Objective: To discuss the surgical technique of lateral unicondylar knee replacement (UKR) for patients with lateral compartment osteoarthritis and evaluate its recent clinical efficacy. Methods: A retrospective analysis was conducted on 22 cases of lateral compartment osteoarthritis patients receiving lateral UKR at Orthopedic Department, Beijing Chao Yang Hospital, Capital Medical University from January 2016 to January 2019.There were 8 males (8 knees) and 14 females (14 knees), aged 65.7 years(range: 54 to 83 years).All patients completed preoperative imaging examination and excluded extra-articular deformity.Lateral parapelatellar approach was used for the operation and the tibial osteotomy was performed by extramedullary positioning.The residual cartilage of the external condyle was removed by pendulum saw to subchondral bone.Appropriate prosthesis were selected, and the tightness of the gap and the stability of the joints were repeatedly confirmed during the operation.The postoperative complications and the results of physical and imaging examinations were collected.The preoperative and postoperative Oxford knee Score (OKS) and knee society score (KSS) of patients were recorded and compared by paired t test. Results: All patients were followed up for 24.6 months (range: 8 to 40 months).No complications such as incision exudation, skin necrosis and deep venous thrombosis of lower limbs were found after the operation.No cases of prosthesis loosening, excessive wear of pads, dislocation and postoperative infection were found at the last follow-up.The OKS decreased from 46.5±3.1 preoperative to 22.4±3.3 postoperative(t=13.4, P=0.00) and KSS improved from 69.5±8.7 preoperative to 90.2±7.4 postoperative (t=16.9, P=0.00) . Conclusions For the treatment of lateral compartment osteoarthritis, UKR has the advantages of rapid recovery of knee function, less complications and less trauma.The short-term efficacy is satisfactory, but the long-term efficacy remains to be observed.

To explore early prevention and control of coronavirus disease 2019 （COVID-19） outbreak based on system dynamics model analysis. The data of early outbreak of COVID-19 were collected from the World Health Organization，covering countries of the China，United States，United Kingdom，Australia，Serbia and Italy. The susceptible-exposed-infected-recovered （SEIR） model was generalized and then its parameters were optimized. According to the parameters in the basic infection number expression，the sensitivity in the system dynamics model was used to quantitatively analyze the influence of the protection rate，infection rate and average quarantine time on the early spread of the outbreak. Based on the analysis results，targeted prevention and control measures for the early outbreak of COVID-19 were proposed. The generalized SEIR model had a good fit for the early prediction and evaluation of COVID-19 outbreaks in six countries. The spread of COVID-19 was mainly affected by the protection rate，infection rate and average quarantine time. The improvement of the protection rate in the first ays was the most important:the greater the protection rate，the fewer the number of confirmed cases. The infection rate in the first 5 days was the most critical:the smaller the infection rate，the fewer the number of confirmed cases. The average quarantine time in the first 5 days was very important:the shorter the average quarantine time，the fewer the number of confirmed cases. Through the comparison of key parameters of six countries，Australia and China had implemented strict epidemic prevention policies，which had resulted in good epidemic prevention effects. In the early stage of the outbreak，it is necessary to improve the protection rate，shorten the average quarantine time，and implement strict isolation policies to curb the spread of COVID-19.
COVID-19 ; China/epidemiology* ; Disease Outbreaks ; Humans ; Quarantine ; SARS-CoV-2

Objective: To understand the serotypes, genotypes and transmission source of dengue viruses(DENV) isolated in Yunnan from 2013 to 2015. Methods: Viral RNA was extracted from serum samples of dengue fever(DF) cases at the acute stage in Yunnan, then the gene fragments of envelope protein(E) region were amplified by RT-PCR. The homology and phylogenetic analysis was made on the nucleotide and deduced amino acid sequences by bioinformatics softwares including Clustal X, DNAStar and MEGA5. Results: Viral nucleic acid detection and sequencing indicated that 40 E genes of DENV were obtained. The serotypes and genotypes of DENV were revealed by homology and phylogenetic analysis based on E genes of DENV. Fifteen virus strains belonged to DENV serotype 1(DENV-1), of these, 14(11 from Ruili, 1 from Lincang and 2 from Kunming) were genotype I(G-I), 1 from Kunming was G-V. Twenty-two virus strains belonged to DENV serotype 2(DENV-2), of these, 10 from Ruili were G-I and 12 from Xishuangbanna were G-IV. Two virus strains belonged to DENV serotype 3(DENV-3) and G-II. One virus strain belonged to DENV serotype 4(DENV-4) and G-I. All detected DENV genotypes were mainly predominant in Southeast Asia. All the 40 Yunnan DENV strains shared high homology with the DENV strains in Southeast Asia countries. Conclusions Four serotypes and multiple genotypes of DENV had been co-circulating in Yunnan from 2013 to 2015. The DENV transmitted from Southeast Asia countries was the main cause of DF in Yunnan. It is necessary to strengthen the surveillance and management on the imported cases of DF in Yunnan.

Objective: To evaluate clinical treatment efficacy of double-row fixation with bridging suture anchors for chronic, severe patellar tendinopathy. Methods: A retrospective study of 18 patients suffered from severe patellar tendinopathy and underwent surgical treatment during January 2009 and June 2014 at Department of Orthopedic, Beijing Chao Yang Hospital, Capital Medical University was conducted. All patients had received conservative therapy for more than 6 months(range: 6-30 months) but the effect was unsatisfactory. There were 10 males (12 knees) and 8 females (12 knees)with age of 47.2 years(range: 32-63 years). Seven cases on the left and 17 cases on the right. The surgical treatment included a midline incision at patellar tendon, complete debridement, and double-row fixation with bridging suture anchors. Visual analogue scale(VAS), Lysholm score were collected preoperatively and postoperatively, and compared by paired-t test. The postoperative complications was recorded. Results: All patients were followed up for 35.7 months (range:24-64 months) without any dropout.VAS decreased from 7.5±1.6 preoperative to 1.4±1.0 (t=4.45, P=0.00) postoperative, Lysholm score increased from 48.3±5.2 to 89.6±5.4 (t=-4.88,P=0.00).The Lysholm score was excellent in 3 cases and good in 15 cases.No patellar tendon rupture or suture fixation failure was recorded during the follow-up period. Conclusions The effect of double-row fixation with bridging suture anchors is satisfactory with few postoperative complications.It can not only improve clinical symptoms of patients, but also restore knee joint function.