Reticulated ceramic composites for hard tissue replacements

To overcome the material limitations of skeletal implants and to improve long-term clinical performance, a unique composite implant is proposed that can facilitate natural tissue regeneration and provide mechanical support during healing. This implant design is based on biocompatible reticulate structure similar to trabecular bone that is infiltrated with a biodegradable polymer. To demonstrate the potential of the proposed implant design, bioinert aluminum oxide (Al₂O ₃) reticulated ceramics with uniform open pore size distributions of 150 and 1700 μm were obtained from a commercial supplier. A biodegradable aliphatic polyester, poly(ε-caprolactone), was infiltrated into the pores of the ceramics and polymerized by a thermally catalyzed [175°C, 5 hr, N ₂] ring-opening mechanism with the Lewis acid sites on the surface of the reticulated ceramic. As compared to conventionally polymerized biodegradable polyesters, this polymerization mechanism avoids the use of cytotoxic catalysts and can result in improved interfacial adhesion. To evaluate their clinical potential, the mechanical properties of the original reticulate structures and the composite products were evaluated using four point bend rupture testing on wet, polished (9 μm) samples (25×5×2 mm). Infiltrating the degradable polymer into the reticulate structure results In dramatic improvements in strength (σ_max~26.0 MPa, >400%), ductility (δ-1.83%, >250%) and elastic modulus (1.24 GPa, >450%). Fracture surface analysis indicates that these composite materials fail due to porous defects (~100 μm, SEM) in the supporting struts of the reticulate ceramic