Osteoanabolic Implant Materials for Orthopedic Treatment

Abstract

Osteoporosis is becoming more prevalent due to the aging demographics of many populations. Osteoporotic bone is more prone to fracture than normal bone, and current orthopedic implant materials are not ideal for the osteoporotic cases. A newly developed strontium phosphate (SrPO4 ) coating is reported herein, and applied to Ti-29Nb-13Ta-4.6Zr (wt%), TNTZ, an implant material with a comparative Young's modulus to that of natural bone. The SrPO4 coating is anticipated to modulate the activity of osteoblast (OB) and osteoclast (OC) cells, in order to promote bone formation. TNTZ, a material with excellent biocompatibility and high bioinertness is pretreated in a concentrated alkaline solution under hydrothermal conditions, followed by a hydrothermal coating growth process to achieve complete SrPO4 surface coverage with high bonding strength. Owing to the release of Sr ions from the SrPO4 coating and its unique surface topography, OB cells demonstrate increased proliferation and differentiation, while the cellular responses of OC are suppressed, compared to the control case, i.e., bare TNTZ. This TNTZ implant with a near physiologic Young's modulus and a functional SrPO4 coating provides a new direction in the design and manufacture of implantable devices used in the management of orthopedic conditions in osteoporotic individuals.

Modification of titanium surface via Ag-, Sr- and Si-containing micro-arc calcium phosphate coating

“…For instance, implant materials have to correspond to certain physical, chemical and mechanical properties. What is more, they have to be biocompatible with surrounding tissues, namely they should not be the cause of allergic and/or inflammatory reactions in the body [1,2].…”

Simultaneously improving the corrosion resistance and strength of magnesium via low levels of Zn and Ge additions

“…Magnesium (Mg) alloys have the lowest density (~1.74 g/cm 3 ) of the engineering metals, approximately 65% the density of aluminium alloys and 25% that of steels [1][2][3]. The high specific strength of Mg alloys makes them attractive materials for the demands of lightweighting in transport and consumer electronics [1][2][4][5], whilst Mg alloys have also been increasingly studied as biomedical components due to their biocompatibility and bioresorbability [6][7]. Since Mg alloys possess a negative electrode potential in aqueous environments (~ -1.3 to -1.8 V SCE ) [8][9], and high theoretical energy density [10][11], they have also been greatly sought for use as electrodes in primary battery systems [12][13].…”

Design and development of metallic biomaterials with biological and mechanical biocompatibility

“…Strontium phosphate (SrPO 4 ) coating after hydrothermal alkali treatment is also an effective way of enhancing the osteoanabolic function of TNTZ as well as that of CP‐Ti. Figure shows the increasing number of viable osteoblast (OB) on both TNTZ and CP‐Ti subjected to SrPO 4 coating (SrPO 4 ‐TNTZ and SrPO 4 ‐CP‐Ti) as compared with those on TNTZ and CP‐Ti without SrPO 4 coating (TNTZ and Cp‐Ti) due to the release of Sr 2+ ions.…”