[Effect of behavioral intervention based on social media to promote HIV/syphilis testing in young men who have sex with men].

Objective: To evaluate the effect of social media based behavioral intervention on promoting joint testing of HIV and syphilis in young men who have sex with men (MSM). Methods: After the recruitment, the participants who met the inclusion criteria were randomly divided (1∶1) into two groups, i.e. social media intervention group and control group. The control group was given routine voluntary counseling and testing (VCT) services. The intervention group was also given VCT services, besides; the comprehensive strategies through social media, including regular health education message and testing information sending, were given to them to strengthen the behavioral intervention. Follow up was conducted for the participants for 12 months after the intervention. The number and the proportion of young MSM receiving HIV and syphilis testing, and the reported proportion of the young MSM with sexually transmitted diseases (STD) symptoms between the intervention group and the control group were compared to evaluate the effect of the intervention. Results: A total of 315 young MSM were recruited (158 in the intervention group and 157 in the control group), in whom 248 young MSM completed the follow up. The follow-up rate was 78.7%. There was no significant difference in baseline characteristics between the intervention group and the control group (all P>0.05). The proportion of young MSM receiving more than one joint testing in the intervention group was slightly higher than that in the control group (53.2% vs. 48.4%, rate difference (RD): 4.8%, 95%CI: -7.5%-17.0%, P=0.448) without significant difference. However, in the young MSM who used condoms in the last anal sex, the proportion of those receiving more than one joint testing in the intervention group was higher than that in the control group (63.8% vs. 46.1%, RD: 17.7%, 95%CI: 1.5%-32.6%, P=0.035). In addition, the reported proportion of young MSM with STD symptoms in the intervention group was significantly lower than that in the control group (6.3% vs. 18.0%,RD: -11.7%, 95%CI: -20.6%- -3.0%, P=0.005). Conclusion: Compared with routine VCT, social media based behavioral intervention might promote joint HIV and syphilis testing in the young MSM who used condom in the study. It could significantly reduce the reporting proportion of STD symptoms, suggesting that this method can promote the AIDS and STD prevention related behaviors in young MSM.

[Conducting implementation research of HIV self-testing for overall achievement of HIV/AIDS prevention and treatment goal in China].

The current situation of AIDS prevention and control is still challenging in China. Although China has made great progress in expanding HIV testing and promoting case identification, there are still a large number of HIV-infected individuals who have not been identified, which might influence the overall achievement of the goal of HIV/AIDS prevention and control. Thus, China needs to further promote self-testing while conducting routine HIV testing and use it as a supplement to further expand HIV testing coverage. The articles in this issue focus on the global situation of HIV self-testing services, reports the changes of self-testing among MSM in China from 2013 to 2018, and compares the effects of different HIV/syphilis self-testing models in promoting HIV/syphilis testing in key populations in order to achieve the overall goal of AIDS prevention and control in China.

[Current status of HIV self-testing application].

HIV self-testing is a key measure and strategy to expand the coverage of HIV testing in key populations, which has great value in application and high acceptance in key populations. The World Health Organization (WHO) issued the Guidelines on HIV self-testing and partner notification in 2016 to support the application of HIV self-testing and provide specific guidance for countries and organizations to develop corresponding public health policies for the purpose of improving the accessibility and utilization of HIV diagnostics. HIV self-testing has been promoted in many countries and has achieved great results. This article provides an overview of the current domestic and international HIV self-testing policies, intervention models, the use of self-testing kits, the accuracy of self-testing kits, and the application of pre- and post-testing counseling services to provide reference for the further improvement of HIV self-testing in China.

[The roles of two HIV self-testing models in promoting HIV-testing among men who have sex with men].

