Abstract
Summary
A specialised 3D- printed scaffold, combined with fillers and bioactive molecules, can be designed and characterised to demonstrate the efficacy of synthetic, off-the-shelf and custom fabricated scaffolds for the repair of long bone defects.
Introduction
Using specialised three-dimensional (3-D) printing technology, combined with fillers and bioactive molecules, 3-D scaffolds for bone repair of sizable defects can be manufactured with a level of design customization that other methods lack. Hydroxyapatite (HA)/Beta-Tri-Calcium Phosphate (β -TCP) scaffold components may be created that provide mechanical strength, guide osseo- conduction and integration, and remodel over time. Additionally, research suggests that bone morphogenic protein (BMP) stimulates growth and differentiation of new bone. Therefore, we hypothesise that with the addition of BMP, HA- β -TCP scaffolds will show improved regeneration of bone over critical sized bone defects in an in vivo model.
Patients & Methods
Scaffolds were implanted in six New Zealand White rabbits with a 10mm radial defect for 2 and 8 weeks. The scaffolds, made from 15% HA: 85% β-TCP, were designed using ROBOCAD design software and fabricated using a 3-D printing Robocast machine. Scaffolds were sintered at 1100°C for 4 hours with a final composition of 5% HA: ∼95% β-TCP. Micro-CT, histological analysis, and nanoindentation were conducted to determine the degree of new bone formation and remodeling.
Results
Reconstructed microCT images show increased bone formation, remodeling, and integration in HA/ β -TCP-BMP scaffolds compared to virgin HA/ β -TCP scaffolds. Histological analysis showed increased bone formation but decreased osteoconduction in HA/ β -TCP-BMP scaffolds. Nanoindentation showed no effect of BMP on hardness nor elastic modulus of bone formed on the scaffolds.
Discussion/Conclusions
HA/ β -TCP scaffolds with/without BMP are highly biocompatible and can successfully augment and accelerate the regeneration and remodeling of bone in critically sized long bone defects in a rabbit model. However, the data in this study show both improvement and detriment with the addition of BMP. Therefore, further studies must be performed. Ideally, eventual translation of this research to humans would eliminate the need for allograft and/or autograft in large bony defects and allow for a customizable 3D scaffold material relative to patient needs.
