Femoral head necrosis and nonunion is a common complication after surgery of femoral neck fracture.Recently,femoral neck shortening have caused attentions which can impact the function of hip.Incidence,mearsurement,influence factor,prevention and treatment of femoral neck shortening have been retrospective reviewed.Amount of femoral neck shortening with sliding compression system is significantly more than length of stability system,which is result from its own mechanism.However,effcacy of length of stability system still need a large scale of sample.It uses radiography to diagnose shortening.The present measurement methods include displacement of femoral head,xyz-axis measurement,the length of exposed screw,the collapse of femoral head.However,position,the angle of screen and the defect of the method would increase deviation.A measurement with simple,wide application and accuracy need to continue to explore.Apart from patients' condition,shortening also affected by the pattern and quality of surgery.Overall,older women,displacement fracture,unsatisfactory reduction will increase the risk and shrinkage of shortening.In addition,the pattern of the internal fixation becomes the research focus in the field of orthopedic clinical research.Including the transformation of sliding compression system device and design of novel device.How to combine them together organically could be a future development direction.Meanwhile,there are still in exploratory stage to decide whether biological combined with internal fixation can prevent shortening.Intertrochanteric osteotomy can achieve union and correct the limblength discrepancy,However,it did not restore the length of femoral neck.So,it is unknown that whether the method can solve the slight shortening which have impacted the hip function.

Objective: To learn the population,virus status and viral types of hantavirus（HV）hosts in Tiantai County of Zhejiang Province from 2011 to 2018,and to provide evidence for hemorrhagic fever with renal syndrome（HFRS）control. Methods: Rodents in Tiantai County were captured by night trapping method. After the species and age of rodents were identified,the composition of rodent species,dominant species and density of rodents were analyzed. The lungs and blood of rodents were sampled to detect the antigen and antibody of HV by immunofluorescence method. The HV antigen-positive lung samples were detected by RT-PCR with specific primers of HV S fragment,then HV was isolated and identified by inoculating Vero-E6 cells. Results: The average rodent density in Tiantai County from 2011 to 2018 was 4.44%. The rodent density in the field and residential areas were 4.94% and 2.23%,respectively. Ten species of rodents were identified,with Apodemus agrarius dominant in the field and Rattus norvegicus in the residential areas. Sixty-seven lung samples were HV antigen positive（4.13%）,one from Rattus norvegicus and the other sixty-six from Apodemus agrarius. Seventy-nine blood samples were HV antibody positive（4.86%）,all from Apodemus agrarius. Thirty-four HV antigen-positive lung samples were positive（50.75%）after RT-PCR amplification. Twenty-two strains of virus were isolated and all of them were from Apodemus agrarius,including twenty-one strains of Hantaan type（HTN）and one strain of Seoul type（SEO）. Conclusion In Tiantai County,Apodemus agrarius is the main source of HFRS infection;the main epidemic type of HV is HTN and SEO is first found in Apodemus agrarius.

Objective: By investigating the genotype and evolutionary variation of hantavirus (HV) in Tiantai county, a national surveillance site for hemorrhagic fever with renal syndrome (HFRS) was set in Zhejiang province, from 2011 to 2018, to reveal the molecular epidemiological characteristics of hantavirus (HV) in Tiantai. Methods: Total RNA was extracted from ultrasound treated HV antigen- positive rat lung samples in Tiantai from 2011 to 2018. After cDNA was prepared, nested PCR was used to amplify partial sequence of M fragments by using specific primers of HV. The sequences of HV in Tiantai from 2011 to 2018 were compared with other known HV sequences in order to identify the genotype and analyze the evolution and variation of the virus. Results: In 67 HV antigen-positive lung specimens, 31 were positive in nested PCR amplification with type-specific primers, including 30 Hantaan virus (HTNV) positive samples, 1 Seoul virus (SEOV) positive sample, and all the 31 samples were from Apodemus agrarius. The phylogenetic tree based on partial M segment was divided into monophyletic group, 30 strains were distributed in HTNV group and 1 was in SEOV group. The HTNV strain Tiantai T2018-130 was independently in one branch, sharing 84.8%-87.9% homology with other strains both at home and abroad, including 29 strains in HTNV group in Tiantai. The other 29 HTNV strains in Tiantai showed closer relationship. The SEOV strain T2016-31 from Apodemus agrarius showed closer relationship with previous strains of SEOV, Tiantai ZT71, ZT10 and Z37 strains of Wenzhou, Zhejiang province. Conclusions HTNV, the main genotype of HV in Tiantai of Zhejiang province, showed obvious geographic clustering, but the strain T2018-130 was distinct from the others in Tiantai. Meanwhile, by sequence analysis, we confirmed that The SEOV strain T2016-31 existed in in Apodemus agrarius, indicating there was a phenomenon of "spillover" between virus and host in SEOV evolution.