Objective: To evaluate the roles between two different HIV self-testing models in promoting HIV-testing among men who have sex with men (MSM). Methods: This paper focuses on two HIV self-testing service models. The first; is the online self-testing model (HIV self-testing conventional model) with the sexual health promotion network platform. The other one is an innovative HIV self-testing model (secondary distribution model), based on the previous program. The two different self-testing models, including the number of indexes and alters, the positive rate, and the demographics of indexes and alters, are compared. The influence of volunteers with or without leadership on the number of HIV self-test kits distributed or self-use is analyzed through the leadership survey scale. Results: The return rates of HIV self-testing results in the two models are 94.7%(323/341) and 99.2%(1 141/1 150), respectively, within 30 days. The proportion of alters in the secondary distribution is significantly higher (45.9%,281/612) than the conventional HIV self-testing (6.3%,20/318). In the secondary distribution model, the difference between the number of indexes and alters indicators including age, marital status, residence, sex orientation, anal sex with men in the past six months, and HIV test are statistically significant (χ2 test, all P<0.05). The opinion leader of MSM has significantly impacted the promotion of HIV self-testing (P<0.05). Conclusions: Both models can promote HIV self-testing, result return, and HIV positive detection among MSM. In terms of expanding the testing and detection of HIV positive, the secondary distribution mode shows more obvious advantages, which significantly promotes a large number of MSM who have never been tested for HIV to undergo HIV testing. Influential indexes have a significant effect on increasing the HIV testing rate and promoting HIV testing among MSM.

[Changing trends of HIV testing and HIV self-testing in men who have sex with men on a gay social networking app].

Objective: To understand the changing trends of HIV testing rates, with a focus on HIV self-testing, and to evaluate the impact of HIV self-testing on expanding HIV testing among MSM in China in past few years. Methods: MSM were recruited online nationwide via a gay social networking app (Blued) from 2013 to 2016 and 2018. The survey collected information about socio-demographic backgrounds, sexual behaviors, and prior HIV testing experiences, including HIV self-testing. Trend analyses were conducted. Results: Respectively, 1 342, 1 424, 1 173, 2 105 and 699 MSM were recruited nationwide from 2013 to 2016, and in 2018. The mean age was (30.6±6.6)years in 2013 and showed a decreasing trend afterwards. The HIV testing rate was 60.0% (805/1 342) in 2013 and there was a rising trend from 2013 to 2016, and 2018 (trend Z =19.3, P <0.001), reaching a peak at 77.3% (540/699) in 2018. Further, the HIV self-testing rate increased from 19.3% (259/1 342) in 2013 to 58.1% (406/699) in 2018 (χ2=237.5, P <0.001). The proportion of MSM who had HIV self-testing among prior HIV testers significantly increased from 32.2% (259/805) to 75.2% (406/540) during the study period (trend Z =14.3, P <0.001). Conclusions: The HIV testing rate, HIV self-testing rate and proportion of men who had HIV self-testing among former HIV testers among web-based Chinese MSM showed substantial increases from 2013 to 2016,and 2018. This suggests that HIV self-testing may have a significant effect on the expansion of HIV testing coverage in MSM, and has important public health implications for HIV/AIDS prevention in China.

[Evaluating the effectiveness of HIV/syphilis joint self-testing in promoting syphilis testing among men who have sex with men].

Objective: To evaluate the effectiveness of HIV/syphilis joint self-testing in promoting syphilis testing among men who have sex with men (MSM). Methods: In July 2019, the research participants were recruited through the Danlan website (https://www.danlan.org). Participants who met the selection criteria, and were randomly assigned into one of the three study groups (1∶1∶1) including HIV/syphilis joint self-testing group and lottery incentive self-testing group and control group. Self-test reagents were mailed to HIV/syphilis joint self-testing group and lottery incentive self-testing group, and the subjects in control group were encouraged to go to offline locations for testing. One month later, follow-up was conducted to evaluate the differences in the testing rates of syphilis among the three groups. Results: A total of 145 subjects were included in this study, including 48 in control group, 49 in HIV/syphilis joint self-testing group and 48 in lottery incentive self-testing group. During the follow-up period, the self-testing rate of syphilis was 74.4% (32/43) in HIV/syphilis joint self-testing group, 70.0% (28/40) in lottery incentive self-testing group and 36.4% (16/44) in control group. Multivariate logistic analysis revealed that the proportions of syphilis testing in HIV/syphilis joint self-testing group and lottery incentive self-testing group were 5.38 (95%CI: 2.06-14.04) times and 4.54 (95% CI: 1.75-11.74) times higher than that in control group during the follow-up period. Conclusions: HIV/syphilis joint self-testing and lottery-incentives-prompted self-testing significantly increased the testing rate of syphilis in MSM, respectively. HIV/syphilis joint self-testing is feasible for promotion.

[Cost-effectiveness of HIV self-testing strategy in men who have sex with men].

