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Poster: 98Appropriate Spatial Design With Titanium Oxide Layer Enhances BoneFormation and Its Maturation in Vivo*Atsushi Sugino - Nakashima Medical Co., Ltd. - Okayama, JapanKanji Tsuru - Kyushu University - Fukuoka, JapanSatoshi Hayakawa - Okayama University - Okayama, JapanYuki Shirosaki - Okayama University - Okayama, JapanChikara Ohtsuki - Nagoya University - Nagoya, JapanAkiyoshi Osaka - Okayama University - Okayama, Japan*Email: a.sugino@nakashima.co.jpSurface modification of the prosthesis is one of the important factors to achieve successfuloutcome on total hip and knee arthroplasty. Many researchers have been proposed surfacechemical treatments for providing titanium and its alloys with the apatite-forming abilitybecause the formation of apatite layer on the implant surface is an important events to showosteocompatibility. The authors previously reported that Ti-15Zr-4Nb-4Ta with 0.5 mm groovedeep and wide, and thermal oxidation at 500°C for 1 h provides effective surface to deposit abone-like apatite at the internal surface of grooves in the simulated body fluid. The purpose ofthis study is to evaluate in vivo osteocompatibility of Ti-15Zr-4Nb-4Ta alloy with 0.5 mm deepand wide grooves thermally oxidized at 500°C (GRAPE group), compared with Ti-15Zr-4Nb-4Ta alloy without that modification (SMOOTH group). Cylindrical Ti-15Zr-4Nb-4Taspecimens were cut spiral groove with deep and wide, and then thermally oxidized at 500°C for1 h in air. Male Japanese white rabbit weighting approx. 3.0 kg were anesthetized withKetamine containing Celactar. The defects 4.5 mm in diameter were made through the femoralcondyles of each femur, and then sterilized specimens were implanted to its defects. The rabbitswere sacrificed by overdose of sodium pentobarbital after 2, 4 and 8 weeks operation. Theextracted specimen with around tissue were fixed using a neutrally buffered formaldehydeaqueous solution, and then dehydrated, embedded in acrylic resin and cut to obtain thinsections. These sections were subjected to toluidine blue staining. Direct contact ratio betweenbone and materials were measured using Image J, and measured values were staticallyexamined with Mann-Whitney U test (p < 0.05). All of animal study was conducted under theguideline for animal experiment of Okayama University (Approval # OKU-2007324). Evenafter 2 weeks implantation, newly formed bone was observed on the surface of grooves ofGRAPE group, but not on the surface of SMOOTH group. Figure shows the macroscopicobservation around the interface between bone and Ti-15Zr-4Nb-4Ta alloy with 0.5 mm deepand wide grooves thermally oxidized at 500°C (GRAPE group) after 8 week operation. Notonly bone ingrowth but also matured osteonal bone could be observed in grooves of GRAPEgroup after 4 and 8 weeks operation. After 4 and 8 week implantation, direct contact ratio ofGRAPE group between bone and specimen showed significantly larger than SMOOTH groupby image analysis (p < 0.05). These data suggested that Ti-15Zr-4Nb-4Ta with 0.5 mm groovedeep and wide, and thermal oxidation at 500°C for 1 h could not only enhance theosteocompatibility of titanium alloy but also induce the maturation of bone tissue in vivo.Titanium-based implant with this type of extremely simple modification is expected to achievestrong fixation from early implantation periods.file:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]