Macroporous Scaffold of Premixed Calcium Phosphate Bone Cement: Mechanical Properties and Cell Response
Hockin D. Xu, Lisa E. Carey, Carl G. Simon Jr.
Calcium phosphate cement (CPC) sets in the bone cavity to form bioresorbable hydroxyapatite and is highly promising for orthopaedic applications. The objective of this study was to develop premixed macroporous CPC scaffolds for cell infiltration and tissue ingrowth, and to improve the scaffold strength by suture fiber reinforcement. Premixed CPC was developed to avoid powder-liquid mixing during surgery, shorten surgical time and improve graft properties. Water-soluble mannitol particles were mixed into CPC with a non-aqueous liquid. The premixed paste set when immersed in a physiological solution. At 30 % and 40 % mannitol mass fractions, flexural strengths (mean sd; n = 5) of premixed scaffold were (2.1 0.8) MPa and (0.7 0.2) MPa, respectively. With suture reinforcement, they significantly increased to (3.9 1.4) MPa and (1.8 0.8) MPa, respectively (Tukey s at 0.95). At these mannitol fractions, pore volume fractions (mean sd; n = 5) reached (68.6 0.7) % and (74.7 1.2) %, respectively.Osteoblast cell viability was assessed by measuring the mitochondrial dehydrogenase, and the absorbance at 450 nm (arbitrary units) was (0.51 0.08) for premixed CPC with macropores, similar to (0.54 0.09) for a biocompatible, non-premixed CPC control without macropores (p > 0.1). Cells colonized inside the macropores of the premixed scaffold and attached to the hydroxyapatite crystals via cytoplasmic extensions. Cell-cell interactions were established to form three-dimensional cell webs inside the pores. In summary, using fast-dissolving mannitol and slow-dissolving suture, a premixed CPC scaffold was developed with strength similar to reported strengths of sintered porous hydroxyapatite and cancellous bone, and biocompatibility similar to a biocompatible non-premixed CPC. The new self-hardening and strong cement avoided the need for on-site powder-liquid mixing, formed macroporous hydroxyapatite, and should facilitate cell infiltration and bone ingrowth in orthopedic repairs.
, Carey, L.
and Simon, C.
Macroporous Scaffold of Premixed Calcium Phosphate Bone Cement: Mechanical Properties and Cell Response, Journal of Orthopaedic Research, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852439
(Accessed June 8, 2023)