Fast-Setting Calcium Phosphate Scaffolds With Tailored Macropore Formation Rates for Bone Regeneration

Published

March 1, 2004

Author(s)

Hockin D. Xu, Shozo Takagi, Janet Quinn, Laurence C. Chow

Abstract

Calcium phosphate cement (CPC) is highly promising for craniofacial and orthopedic repair due to its ability to self-harden in situ to form hydroxyapatite with excellent osteoconductivity. However, its low strength, long hardening time, and lack of macroporosity limit its use. This study aimed to develop fast-setting and anti-washout CPC scaffolds with high strength and tailored macropore formation rates. Chitosan, sodium phosphate and hydroxypropyl methylcellulose (HPMC) were used to render CPC fast-setting and resistant to washout. Absorbable fibers and mannitol porogen were incorporated into CPC for strength and macropores for bone ingrowth. Flexural strength, work-of-fracture and elastic modulus were measured vs. immersion time in a physiological solution. Hardening time (mean sd; n = 6) was (69.5 2.1) min for CPC-Control, (9.3 2.8) min for CPC- HPMC-Mannitol, (8.2 1.5 ) min for CPC-Chitosan-Mannitol, and (6.7 1.6) min for CPC-Chitosan-Mannitol-Fiber. The latter three compositions were resistant to washout, while the CPC-Control paste showed washout in a physiological solution. Immersion for 1 d dissolved mannitol and created macropores in CPC. CPC-Chitosan-Mannitol-Fiber scaffold had a strength of (4.6 1.4) MPa, significantly higher than (1.2 0.1) MPa of CPC-Chitosan-Mannitol scaffold, and (0.3 0.2) MPa of CPC-HPMC-Mannitol scaffold (Tukey's). The strength of CPC-Chitosan-Mannitol-Fiber scaffold was maintained up to 42 d and then decreased due to fiber degradation. Work-of-fracture and elastic modulus showed similar trends. Long cylindrical macropore channels were formed in CPC after fiber dissolution. The resorbable, fast-setting, anti-washout and strong CPC scaffold should be useful in craniofacial and orthopedic repairs. The novel method of combining fast- and slow-dissolution porogens/fibers to produce scaffolds with high strength and tailored macropore formation rates to match bone healing rates may have wide applicability to other biomaterials.

Citation

Journal of Biomedical Materials Research Part A

Volume

68A

Issue

No. 4

Pub Type

Journals

Keywords

absorbable fibers, anti-washout, calcium phosphate cement, craniofacial and orthopedic repair, fast-setting, hydroxyapatite, reinforcement

Citation

Xu, H. , Takagi, S. , Quinn, J. and Chow, L. (2004), Fast-Setting Calcium Phosphate Scaffolds With Tailored Macropore Formation Rates for Bone Regeneration, Journal of Biomedical Materials Research Part A (Accessed November 9, 2024)