Developing porosity of poly(propylene glycol-co-fumaric acid) bone graft substitutes and the effect on osteointegration: A preliminary histology study in rats

Abstract

Bioresorbable bone graft substitutes could eliminate disadvantages associated with the use of autografts, allografts and other synthetic materials. We investigated a bioresorbable bone graft substitute made from the unsaturated polyester poly(propylene fumarate) which is crosslinked in the presence of soluble and insoluble calcium filler salts. This compact bone graft substitute material develops porosity in vivo by leaching of the soluble filler salts. In attempt to develop materials whose in vivo porosity can be designed such that implant degradation would occur at a rate that remains supportive of the overall structural integrity of the repairing defect site, we studied the early tissue response upon implantation in a bony defect. Three grout formulations of varying solubilities using slightly soluble hydroxyapatite (HA) and soluble calcium acetate (CA) were evaluated in 3 mm holes made in the anteromedial tibial metaphysis of 200 g Sprague Dawley rats (n = 16 per formulation for a total of 48 animals). Grout formulations cured in situ. Animals from each formulation were sacrificed in groups of 8 at 4 days and 3 weeks postoperatively. Histologic analysis of the healing process revealed improved in vivo osteointegration of bone graft substitutes when a higher loading of calcium acetate was employed. All formulations maintained implant integrity and did not provoke sustained inflammatory responses. This study suggested that the presence of a soluble salt permits in vivo development of porosity of a poly(propylene fumarate) based bone graft substitute material.

Biomimetic Modification of Porous TiNbZr Alloy Scaffold for Bone Tissue Engineering

“…Similarly, bone ingrowth was shown to be deeper and greater in higher porous polymer scaffolds. 38 However, the elastic modulus and compressive strength of a scaffold material decrease with the increase of porosity. For a typical porous material, the relationships between the plateau stress, elastic modulus, and the relative density are given by …”

Introductory Chapter: Multi-Aspect Bibliographic Analysis of the Synergy of Technical, Biological and Medical Sciences Concerning Materials and Technologies Used for Medical and Dental Implantable Devices

“…Bone regeneration in vivo porous implants consists of recruitment and penetration of cells from the surrounding bone tissue and vascularisation [212]. Higher porosity may facilitate such processes and enable bone growth [213,214]. The influence of the pore size on the growth of cells, e.g., bone cells, is, however, still controversial [195,215].…”

Use of Polyurethane Foam in Orthopaedic Biomechanical Experimentation and Simulation

“…Bone grafting is a reconstructive orthopaedic procedure in which a bone substitute is used to fuse broken bones and to repair skeletal defects (Arrington et al, 1996, Lewandrowski et al, 2000. Bone grafting is performed worldwide around 2.2 million times per year, with approximately 450 000 procedures in the United States alone (Russell and Block, 2000).…”