Objective: To analyze the cost-effectiveness and willingness-to-pay of HIV self-testing (HIVST) strategy and facility-based HIV rapid testing (HIV-RDT) strategy in men who have sex with men (MSM) in Zhuhai, and provide scientific evidence for making health policy. Methods: From the perspective of health service providers, the data of the costs and effectiveness of two HIV testing strategies in MSM in Zhuhai during January-September 2019 were collected, and a decision-tree model of cohort of 10 000 MSM was constructed by using software TreeAge Pro 2019 to measure the cost-effectiveness ratio (CER) and the incremental cost-effectiveness ratio (ICER). One-way and probability sensitivity analysis was performed for the uncertainty of the parameters in the model, and the cost-effectiveness and affordability curve was introduced to estimate the affordability of two strategies. Results: After the mobilization of MSM community-based organization through Internet and social media, 2 303 MSM had HIVST, in whom 33 were HIV positive (1.7%), and 816 MSM received HIV-RDT, in whom 35 were HIV positive (4.3%). The cost for per screening was 60.45 yuan and 240.43 yuan (RMB) respectively, and the cost for per positive screening was 4 218 yuan and 5 606 yuan (RMB) rerspectively. The results of the decision-tree model showed that the mean cost for a MSM using HIVST and using HIV-RDT was 44.67 yuan and 148.42 yuan (RMB) respectively, and the ICER was negative. HIVST strategy was a more cost-effective option when the willing-to-pay was below 6 528 yuan (RMB) for per positive screening, and HIV-RDT strategy was a more cost-effective option when the investment was higher than 6 528 yuan (RMB). Conclusion: HIVST strategy in Zhuhai is a public health project with economic value, and policy makers should strengthen the support to MSM community-based organization to promote the application of HIVST among MSM.

[Status quo and characteristic analysis among MSM-users of the "Internet Plus-based AIDS Comprehensive Prevention Service System" in Guangzhou].

Objective: To analyze the characteristics of the "Interner Plus-based AIDS Comprehensive Prevention Service System" among MSM who frequently using the Internet in Guangzhou. Methods: An online survey was conducted among MSM who were recruited through gay-website portals between August and September, 2018 in Guangzhou, to collect information regarding the use of and attitudes on the "Interner Plus-based AIDS Comprehensive Prevention Service System" . Logistic regression was used to explore the association between the use of Internet intervention tools and related behavioral characteristics. Information on the awareness of AIDS, HIV testing, and condomless anal sex behavior were compared between the core or non-core services users. Results: A total of 777 Internet-based MSM were recruited as participants including 638 men (82.1%) as core service users. MSM were satisfied in using the the "Interner Plus-based AIDS Comprehensive Prevention Service System" while more than 80.0% of the users felt that the tools were helpful in: increasing the HIV awareness, promoting test uptake, and reducing those related risk behavior. Comparing with those who did not use the tools, the users showed higher rates in practising condomless anal intercourse (1.50-1.86 times), commercial sex with men (11.60-21.21 times), and unprotected vaginal intercourse (13.62-20.67 times), in the last 6 months. Proportions of core service users appeared as: [96.6% vs. 74.8%, aOR (95%CI): 8.80 (4.85-15.97)] on HIV testing, [56.4% vs. 22.3%, aOR (95%CI): 4.54 (2.94-7.02)] on regular HIV testing and [86.2% vs. 80.6%, aOR (95%CI): 1.75 (1.06-2.89)] on awareness of HIV knowledge respectively, which were all significantly higher than the non-core service users. Conclusions: The frequent Internet using MSM in Guangzhou claimed to have had high acceptance and satisfaction on the local Internet HIV intervention service tools. The "Internet Plus-based AIDS Comprehensive Prevention Service System" had effectively reached the high-risk subgroups of MSM, increasing the awareness on related risk and promoting testing on HIV.

Electrochemical characteristics of amorphous silicon carbide film as a lithium-ion battery anode.

The electrochemical reactions of SiC film with Li+ have been investigated by electrochemical characterization and X-ray photoelectron spectroscopy. The SiC film is prepared by inductively-coupled-plasma chemical-vapor-deposition (ICP-CVD) technique and displays an amorphous state due to the low processing temperature (∼350 °C). An irreversible reaction of SiC with Li+ occurs with the formation of lithium silicon carbide (Li x Si y C) and elemental Si, followed by a reversible alloying/dealloying reaction of the elemental Si with Li+. The 500 nm SiC film shows an initial reversible specific capacity of 917 mA h g-1 with a capacity retention of 41.0% after 100 cycles at 0.3C charge/discharge current, and displays much better capacity retention than the Si film (5.2%). It is found that decreasing the SiC thickness effectively improves the specific capacity by enhancing the reaction kinetics but also degrades the capacity retention (for 250 nm SiC, its initial capacity is 1427 mA h g-1 with a capacity retention of 25.7% after 100 cycles). The better capacity retention of the 500 nm SiC anode is mainly because residual SiC exists in the film due to its incomplete reaction caused by its lower reaction kinetics, and it has high hardness and can act as a buffer matrix to alleviate the anode volume change, thus improving the mechanical stability and capacity retention of the SiC anode.

