Objective To investigate the feasibility and primary clinical outcomes of a kind of independent research and development customized 3D printed external fixator in the treatment of tibial fracture.Methods Data of 7 tibial fracture patients who were treated using computer-assisted reduction and 3D printing technique including a new kind of customized external fixator with automatical reduction function from December 2013 to November 2015 were retrospectively analyzed.There were 5 males and 2 females in this cohort.The age of the patients ranged from 25 to 49 years old,with an average age of 38.1 years old.The procedure was as follows.At first,two or three pins were placed separately into the distal and proximal tibia away from fracture site.Then,the CT scanning was performed on the fractured tibia.According to the CT scanning data,the external fixator was designed by computer software and manufactured by the 3D printing technique.The reduction of tibial fracture was achieved automatically after the 3D printed external fixator was connected to the inserted pins.Finally,the accuracy of reduction was assessed by postoperative X-ray image.During the different fracture healing course,the stress environment could be dynamically adjusted by screwing or unscrewing the nuts to fulfill rigid fixation,compression fixation or elastic fixation for the bone healing.Results All the 7 cases had obtained successful reduction by only one time operation with the 3D printed external fixators.The average lateral angulation was 1.42°± 1.13°,and the average anteroposterior angulation was 1.65°± 1.36°,while the average lateral displacement was 1.38± 1.44 mm,and the average anteroposterior displacement was 1.83± 1.30 mm,which were measured from postoperative X-ray image.The individual durations of the operation were 9 min,8 min,9 min,1.5 min,1.4 min,1.4 min and 2.4 min,respectively.All fractures had achieved bony union in 19-25 weeks after operation,with an average time of 21.4±1.6 weeks.All patients were followed up for 6 months when removal of the external fixator,and no refracture occurred.Conclusion The customized 3D printed external fixator has the function of automatical reduction.In addition,it can provide three kinds of fixation modes,which are rigid fixation,compression fixation and elastic fixation.It has the advantages of simple operation,accurate reduction,reasonable fixation,etc.

Objective To investigate the killing effect of polymethylmethacrylate (PMMA) on spinal metastasis of transplanted VX2 carcinoma in experimental rabbit models. Methods Spinal metastasis of transplanted VX2 carcinoma model was successfully established in 18 rabbits. The experimental rabbits were randomly and equally divided into three groups with 6 rabbits in each group. Under CT guidance , PMMA or saline was injected into the center of VX2 tumor; in group A 0.3 ml of PMMA was used, in group B 0.1 ml of PMMA was used and in group C (control group) 0.3 ml saline was used. Twenty-four hours after the injection, the animals were sacrificed. Four tissue samples were obtained from the sites at 1 mm , 5 mm, 10 mm and 15 mm away from the PMMA mass in each rabbit of group A and group B , while four tissue samples were collected from different four sites from the tumor ’s center to border in each rabbit of group C. TdT-mediated dUTP nick-end labeling (TUNEL) method was used to determine the tumor cell apoptosis rate. Results After successful establishment of rabbit model, injection of PMMA was performed in sixteen among the eighteen rabbits. Technical success rates were 83.3% in both group A and B, and the success rate was 100% in group C. The difference in technical success rate was not significant. The mean tumor cell apoptosis rates of spinal VX2 carcinoma at 1 mm, 5 mm and 10 mm away from the PMMA mass in group A were (65.75±18.81)%, (50.00±14.24)% and(14.95±8.98)% respectively. The mean apoptosis rate in the control group was (9.79 ±5.24)%; the differences between the group A and the control group were statistically significant (P<0.05). The mean tumor cell apoptosis rate of spinal VX2 carcinoma at 15 mm away from the PMMA mass in group A was (10.30 ±8.13)%, which was not significantly different with that of the control group. The mean tumor cell apoptosis rates of spinal VX2 carcinoma at 1 mm and 5 mm away from the PMMA mass in group B were (49.20±15.57)% and(17.75±9.28)% respectively, which was significantly different with that of the control group(P<0.05); the mean tumor cell apoptosis rates at 10 mm and 15 mm away from the PMMA mass in group B were not significantly different with those of the control group. Statistically significant differences in the mean tumor cell apoptosis rates determined at 1 mm, 5 mm and 10 mm away from the PMMA mass existed between group A and group B(P<0.001). Conclusion PMMA can promote the apoptosis of tumor cells, properly increasing the injected amount of PMMA can enlarge the extent of tumor cell apoptosis.

This article introduced the application of trajectory model in epidemiological study on fat development in sixty teenagers.Results showed that fat developing trend on three trajectories-normal fat group,high fat group and very high fat group,with independently different developing trend.Trajectory model seemed a suitable model for fitting the longitudinal data with heterogeneity.