The effect of anodised treatment on zirconium implant at early stages: a preliminary in vivo and in vitro characterization

PELLEJERO, JULIANA; CARLOS VOTTOLA; ANDREA GOMEZ SANCHEZ; MATIAS BACA; CERE, SILVIA; MARÍA ROSA KATUNAR; ENRIQUE MARTINEZ-CAMPOS; JOSEFINA BALLARRE

Montreal

Congreso; Word Biomaterials Congress; 2016

Most metals used as cementless implants undergo some kind of surface modification before clinical insertion. These modifications are performed to promote biological reactions at the interface influencing principally in the biological events that lead to bone formation.Cementless prosthesis have been suggested to have the minimal stress shielding and even superior survival rate which make them the primary choice for young patients. A variety of surface modifications have been studied and applied to implants to achieve long-term fixation to the host bone by osseointegration It is known that the texturing and /or chemical alterations of material surfaces may lead to long-term integration in bone, so implant topography is critical to the success of bone-anchored implants. Zirconium (Zr) is an ideal metal for intra-osseous implants for its favorable resistance to corrosion, osseointegration capability and lower metal ions migration to the biological surroundings when it is compared with stainless steel and titanium alloys. Zr and its alloys have been studied for being used in the nuclear power industry and have been recently commercialized for its use in medical implants, especially for total knee and hip replacements after hydrothermally grown oxide. The aim of this study is focused on the first events that take place around anodized Zr implants. The surface in vitro cytocompatibility was evaluated by observing cell adhesion, proliferation, and differentiation using pre mioblastic C2C12 cell line . This cell line was treated with a lentivirus with Green Fluorescent Protein (GFP) allowing cell visualization over opaque biomaterials, showing an optimum growth and cell behavior. .Our in vitro results highlight that anodisation treatment at 60V allowed stronger cell attachment promoting cell proliferation at early stages. Evaluation of cell morphology through fluorescent microscopy showed an interesting relationship between cell differentiation and material surface. In vivo implant osseointegration was evaluated by histomorphometrics characteristics of new bone formation. Male Wistar rats were employed and the implants Zr0 (without treatment),Zr30 (with anodized 30V) and Zr60(with anodized 60V) were placed by press fit into femur extending into the medullar canal. The biological events were evaluated 15 and 30 days after surgery.These results showed that Zr implants had an optimal new bone density distribution, and optimal bone?implant osseointegration 15 and 30 days after surgery. The thickness of the new bone showed that anodized at 60V treatment improved notoriously the characteristic of the new bone growth just 15 days after surgery. The profile of bone formation was analyzed by polychrome fluorescent labeling using calcium-binding fluorochromes and the results showed that bone thickness is accompanied by an significant increased in MAR parameter at early stages.In conclusion, it can be speculated that coupling the positive results obtained both in vitro and in vivo conditions of anodisation treatment on Zr features can be beneficial for future orthopedic applications.