MiR-646 inhibited cell proliferation and EMT-induced metastasis by targeting FOXK1 in gastric cancer.

BACKGROUND: MiR-646 has been reported to be aberrantly expressed in human cancers. However, the underlying molecular mechanisms of action of miR-646 in gastric cancer (GC) have not yet been investigated. METHODS: In vitro function of miR-646 in GC was evaluated using EdU assay, plate colony formation assay, and matrigel invasion assay. Real-time PCR or western blotting was performed to detect miR-646 and FOXK1 expressions. In vivo tumour growth and metastasis were conducted in nude mice. RESULTS: MiR-646 expression was downregulated in GC tissues compared with adjacent normal tissues. Low miR-646 expression is associated with malignant progression. Transient transfection of GC cells with miR-646 inhibited their growth and migration. Moreover, miR-646 influenced the expression of epithelial-mesenchymal transition (EMT)-associated proteins. TGF-ß1 treatment significantly suppressed the expression of miR-646 and overexpression of this microRNA counteracted the influence of the TGF-ß1-induced EMT phenotype. In terms of the underlying mechanism, miR-646 directly targeted FOXK1. In vivo, it inhibited the FOXK1-mediated proliferation and EMT-induced metastasis. Consistently, inverse correlations were also observed between the expression of miR-646 and FOXK1 in human GC tissue samples. Furthermore, miR-646 regulated Akt/mTOR signalling after FOXK1. CONCLUSIONS: miR-646 inhibited GC cell proliferation and the EMT progression in GC cells by targeting FOXK1.

Synthetic diagnostics platform for fusion plasmas (invited).

A Synthetic Diagnostics Platform (SDP) for fusion plasmas has been developed which provides state of the art synthetic reflectometry, beam emission spectroscopy, and Electron Cyclotron Emission (ECE) diagnostics. Interfaces to the plasma simulation codes GTC, XGC-1, GTS, and M3D-C1 are provided, enabling detailed validation of these codes. In this paper, we give an overview of SDP's capabilities, and introduce the synthetic diagnostic modules. A recently developed synthetic ECE Imaging module which self-consistently includes refraction, diffraction, emission, and absorption effects is discussed in detail. Its capabilities are demonstrated on two model plasmas. The importance of synthetic diagnostics in validation is shown by applying the SDP to M3D-C1 output and comparing it with measurements from an edge harmonic oscillation mode on DIII-D.

Outcome of adult critically ill patients mechanically ventilated on general medical wards.

OBJECTIVE. A significant number of critically ill mechanically ventilated patients are not admitted to the Intensive Care Unit but are cared for on general wards. This study looked at the outcome of these patients. DESIGN. Case series. SETTING. A 1100-bed tertiary hospital in Hong Kong. PATIENTS. All adult patients admitted in a 2.5-year period who received invasive mechanical ventilation on general medical wards without admission to Intensive Care Unit or other special care areas. INTERVENTIONS. Invasive mechanical ventilation. MAIN OUTCOME MEASURES. The observed number of deaths, the expected number of deaths as derived from the Mortality Probability Model II system admission model, and other morbidity measures. RESULTS. Among 755 patients studied, the observed number of deaths was 673, which amounts to a mortality of 89.1%. The expected number of deaths was 570. The risk-standardised mortality ratio was 1.18 (95% confidence interval, 1.09-1.28; P<0.0005). Patients with chronic obstructive pulmonary disease had the lowest mortality rate of 70.8% (P<0.005). The post-cardiac arrest subgroup had the highest mortality of 99.0%. CONCLUSIONS. There was a worse-than-predicted survival in the absence of Intensive Care Unit care for the critically ill patients who received mechanical ventilation on general wards. Patients with chronic obstructive pulmonary disease warranted more Intensive Care Unit admissions. Early discontinuation of invasive support should be seriously considered in the post-cardiac arrest patients.

