Objective To investigate the epidemiological characteristics of tibial shaft fractures and analyze the effect of COVID-19 on it.Methods We retrospectively analyzed the clinical data of 1037 patients with tibial shaft fractures treated in the Second Affiliated Hospital of Air Force military Medical University from January 2012 to December 2021，which accounting for 28.44% (1 037/3 646) of tibiofibular fractures in the same period.That including 765 males (73.77%) and 272 females (26.23%)，with a male to female ratio of 2.81︰1，The average age was (40.91±18.99).The patients from January 2018 to December 2019 were assigned into pre-epidemic group，and those from January 2020 to December 2021 into post-epidemic group.The epidemiological characteristics of the patients were analyzed，such as sex，age，residence，cause of injury，fracture classification and so on.The differences of epidemiological characteristics between the two groups were analyzed and compared.Results Tibial shaft fracture mainly occurred in the age group of 41-50 years old in males and 31-60 years old in females (P＜0.05).The main causes of tibial shaft fractures were traffic accident injuries (55.26%) and fall injuries (23.92%).According to the AO classification of tibial shaft fractures，the constituent ratio of 42-A was the highest (48.99%)，followed by 42-B (26.71%)，and 42-C (24.30%) was the least.After the epidemic of COVID-19，the number of tibial shaft fractures decreased，but the average age was higher than that before the epidemic，and there was no significant difference (P＞0.05).There was no difference in the distribution of sex，residence，season，cause of injury and age between pre-epidemic group and postepidemic group (P＞0.05).There were significant differences in the mode of admission，the condition at the time of admission and AO classification between the two groups(P＜0.05).Conclusion Tibial shaft fractures accounted for 28.44% of tibiofibular fractures (1 037/3 646)，and most of them were male.The main causes of tibial shaft fractures were traffic accident injury and fall injury.In the AO classification of tibial shaft fracture，42-A is the most common type.After the epidemic of COVID-19，the number of tibial shaft fractures decreased，which was mainly admitted to the hospital by emergency.The number of emergency and criticaly patients decreased.And the type 42-A fractures were more common.

Objective To investigate the accuracy of artificial intelligence three-dimensional planning software in the selection of prosthetic size in total hip arthroplasty and analyze the factors affecting the accuracy.Methods A total of 57 patients (20 males and 37 females) who underwent unilateral primary total hip arthroplasty were selected.The X-ray and CT 3D reconstruction image data of the affected hip joint were collected from August 2021 to June 2022 before operation.A resident make a preoperative planning for each total hip arthroplasty using both the traditional templating and artificial intelligence three-dimensional preoperative planning software.We analyzed the accuracy of implant size prediction using two methods.The coincidence rate of the two methods was compared.At the same time，whether the BMI and leg length discrepancy of patients were the factors affecting the accuracy of measurement.Results The coincidence rates of 0，±1 and ±2 prosthesis size measurements of artificial intelligence planning on the acetabular side were 82.46%，10.53% and 7.01%，respectively.The acetabular concordance rate of traditional template was 42.11%，43.86% and 14.03%.The difference between the two groups was statistically significant (P＜0.05).The concordance rate of artificial intelligence femoral side measurement in 0，±1，±2 model was 77.19%，19.30%，3.51%.The coincidence rate of traditional template was 54.39%，36.84% and 8.77%.The difference between the two groups was statistically significant (P＜0.05).The prediction of acetabular cup model by artificial intelligence 3D programming system was highly correlated with the actual model(r＝0.886，P＜0.05)，and  a high correlation between prediction of femur prosthesis size and actual application type (r＝0.874，P＜0.05).There was no significant correlation between BMI and the accuracy of artificial intelligence measurement of mortar cup and femoral stem prosthesis (P＞0.05).And no significant correlation between the lower limb length difference and the accuracy of artificial intelligence measurement of socket and femoral stem prosthesis (P＞0.05).Conclusion Artificial intelligence three-dimensional planning has a better predictive effect on the selection of prosthesis size in total hip arthroplasty than film template measurement.There is no significant correlation between BMI and lower limb length difference and measurement accuracy.

