Reconstruction of Load-Bearing Segmental Bone Defects Using Carbonate Apatite Honeycomb Blocks

Abstract

In a globally aging society, synthetic bone blocks are in increasing demand. An ideal synthetic bone block fuses early with bone and is replaced with new bone at a suitable speed while withstanding the weight load. Herein, we report carbonate apatite honeycomb (HC) blocks with superior mechanical strength, osteoconductivity, and bioresorbability compared to a clinically used synthetic porous block (control block). Three types of HC blocks were fabricated via the debinding of HC green bodies at 600, 650, and 700 °C and subsequent phosphatization, designated as HC-600, HC-650, and HC-700, respectively. The macropores in these HC blocks uniaxially penetrated the blocks, whereas those in the control block were not interconnected. Consequently, the HC blocks exhibited higher open macroporosities (18%–20%) than the control block (2.3%). In contrast, the microporosity of the control block (46.4%) was higher than those of the HC blocks (19%–30%). The compressive strengths of the HC-600, HC-650, HC-700, and control blocks were 24.7, 43.7, 103.8, and 38.9 MPa, respectively. The HC and control blocks were implanted into load-bearing segmental bone defects of rabbit ulnae. Uniaxial HC macropores enabled faster bone ingrowth than the poorly interconnected macropores in the control block. Microporosity in the HC blocks affected bone formation and osteoclastic resorption over a period of 24 weeks. The resorption of HC-650 corresponded to new bone formation; therefore, new bone with strength equal to that of the original bone bridged the separated bones. Thus, the HC blocks achieved the reconstruction of segmental bone defects while withstanding the weight load. The findings of this study contribute to the design and development of synthetic bone blocks for reconstructing segmental defects.

Crystalline Micro-Sized Carbonated Apatites: Chemical Anisotropy of the Crystallite Surfaces, Biocompatibility, Osteoconductivity, and Osteoinductive Effect Enhanced by Poly(ethylene phosphoric acid)

“…βTCP demonstrates pronounced resorption-remodeling behavior, but the dissolution rate of βTCP is sometimes faster than the rate of bone repair, leading to inflammation and unsatisfactory bone formation . aCAp is very close to BAp in chemical composition, , and in recent years, aCAp-based scaffolds for bone surgery and orthopedics have attracted increasing scientific attention. ,,− The majority of experimental findings indicative of successful implantations of aCAp scaffolds were correlated with their porosity, ,,− shape, and carbonate content. − …”

Innovations in Bioengineering Virtual Special Issue

“…The webinar featured talks from Prof. Molly Stevens and Prof. Ali Khademhosseini and is available on demand ( go.acs.org/OV ). As highlighted in Figure , this new virtual special issue includes papers on antimicrobials, gene and therapeutic delivery, − model systems and organs on a chip, − biomineralization and biopolymer synthesis, , regenerative medicine and scaffolds for tissue engineering, − and sensors. , Our authors come from around the worldAustralia, Brazil, Canada, China, Germany, India, Iran, Israel, Italy, Japan, Poland, Portugal, Singapore, Spain, Switzerland, and the United Statesand include leaders in the field alongside quite a number of rising stars. We were delighted with the insights revealed in this collection of papers.…”