Mechanical properties and in vitro response of strontium-containing hydroxyapatite/polyetheretherketone composites.

Strontium-containing hydroxyapatite/polyetheretherketone (Sr-HA/PEEK) composites were developed as alternative materials for load-bearing orthopaedic applications. The amount of strontium-containing hydroxyapatite (Sr-HA) incorporated into polyetheretherketone (PEEK) polymer matrix ranged from 15 to 30 vol% and the composites were successfully fabricated by compression molding technique. This study presents the mechanical properties and in vitro human osteoblast-like cell (MG-63) response of the composite material developed. The bending modulus and strength of Sr-HA/PEEK composites were tailored to mimic human cortical bone. PEEK reinforced with 25 and 30 vol% Sr-HA exhibited bending modulus of 9.6 and 10.6 GPa, respectively; alternatively, the bending strengths of the composites were 93.8 and 89.1 MPa, respectively. Based on the qualitative comparison of apatite formation in SBF and quantitative measurement of MG-63-mediated mineralization in vitro, the Sr-HA/PEEK composite was proven to outperform HA/PEEK in providing bioactivity. However, no difference was found in the trend of cell proliferation and alkaline phosphatase activity between different composites. Strontium, in the form of strontium-containing hydroxyapatite (Sr-HA), was confirmed to enhance bioactivity in the PEEK composites.

Value of a single preoperative PFA-100 measurement in assessing the risk of bleeding in patients taking cyclooxygenase inhibitors and undergoing total knee replacement.

BACKGROUND: The usefulness of the PFA-100 in assessing the risk of bleeding in non-cardiac surgery is not clear. This study aims to examine this by correlating preoperative PFA-100 measurement with perioperative bleeding in patients receiving cyclooxygenase (COX) inhibitors. METHODS: PFA-100 with adenosine-5'-diphosphate (ADPCT) and epinephrine (EPICT) cartridges were measured before operation in consecutive patients undergoing elective total knee replacement and taking different COX inhibitors. Surgery and anaesthesia were performed by the same team using standardized techniques. Intraoperative blood loss and postoperative drain output were recorded by anaesthetists and nurses blinded to the PFA-100 measurements. Surgeons, similarly blinded, were asked to rate the quality of haemostasis. Correlation was sought between these data and PFA-100 measurements. RESULTS: Thirty patients were studied, involving 51 knees. Preoperative PFA-100 EPICT was correlated with drain output (r=0.30, P=0.03). The correlation becomes stronger when a 20% in vitro haemodiluted sample was used for measurement (r=0.42, P=0.01). Receiver-operating characteristic curve analysis using the diluted measurements [area under curve (AUC) 0.74 (95% CI 0.54-0.94)] suggested using a cut-off value of 188 s for EPICT, which will predict excessive drain output with 89% sensitivity, 54% specificity, and a likelihood ratio of 1.93. Diluted EPICT was also correlated with surgeon rating of haemostasis (r=0.36, P=0.04) although none of the measurements correlated with intraoperative blood loss. CONCLUSIONS: Preoperative PFA-100 prolongation is correlated with increased postoperative drain output. It can be a potentially useful preoperative measurement in patients taking COX inhibitors.

Gyrokinetic studies on turbulence-driven and neoclassical nondiffusive toroidal-momentum transport and the effect of residual fluctuations in strong E x B shear.

A significant inward flux of toroidal momentum is found in global gyrokinetic simulations of ion temperature gradient turbulence, leading to core plasma rotation spin-up. The underlying mechanism is identified to be the generation of residual stress due to the k parallel symmetry breaking induced by global quasistationary zonal flow shear. Simulations also show a significant off-diagonal element associated with the ion temperature gradient in the neoclassical momentum flux, while the overall neoclassical flux is small. In addition, the residual turbulence found in the presence of strong E x B flow shear may account for neoclassical-level ion heat and anomalous momentum transport widely observed in experiments.

A review of necrotising fasciitis in the extremities.

