Most bone adhesives are not able to withstand stresses that materials would find in vivo. Synthetic adhesives often pose biocompatibility problems, leading to necroses or higher infection rates.
Researchers at the University of Illinois Urbana-Champaign are investigating improvements to the mechanical properties of polyurethane adhesives by combining them with hydroxyapatite, thus producing a 4-fold increase in tensile strength of the glued bone, with respect to conventional bone cement.
The polyurethane in this case is moisture-curable and mixed with water by ultrasonication, to create a foamy paste. Separately, nanoscale hydroxyapatite is sonicated with water and added to the paste, forming a hierarchical structure with micron-sized voids and nano-sized hydroxyapatite particles, which can then be brushed on the bone.
Good biocompatibility of the material in vitro and in vivo ensures the applicability of the adhesive. Polyurethanes are known to be degraded over time by enzymes, providing another favorable characteristics for surgical applications.
Gluing bones with polyurethane hierarchical nanocomposites. Stefano Tonzani, Materials Views, June 21, 2012.
A polyurethane-based nanocomposite biocompatible bone adhesive. Schreader KJ et al, Journal of Applied Polymer Science, June 14, 2012.