Effects of Synergistic Reinforcement and Absorbable Fiber Strength on Hydroxyapatite Bone Cement

Published

September 1, 2005

Author(s)

Yu Zhang, Hockin D. Xu

Abstract

Approximately a million bone grafts are performed each year in the United States, and this number is expected to increase rapidly as the population ages. Calcium phosphate cement (CPC) can intimately adapt to the bone cavity and harden to form resorbable hydroxyapatite with excellent osteoconductivity and bone-replacement capability. The objective of this study was to develop a strong CPC using synergistic reinforcement via suture fibers and chitosan, and to determine the fiber strength-CPC composite strength relationship. Biopolymer chitosan and cut suture filaments were randomly mixed into CPC. Both suture filaments and composite were immersed in a physiological solution. After 1 d, cement flexural strengths (mean sd; n = 6) were: (2.7 0.8) MPa for CPC control; (11.2 1.0) MPa for CPC-chitosan; (17.7 4.4) MPa for CPC-fiber composite; and (40.5 4.8) MPa for CPC-chitosan-fiber composite. They are significantly different from each other (Tukey s at 0.95).Compared to CPC control, the strength increase from chitosan and fiber together was not only much more than that from either fiber or chitosan alone, it was also more than the sum of the individual strength increases from fiber and chitosan. The composite strength became (9.8 0.6) MPa at 35 d and (4.2 0.7) MPa at 119 d, comparable to reported strengths for sintered porous hydroxyapatite implants and cancellous bone. After suture fiber dissolution, long macropore channels were formed in CPC suitable for tissue ingrowth. A semi-empirical relationship between suture fiber strength SF and composite strength SC were obtained: SC = 14.1 + 0.047SF, with R = 0.92. In summary, this study achieved substantial synergistic effects by combining random suture filaments and chitosan in CPC. This may help extend the use of the moldable, in situ hardening hydroxyapatite to moderate stress-bearing orthopaedic applications.

Citation

Journal of Biomedical Materials Research Part A

Pub Type

Journals

Keywords

absorbable fiber, bone repair, calcium phosphate cement, high strength, hydroxyapatite, macropores

Citation

Zhang, Y. and Xu, H. (2005), Effects of Synergistic Reinforcement and Absorbable Fiber Strength on Hydroxyapatite Bone Cement, Journal of Biomedical Materials Research Part A (Accessed April 24, 2024)