OBJECTIVE: To review currently available evidence on the epidemiology and methods of management for necrotising fasciitis, with particular reference to Hong Kong. DATA SOURCES AND STUDY SELECTION: Medline, PubMed, and Cochrane Library searches of local and internationally published English language journals, from 1990 to July 2008 using the terms 'necrotising fasciitis', 'Hong Kong', 'diagnosis', 'epidemiology', 'vibrio', 'streptococci', 'clostridia', and 'management'. DATA EXTRACTION: All articles involving necrotising fasciitis in Hong Kong were included in the review. DATA SYNTHESIS: The incidence of necrotising fasciitis in Hong Kong and around the world has been increasing. This rapidly progressive infection is a major cause of concern, due to its high morbidity and mortality. Up to 93% of affected patients at our hospital were admitted to the Intensive Care Unit and many still died from septic complications, such as pneumonia and multi-organ failure. Radical debridements in the form of amputations and disarticulations were considered vital in 46% of the patients. Early recognition and treatment remain the most important factors influencing survival. Yet, early diagnosis of the condition is difficult due to its similarities with many other soft tissue disorders such as cellulitis. Repeated surgical debridement or incisional drainage continues to be essential for the survival of sufferers from necrotising fasciitis. Many authorities have reported that carrying out the first fasciotomy and radical debridement within 24 hours of symptom onset was associated with significantly improved survival, which also emphasises the importance of early diagnosis. CONCLUSION: Clinicians must adopt a high index of suspicion for necrotising fasciitis. Empirical antibiotics must be started early and repeated physical examinations should be performed, while maintaining a low threshold for tissue biopsy and surgery. The timing of the first fasciotomy and radical debridement within a window of 24 hours from symptom onset is associated with significantly improved survival.

Computer navigation did not improve alignment in a lower-volume total knee practice.

UNLABELLED: Postoperative alignment of the implanted prosthesis in computer-navigated TKA has been reported to be superior to that using the conventional technique. There is an assumption that use of computer navigation techniques can make an inexperienced or occasional TKA surgeon perform more like an expert TKA surgeon. To assess improved accuracy in recreation of mechanical alignment in TKA performed using computer navigation, a retrospective review of the experience of one of the authors (WPY) before and after using computer navigation was performed. We reviewed the radiographic results of 104 TKAs (52 computer navigation, 52 conventional technique) and found the accuracy of postoperative radiographic alignment of the implanted prosthesis was not improved by using computer navigation as judged by (1) overall limb alignment (case: varus 1.3 degrees ; control: varus 0.3 degrees ); (2) femoral component alignment (case: 90.3 degrees ; control: 90.3 degrees ); and (3) tibial component alignment (case: 89 degrees ; control: 90 degrees ). Significant factors that affected postoperative overall mechanical alignment in the current navigation series included severity of the preoperative deformity, amount of error in making bone cuts, and experience of the surgeon in using the computer navigation system. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside's line.

PURPOSE: To assess inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside's line in a cadaveric model mimicking total knee arthroplasty. METHODS: Four cadaveric knees with intact soft tissues were used. The knees were exposed anteriorly using the Insall approach, with the patella everted laterally. Three observers (2 surgeons and one trainee) took turns to identify the anatomic landmarks of the transepicondylar axis and Whiteside's line. Each observer repeated the process 20 times. Each identification was photographed and referenced with the true values obtained from the knees after they were stripped of all soft tissue. Inter- and intra-observer errors in the anatomic landmarks were compared. RESULTS: Inter-observer error was significant with both the transepicondylar axis and Whiteside's line (p<0.001, one-way ANOVA). The intra-observer variation was greater for Whiteside's line than the transepicondylar axis (standard deviation, 4.2 vs 2.5 degrees). The maximum potential errors in the transepicondylar axis and Whiteside's line were 13 degrees and 24 degrees, respectively. CONCLUSION: The accuracy of rotational alignment of the transepicondylar axis and Whiteside's line were operator-dependent, and their intra-operative reproducibility was low.

The accuracy of extramedullary guides for tibial component placement in total knee arthroplasty.

Anteroposterior radiographs that included the whole tibia were taken before and after 75 total knee arthroplasties in 48 patients. The same tibial extra-medullary alignment guide system was used in every knee. The average tibial component alignment was 0.4 (SD 2.5, range -4.9 to 6.4) degrees of valgus post-operatively. 59 tibial components (78.7%) had a tibial cut within 3 degrees from being perpendicular to the mechanical axis, ten were too valgus (13.3%) and six were too varus (8%). The chance of the tibial components becoming too varus was higher if there was lateral tibial bowing, compared with no tibial bowing (p=0.048). A smaller lateral width of the leg increased the chance of the tibial components becoming too valgus (p=0.047).