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Peri-prosthetic infection and loosening of implants are major problems in orthopaedic and dental surgery. To address these issues, surface treatment methods for titanium implants have been improved by modifying the alkali and heat treatment. We have previously fabricated calcium-treated Ti metal that releases Sr ions (CaSr-Ti), which resulted in a higher in vitro osteogenic response and early in vivo bone bonding. Further, we developed a Ti metal that released both Sr and Ag ions (CaSrAg-Ti). In this study, we evaluated the antibacterial ability and osteogenic cellular response of CaSrAg-Ti and CaSr-Ti in vitro using rat bone marrow stromal cells (BMSCs) cultured on implant samples and extract mediums (EMs) made by immersing the implant samples in the medium. CaSrAg-Ti did not show cytotoxicity and was associated with a slightly higher osteogenic response when compared to CaSr-Ti, without inhibiting the effect of Sr. The osteogenic response was also observed in the cells cultured with the CaSrAg-Ti EM; however, the response was not as high as that of the cells on the CaSrAg-Ti implant sample. Significantly higher antibacterial activity was observed along with an antibacterial efficacy of more than 95% against methicillin-susceptible Staphylococcus aureus and Escherichia coli. The main advantages of our surface treatment are its simplicity and low cost. Therefore, our treatment is promising for clinical applications in orthopaedic or dental Ti-based implants with antibacterial and early bone-bonding abilities.

To overcome problems associated with loosening of orthopedic implants and surgical site infections, we developed a novel, titanium (Ti)-based material that releases both strontium and silver ions (CaSrAg-Ti) based on alkali-and-heat treatment. The results of commercially pure Ti (cp-Ti), Ti that releases Sr ions only (CaSr-Ti), and the novel CaSrAg-Ti material were compared. Mechanical tests were performed to evaluate the in vivo bonding properties of CaSrAg-Ti and the bone-implant contact (BIC) ratio in histological specimens was determined at 4 and 8 weeks after implantation in a rat femur. Also, the in vitro antibacterial activities of this material against methicillinsusceptible Staphylococcus aureus (MSSA) were evaluated after a 24 h incubation period by assaying colony-forming units. In addition, antibacterial activities were evaluated in vivo at 7 days after implantation in a rat subcutaneous pocket model. There was direct contact between the bone and CaSrAg-Ti in histological specimens and no apparent signs of argyrosis in any rat. The bone-bonding strength and the BIC ratio were increased by 2.7-and 2.3-fold for CaSrAg-Ti vs. cp-Ti at 4 weeks and 2.2and 2.0-fold at 8 weeks, respectively. As compared with cp-Ti, the number of viable MSSA remaining on CaSrAg-Ti was reduced by 100 ± 0% in vitro and 94.2 ± 6.9% in vivo. Ti that releases Sr and Ag ions is a promising material that exhibits both bone-bonding properties and anti-MSSA activities.

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Background To investigate the association between knee pain and risk factors including low back pain and to develop a score to predict new knee pain in an older population, using population-based longitudinal cohort data. Methods We collected a questionnaire on self-reported knee pain and demographic data in a systematic manner from community residents aged ≥ 50 years twice, at baseline, and after 5 years. Multivariate logistic regression analyses were performed to investigate the association between knee pain and risk factors and to build a predictive model that would enable calculation of the risk of the development of knee pain within 5 years. The model is presented in the form of score charts. Results A total of 5932 residents aged ≥ 50 years from the cohort of 9764 that completed the first questionnaire were enrolled in the second survey. After exclusions, paired data for the two time points an average of 5.4 years apart were analyzed for 4638 participants. Multivariate analyses showed older age, female sex, higher BMI, weight increase, lower mental health score, and higher back pain/disability score were independent risk factors for knee pain. The predictive score comprised six factors: age, sex, BMI, weight increase, mental health, and low back pain/disability. The risk of developing knee pain ranged from 11.0 to 63.2% depending on the total score. Conclusion This study demonstrated a significant association between knee and low back pain/disability along with other risk factors. The score we developed can be used to identify a population without any imaging modality who are at high risk of developing knee pain. Electronic supplementary material The online version of this article (10.1186/s13075-019-1884-0) contains supplementary material, which is available to authorized users.