ABSTRACT
BACKGROUND: Porosity has been proven to improve the stability of orthopedic implants, and the architecture of pores is considered as a significant factor to improve the osseointegration of implants. OBJECTIVE: To introduce the research advance in porous architecture. METHODS: WOS database was searched for the articles addressing the porous structure of the implants published from January 2000 to April 2016 using the keywords of scaffold, pore size, porosity, osteogenesis. The literatures were screened according to the inclusion and exclusion criteria.RESULTS AND CONCLUSION: (1) The stability of traditional implants cannot meet the requirements in some specific circumstances, while the implants with porosity can improve the stability due to its osteogenesis ability. (2) Porous structure is a hotspot, and the osseointegration of porous implants in vivo is explored through series of in vitro and in vivo experiments. (3) It has been shown that higher porosity, proper pore size, microporous morphology and microstructure of the pore wall may contribute to the growth and differentiation of bone tissue under enough mechanical support. (4) However, most studies on the porous implants are still on the in vivo and animal experimental stage, and its promoting effects on the osteogenesis and bone in-growth are needed to be investigated in depth.
ABSTRACT
BACKGROUND:Titanium alloy, a commonly used bone biomaterial, holds good biocompatibility and proper mechanical properties, but without osteointegration ability. Surface bioactive coating of titanium alloy can overcome such problems. OBJECTIVE:To review the application progress of surface bioactive coating on titanium alloys, and to explore the mechanism underlying its osteogenic induction. METHODS:PubMed and CNKI databases were searched for literatures concerning surface bioactive coating on titanium alloys published from January 2000 to March 2016, using the keywords oftitanium, titanium alloys, coating, surface modification, bonein English and Chinese, respectively. Through preliminary analysis, 42 eligible articles were selected. RESULTS AND CONCLUSION:The surface modification method has undergone the transition from surface roughening, oxidation, acidification treatment to the most widely used biomimetic coating technology. The surface biomimetic coatings of titanium alloys mainly include hydroxyapatite, bioactive glass, zeolite, which have been developed from a single coating to the composite coatings and gradient coatings. What's more, the bioactive factor or/and metal ions in the coating can improve the osteointegration of surface coating. Surface modification for titanium alloys is a complex process, during which, both the osteogenesis ability and the bonding strength between the coating and its substrate cannot be ignored. Improving the fabrication method of existing coatings and exploring new materials of biomimetic coatings are critical to achieve a high-quality surface coating modification.
ABSTRACT
BACKGROUND:Surface modification of titanium surface to improve its biological activity is the research hotspot. Strontium-doped coating is considered to be an effective approach to promote the implant osseointegration. OBJECTIVE:To introduce the research progress of strontium-modified biomedical titanium al oys.METHODS:Articles related to the medical titanium al oys modified with strontium published from January 2000 to April 2016 were retrieved from CNKI and PubMed databases. The keywords were“titanium (Ti), strontium (Sr), bone, osteogenic”in Chinese and English, respectively. RESULTS AND CONCLUSION:Titanium al oys have been widely used in bone implantation because of their good biocompatibility and similar elasticity modulus with human bones. However, pure titanium al oys have poor bioactivity which leads to weak bone-implant contact. Surface modification is a good approach to enhance implant osseointegration. Sr-doped surface treatment can promote new bone formation and osseointegration. Most of the studies about Sr-doped modification are ongoing at the extracorporeal and animal experiment stage;therefore, further investigation is required to seek rapid, stable, available, safe and effective methods.