BACKGROUND: Bone tissue engineering plays a very important role in the repair of bone defects, which can deliver bioactive substances, promote bone tissue growth and repair bone defects. Bone scaffolds act as one of the three elements of bone tissue engineering. Three-dimensional (3D) printing technology can achieve individualized bone tissue repair through customized artificial bone preparation.OBJECTIVE: To analyze the biological characteristics of several commonly used bone tissue engineering scaffolds and to explore the application of 3D printing technique in the construction of bone tissue engineering scaffolds.METHODS: The literatures of PubMed and Wanfang database related to bone tissue engineering scaffold materials and 3D printing technology were retrieved from 2005 to 2016. The Keywords were tissue engineering scaffold, bone defects,polymer materials, bioceramics, metal materials, composite materials, 3D printing in English and Chinese, respectively,which would appear simultaneously in title and abstract. Repetitive articles were excluded and finally 65 articles were included in result analysis.RESULTS AND CONCLUSION: The commonly used bone tissue engineering scaffold materials include polymer materials (natural and macromolecule polymeric materials), bioceramics, and metal materials. According to the characteristics of the materials, composite materials made of different materials can compensate for the shortcomings of a single material, and then developed into new tissue engineering scaffold materials. For the tissue engineering bone production, 3D printing technologies include melt deposition technology, selective laser sintering technology, low temperature deposition manufacturing technology, and etc. When the 3D printing technology is used to prepare a bone tissue engineering scaffold, the use of powder or adhesive must have limited conditions, such as flowability, stability and wettability. Powder materials used for 3D printing can be divided into synthetic polymers, natural macromolecules,bioceramics and their mixtures, with different advantages and disadvantages. Ultimately, the bone engineering scaffolds produced by 3D printing technology have unique advantages in mechanics, structure and individuality, and have wide application prospect in the manufacture of bone scaffolds.

Objective:To compare the effectiveness, safety and postoperative recurrence of percutaneous nephrolithotomy (PCNL) with Holmium laser for upper urinary calculi in Uyghur and Han pediatric patients.Methods:The data of 123 Uyghur and 71 Han pediatric patients with upper urinary calculi admitted to First People's Hospital of Kashgar, Xinjiang and Beijing Friendship Hospital, Capital Medical University respectively, from August 2018 to August 2023, were retrospectively reviewed. The gender [males 73 (59.3%) vs.46 (64.8%) ], laterality (single/bilateral: 94/29 vs. 59/12), hydronephrosis [115 (93.5%) vs. 63 (88.7%)] and anatomical abnormalities [2(1.6%) vs. 5(7.0%)] of Uyghur and Han children were not statistically significant ( P>0.05). Uyghur children were older than Han children [5 (3, 7) vs. 3 (2, 6) years old], with a higher proportion of emaciated children [27 (21.9%) vs. 6 (8.5%) cases], a larger maximum stone diameter [(2.30±0.78) vs. (1.96±1.50) cm] and a lower proportion of multiple stones [46 (37.4%) vs. 52 (73.2%) cases] (all P<0.05). All the patients were treated with Holmium laser PCNL. The channels of the procedures in this study include F12-18 small channels and visual puncture channels. The operation datas, stone-free rate (SFR), complication rate (CR) and stone recurrence rate of the two groups were compared. Meanwhile, multiple logistic regression analysis was used to explore the factors influencing these indicators. Results:The operation time for Uyghur children was significantly longer than that of Han children [75.0 (58.0, 93.0) vs. 30.0 (20.0, 48.8) min]. Additionally, a greater proportion of Uyghur children underwent PCNL with F12-18 small channels than Han children [119 (96.7%) vs. 49(69.0%) cases]. The SFR [89.4%(110/123)vs.88.7%(63/71)], and postoperative CR [31.7%(39/123)vs. 26.8%(19/71)] in Uyghur and Han patients were not significantly different (all P>0.05). The recurrence rate in Uyghur children was higher than that observed in Han children [28.1%(25/89) vs. 15.6%(10/64), P=0.033]. The multivariate logistic regression analysis results indicated that the maximum stone diameter was an independent risk factor for SFR in both groups ( OR=0.401, 95% CI 0.191-0.842, P=0.016). Similarly, maximum stone diameter ( OR=1.896, 95% CI 1.088-3.304, P=0.024) and multiple stones ( OR=3.225, 95% CI 1.409-7.384, P=0.024) were identified as independent risk factors for CR. Ethnicity was not independent risk factor for SFR( OR=0.679, 95% CI 0.215-2.140), CR( OR=1.047, 95% CI 0.495-2.215) and stone recurrence rate( OR=0.820, 95% CI 0.285-2.356, all P>0.05). Conclusions:In comparison to Han pediatric patients during the same period, Holmium laser PCNL had similar SFR and CR for treating Uyghur children with upper urinary calculi, who were older, more emaciated and had larger average stone diameters. The higher postoperative recurrence rate of Uyghur children is likely to be associated with higher stone burden. The multivariate logistic regression analysis results showed that ethnicity was not an influential factor in SFR, complication rates, and stone recurrence rates. The findings need to be further validated in larger prospective cohort studies.