3D printing of bone scaffolds with hybrid biomaterials

“…A biomaterial is defined as any substance or combination of materials, other than drugs or synthetic natural materials, which can be used, for any period, to partially substitute for any tissue, organ or function of the body for the purpose of maintaining or improving the lifespan of an individual [1]. A fundamental requirement of a biomaterial used in clinical medicine is that it is biocompatible, that is, it can coexist with human tissue without causing any undesirable or inappropriate effects [2,3]. Biomaterials can be classified into three main categories: bioinert, intolerant materials that are not capable of inducing any biological interfacial bond between the implant and the host tissue [4,5]; bioactive, capable of interacting with body tissues, forming chemical or biological bonds and favouring the development of processes such as implant fixation, colonisation and tissue regeneration; and bioreabsorbable, materials that are gradually reabsorbed until they disappear entirely and are wholly replaced by new tissue in vivo.…”

Release Characteristics of Enoxaparin Sodium Loaded Polymethylmethacrylate Bone Cement

“…The other is to thoroughly and evenly mix the drug lyophilized powder or ne particles with bone cement powder component. The drug is added in the dough phase so that the drug is wrapped within the bone cement dough [38,39] . The rst method is used in various antibiotic loaded bone cement on the market, such as Palacos ® R+G, CMW ® 1G etc.…”