A quantitative technique for comparing synthetic porous hydroxyapatite structures and cancellous bone

O’Kelly, Kevin; Tancred, D. C.; McCormack, B. A. O.; Carr, Alan

doi:10.1007/bf00119732

Cited by 24 publications

(17 citation statements)

References 28 publications

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“…This approached the reported flexural strength of 2-11 MPa for sintered porous hydroxyapatite implants [4] and a tensile strength of 3.5 MPa for cancellous bone [50]. Cancellous bone had an elastic modulus of about 0.30 GPa [51], compared to about 1 GPa for the injectable CPC scaffold (Fig. 6).…”

Section: Article In Presssupporting

confidence: 55%

Injectable and macroporous calcium phosphate cement scaffold

et al. 2006

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Section: Article In Presssupporting

confidence: 55%

Injectable and macroporous calcium phosphate cement scaffold

et al. 2006

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“…In the present study, the macroporous CPC scaffold had a strength of about 4 MPa, matching the reported 3.5 MPa for cancellous bone [38]. Macroporous CPC had elastic modulus of about 500 to 1000 MPa, which compares with the reported elastic modulus of approximately 300 MPa for cancellous bone [39]. A literature search did not found the work-of-fracture value of cancellous bone.…”

Section: Discussionsupporting

confidence: 80%

Bone regeneration via novel macroporous CPC scaffolds in critical-sized cranial defects in rats

et al. 2014

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Objectives Calcium phosphate cement (CPC) is promising for dental and craniofacial applications due to its ability to be injected or filled into complex-shaped bone defects and molded for esthetics, and its resorbability and replacement by new bone. The objective of this study was to investigate bone regeneration via novel macroporous CPC containing absorbable fibers, hydrogel microbeads and growth factors in critical-sized cranial defects in rats. Methods Mannitol porogen and alginate hydrogel microbeads were incorporated into CPC. Absorbable fibers were used to provide mechanical reinforcement to CPC scaffolds. Six CPC groups were tested in rats: (1) Control CPC without macropores and microbeads; (2) Macroporous CPC + large fiber; (3) Macroporous CPC + large fiber + nanofiber; (4) Same as (3), but with rhBMP2 in CPC matrix; (5) Same as (3), but with rhBMP2 in CPC matrix + rhTGF-β1 in microbeads; (6) Same as (3), but with rhBMP2 in CPC matrix + VEGF in microbeads. Rats were sacrificed at 4 and 24 weeks for histological and micro-CT analyses. Results The macroporous CPC scaffolds containing porogen, absorbable fibers and hydrogel microbeads had mechanical properties similar to cancellous bone. At 4 weeks, the new bone area fraction (mean ± sd; n = 5) in CPC control group was the lowest at (14.8 ± 3.3)%, and that of group 6 (rhBMP2 + VEGF) was (31.0 ± 13.8)% (p < 0.05). At 24 weeks, group 4 (rhBMP2) had the most new bone of (38.8 ± 15.6)%, higher than (12.7 ± 5.3)% of CPC control (p < 0.05). Micro-CT revealed nearly complete bridging of the critical-sized defects with new bone for several macroporous CPC groups, compared to much less new bone formation for CPC control. Significance Macroporous CPC scaffolds containing porogen, fibers and microbeads with growth factors were investigated in rat cranial defects for the first time. Macroporous CPCs had new bone up to 2-fold that of traditional CPC control at 4 weeks, and 3-fold that of traditional CPC at 24 weeks, and hence may be useful for dental, craniofacial and orthopedic applications.

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“…34,39 Cortical bone has a reported flexural elastic modulus of about 12.8 GPa, 40 and cancellous bone has an elastic modulus of about 0.30 GPa. 41 The cement with suture and chitosan developed in the present study possessed an elastic modulus of 3.2 GPa at 1 day and 3.0 GPa at 35 days, within the range for cortical bone and cancellous bone.…”

Section: Discussionmentioning

confidence: 95%

Effects of synergistic reinforcement and absorbable fiber strength on hydroxyapatite bone cement

Zhang

2005

J Biomedical Materials Res

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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-day immersion, 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 +/- 5.8) MPa for CPC-chitosan-fiber composite. They are significantly different from each other (Tukey's at 0.95). The strength increase from chitosan and fiber together in CPC was much more than that from either fiber or chitosan alone. The composite strength became (9.8 +/- 0.6) MPa at 35-day immersion and (4.2 +/- 0.7) MPa at 119 days, 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 cell migration and tissue ingrowth. A semiempirical relationship between suture fiber strength S(F) and composite strength S(C) were obtained: S(C) = 14.1 + 0.047 S(F), 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 orthopedic applications. The long macropore channels in CPC should be advantageous for cell infiltration and bone ingrowth than conventional random pores and spherical pores.

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A quantitative technique for comparing synthetic porous hydroxyapatite structures and cancellous bone

Cited by 24 publications

References 28 publications

Injectable and macroporous calcium phosphate cement scaffold

Injectable and macroporous calcium phosphate cement scaffold

Bone regeneration via novel macroporous CPC scaffolds in critical-sized cranial defects in rats

Effects of synergistic reinforcement and absorbable fiber strength on hydroxyapatite bone cement

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