BACKGROUND:Many studies reported the relationship of the mechanical properties and water content about bone tissue, which is one of organizations containing the lowest water content on human body. Researches on effect of water on biological tribology behavior of bone tissue have been rarely reported and are the experimental study generally. OBJECTIVE:To explore the influence and the damage mechanism of water on biological tribology behavior of bone tissue, by comparing multiscale numerical model established with the experiment. METHODS:Dehydration of the bone tissue was studied by nanoindentation test and both reciprocating sliding and impact wear tests. A multi-scale finite element model was constructed under a flat-on-ball configuration. RESULTS AND CONCLUSION:The viscoelasticity and the tribological properties of bone tissue significantly decreased as well as the different wear mechanisms under applied loading after drying. The analytical results indicated that there were high stress condition, which incurred the micro-crack initiation and the appearance of peeling and wear, around the Haversian canal, circumferential lamellas and the interstitial tissues. Meso-scale:dehydration weakened the function of absorption and interruption of stress, which facilitated crack extension in pore. Micro-scale:the high stress gradient of structure of canaliculi and lacunae is an important cause of tissue damage.

Objective To compare the prescrotal orchiopexy and traditional inguinal orchiopexy in the clinical treatment of children with low cryptorchidism.Methods Seventy-two patients(78 testes)who underwent orchiopexy in our hospital during March 2006 to May 2011 were retrospectively analyzed.And the undescended testis could be manipulated beyond the external inguinal ring under anaesthesia.Matching conditions were age differences among 3 months,same preoperative testicular positioning,same surgeon and same side.Using the paired study of 1 to 1,all the patients were divided into 2 groups: prescrotal orchiopexy(group A)and the traditional inguinal orchiopexy(group B),each group included 36 patients(39testes).Mean age was 5.4 years(group A)and 5.5 years(group B).The time of operation and restore standing,success rate and complications,including hernia,hydrocele,testicular atrophy and ascent were compared between the 2 groups.Results All the patients were successfully operated.The average surgical time for the prescrotal and inguinal groups were 33 and 41 min(P =0.0022),and average time of standing was 1.2 and 5.4 d(P =0.0003).All the patients had no wound infection.Followup ranged from 3 to 65 months.No hernia,hydrocele,testicular atrophy and ascent were identified in either group.The ratios of successful surgery were 100％ in the two groups.Conclusions The prescrotal orchiopexy is simple,safe,and effective in the cases that testis could be pushed down through the external inguinal ring.Compared with traditional inguinal approach,the advantages of prescrotal approach are shorter operative time,fewer traumas,less pain,faster recovery and cosmetic results.

Objective To investigate the effect of atorvastatin on blood lipid and carotid atherosclerosis in patients with hyperlipidemia and cerebral infarction.Methods 98 patients with hyperlipidemia and cerebral in-farction in our hospital from September 2014 to February 2017 were selected and divided into observation group(49 cases)and control group(49 cases)according to the random number table method.The control group was treated with conventional treatment,the observation group was treated with atorvastatin on the ba-sis of the control group.The two groups were treated for 4 weeks.The ADL score,NIHSS score,blood lipid index,carotid IM T and carotid plaque area were compared between the two groups before and after treatment. Results ADL score of the patients in the observation group after treatment higher was than the control group (t=12.7783,P<0.05),NIHSS score was lower than the control group(t=10.941,P<0.05);LDL-C,TC and TG levels after treatment in the observation group were than in the control group(t= 17.239,9.216, 9.800,P<0.05),while the HDL-C level was higher than the control group(t=7.683.P<0.05);the patients in the observation group were treated by carotid artery IM T and carotid plaque area was higher than that of the control group(t=8.919,6.344,P<0.05).Conclusion Atorvastatin can improve hyperlipidemia in pa-tients with cerebral infarction and carotid atherosclerosis,dyslipidemia,has the important research signifi-cance.

Objective 聽 聽To evaluate the mid-term outcomes between tricuspid valve detachment (TVD) and non-detachment (NTVD) for ventricular septal defect (VSD). Methods 聽 聽 The patients who underwent perimembranous VSD repair in the Department of Cardiovascular Surgery, West China Hospital from 2015 to 2020 were included. According to the surgical method, the patients were divided into a TVD group and a NTVD group. The clinical data of the two groups were compared. Results 聽 聽 Totally 538 patients were included in the study. There were 240 patients in the TVD group, including 121 males and 119 females, with an average age of 3.85卤8.42 years and an average weight of 14.12卤12.97 kg. There were 298 patients in the NTVD group, including 149 males and 149 females, with an average age of 4.42卤9.36 years and an average weight of 14.87卤12.51 kg. There was no statistical difference in the age, weight, sex, preoperative New York Heart Association (NYHA) classification or tricuspid regurgitation (TR) degree between the two groups (P>0.05). Median follow-up was 30 (23, 40) months in the TVD group, and 29 (23, 41) months in the NTVD group (P=0.600). After operation, one patient in each group developed third-degree atrioventricular block and recovered to sinus rhythm before discharge (P=0.848). No pacemaker was needed. There was no statistical difference in the length of stay (P=0.054), mortality (P=1.000), in-hospital reoperation (P=0.199), or follow-up reoperation (P=0.505). More than 98% of patients in both groups had postoperative TR less than moderate (P=0.926). At the last follow-up, only 7 (2.9%) patients in the TVD group were detected trivial residual shunting, and 14 (4.7%) in the NTVD group (P=0.289). No one needed to have reoperation because of residual VSD. The TVD group showed less TR during the follow-up (P=0.019). Conclusion     TVD is an alternative technique which can be safely used in the closure of VSD, especially in technologically mature medical center. Appropriate tricuspid valve detachment for those hard-to-expose VSDs does not result in poorer tricuspid valve function or higher risk of atrioventricular block, and might reduce the incidence of residual shunting.

Hypertrophic obstructive cardiomyopathy (HOCM) is a relatively common hereditary cardiomyopathy, which is featured by asymmetric myocardial hypertrophy and dynamic left ventricular outflow tract (LVOT) obstruction. Other than septal hypertrophy, mitral valve abnormalities are also quite common in HOCM patients, and they also contribute to systolic anterior motion of the mitral leaflets and LVOT obstruction. Septal myectomy is believed as the standard surgical treatment for HOCM, but whether to perform mitral valve procedures at the same time of myectomy is still debatable. In this article, we thoroughly explained the mitral valve abnormalities in HOCM patients and their surgical corrections. Besides, we also explained the controversies over mitral valve procedures based on the current clinical studies.