Development of macroporous eggshell derived apatite bone cement for non-load bearing defect repair in orthopedics

Abstract

A novel and easy approach was attempted to developed a ready to use injectable macroporous apatite bone cement derived from eggshell under physiological conditions where, the solid phase contains hydroxyapatite and eggshell derived β-tricalcium phosphate and the liquid phase is the biopolymeric solution (gelatin and chitosan for improving injectability) with disodium hydrogen phosphate (as binding accelerator) in diluted acetic acid. Also, polysorbate as liquid porogen is incorporated in liquid phase (to enhance cement porosity) and it was compared with the cements containing mannitol as solid porogen. All are mixed in an optimized composition to get desired bone cement. The so-formed cements set within clinically acceptable setting time (≤20 min) and are good injectable (>75%), along with stability at physiological pH (∼7.3–7.4). The apatite phased bone cement formed when the after-set cement immersed in phosphate buffer solution (PBS) and incubated for 7 days at physiological conditions, confirmed by X-ray diffraction and Fourier transform Infrared spectroscopy analysis. The cements hold acceptable compressive strength (2.5–4 MPa), within the range of trabecular bone and are also degradable (19–25%) in PBS and simulated body fluid within 70 days. The average pore size of the eggshell derived apatite bone cements (ESDAPCs) falls in between 50 and 250 μm with interconnectivity, confirmed by scanning electron microscopy and micro-CT analysis verified its macroporous nature. The viability and alkaline phosphatase activity of MG63 cells incubated with the ESDAPCs was found to be significantly higher after 3rd and 14th day when compared to their respective controls. Also, the MG63 cells were fully grown over the surface of the ESDAPCs with increased proliferation and extended filopodia. In conclusion, the developed ESDAPC has the ability to become a potential material for repairing low or non-load bearing defects in orthopaedic applications.