High-strength scaffolds for bone regeneration

Repair of large skeletal defects that are intrinsic to skeletal stability represents the greatest challenge for orthopaedic surgeons. ¹ Despite extensive research to replicate the mechanical properties of bones in a synthetic alternative none are commercially available. This research reports a practical solution to this challenge by applying the extrusion process used for the production of ceramic exhaust catalysts to calcium phosphate bone graft substitutes. Clay-like hydroxyapatite (HA) pastes formed in a high-shear mixer were extruded through a complex die, dried and finally fired to form highly porous and strong monoliths. Five different samples were produced with differing wall thickness, cell pitch and porosity. The resulting HA monoliths had primary axis compressive strength of 142–265 MPa and compressive modulus of 3·9–4·4 GPa. These values well correspond to cortical bone and are exceptional given the bulk porosity of the samples varied from 54·4% to 63·1%. All samples supported the proliferation of MG63 cells with only a marginal difference between the samples. It is expected that calcium phosphate-based extruded monoliths will provide a possible commercial alternative to autograft and allograft for large structural bone defects.