Objective To investigate the correlation between serum bone alkaline phosphatase (BALP) level and bone volume in elderly patients with osteoporosis (OP).
Methods 73 elderly patients with OP from the People’s Hospital of Xinjiang Uygur Autonomous Region from June 2019 to June 2020 were selected，and the baseline data of patients were investigated and recorded.There were 22 males and 51 females aged 63 to 82 years，with an average age of (71.25±4.31) years.The serum markers of bone metabolism，including blood calcium，blood phosphorus，BALP and bonegla protein (BGP) of patients were detected.Bone volume and bone mineral density were measured by imaging examination.All patients were treated with calcium and/or vitamin D for 24 weeks，the changes of serum markers of bone metabolism，bone volume and bone mineral density were compared before and 24 weeks after treatment.The correlation of bone metabolism with bone volume and bone mineral density was analyzed.The bone volume of patients with different data was compared，and the correlation between BALP and bone volume was mainly analyzed.Results There was no statistical significant difference in the comparison of serum calcium and phosphorus levels before and 24 weeks after treatment (P＞0.05).After 24 weeks of treatment，the serum BALP level was lower than that before treatment，and the serum BGP level，bone volume and bone mineral density were higher than those before treatment.There was a statistical significant difference (P＜0.05)；Pearson correlation analysis showed that blood calcium and serum BALP levels were negatively correlated with bone volume and bone mineral density (r＝－0.294、－0.776，P＜0.05)，blood phosphorus and serum BGP levels were positively correlated with bone volume and bone mineral density (r＝0.322、0.640，P＜0.05).There was no statistical significant difference in the comparison of bone volume between patients with different gender，age，blood calcium and phosphorus (P＞0.05).The bone volume of patients with high serum BALP level was less than that of patients with normal serum BALP level，and the bone volume of patients with low serum BGP level was less than that of patients with normal serum BGP level.There was a statistical significant difference (P＜0.05).By multiple linear regression analysis，the results showed that the abnormal expression of serum BALP and BGP might be related to the bone volume of OP patients，the overexpression of BALP and low expression of BGP might be the influencing factors of bone volume reduction in OP patients (P＜0.05).
Conclusion The bone volume and bone mineral density of elderly OP patients can be improved by treatment，and the poor improvement of bone volume and bone mineral density may be related to the overexpression of BALP.The overexpression of BALP is negatively correlated with bone volume.With the increase of serum BALP，the bone volume is decreased.

Objective To investigate the effect of mmu-miR-27a-5p on macrophage polarization at the site of spinal cord injury and the recovery of hindlimb motor function after spinal cord injury in mice.Methods A total of 160 mice were randomly divided into sham (group A)，model (group B)，mmu-miR-27a-5p-mimic (group C)，mmu-miR-27a-5p-negative control (group D).On day 3 after successful establishment of spinal cord injury model，Group A received no treatment.Group B，C，D were injected with 10μL of saline，mmu-miR-27a-5p-mimic suspension and mmu-miR-27a-5p-negative control suspension into the injured site，respectively.The behavioral changes，macrophage polarization and glial scar were observed.Results The behavioral scores in group C were higher in each treatment than in group B and D (P＜0.01).HE staining of the spinal cord glial scar showed that spinal cord tissue was normal in group A at each time point.In group C，the bleeding was more obvious 1 day after spinal cord injury，while the inflammatory cells gathered，which was lighter than that in group B at 7 days and 14 days after spinal cord injury.In the D group，the staining was not different from that in group B.Immunohistochemical staining showed that there was no significant change in the morphology of tan cells in group A，but the number of tan cells in group C was obviously lower than that in group B and group D，and the differences were statistically significant (P＜0.01).The expression of GFAP in group B and group D were significantly higher than those in group C，and the differences had a statistical significance(P＜0.01).The expression of GFAP in group A was normal.The result of Western Blot showed that there was no statistical significance in the expression of IL-1β、TNF-α，IL-10，and Arginase-1 in group A at each time point(P=0.96).The expression of IL-1β and TNF-Α in group C was lower than that in group B and group D at 7 days and 14 days after the operation，while the expression of IL-10 and Arginase-1 was higher，the differences had a statistical significance (P＜0.01).Flow cytometry showed that the CD16 marks in group and group D were obviously higher than that in group C at 7 days and 14 days after the operation，and the differences were statistically significant(P=0.000).The marks of Arginase-1 in group C were significantly higher than those in group B and group C at 7 days and 14 days after the operation(P=0.000).Conclusion Injection of mmu-miR-27a-5p can promote the polarization of macrophages toward the M2 phenotype at the site of spinal cord injury，and improve the recovery of hindlimb motor function within 14 days after spinal cord injury in mice.