Radial Force Analysis of Polydioxanone Coronary Stent by Finite Element Method

Coronary stent is used to treat stenosis artery by recovering the luminal diameter of artery and maintaining the normal blood flow. The geometry of coronary stent is an important factor for the radial force. In this study,the relation between the radial force of stent and crown angle was discussed. The result showed that there was no particular rule between the radial force of stent and the crown angle. The maximum radial force of stent was obtained when the crown angle was 50. 04° and the minimum radial force was got when the crown angle was 75°.

Comparison of post-urethroplasty complication rates in pediatric cases with hypospadias using Vicryl or polydioxanone sutures

Objective:Hypospadias is a common congenital problem among male newborns.Both rapid absorbable sutures(polyglactin,Vicryl)and delayed absorbable sutures(polydioxanone,PDO)are used in hypospadias repair based on the surgeon's preference.This study was conducted to compare post-urethroplasty complication rates in pediatric patients with hypospadias using Vicryl or PDO sutures.Methods:This is a retrospective study which was designed and performed on 583 children aged 1-7 years old who had undergone hypospadias repair from January 2012 to December 2018.Required data were obtained from the patients'medical records.Results:Overall,post-surgical complications were observed in 60(10.3%)patients comprising urethro-cutaneous fistula(n=39,6.7%),meatal stenosis(n=10,1.7%),urethral stricture(n=7,1.2%),and glans dehiscence(n=4,0.7%).The mean age of the children with complications was 3.0±1.3 years.According to Kaplan-Meier estimate,the interval between surgery and development of complications was significantly shorter in the Vicryl group(p=0.037).Overall,complications were more prevalent in Vicryl suture than PDO suture(15.1%vs.5.3%,p<0.001).Regression model revealed that in comparison to the distal type,proximal hypospadias(odds ratio[OR]:103.9,95%confidence interval[CI]:32.2-334.9,p<0.001)and mid-shaft hypospadias(OR:82.9,95%CI:25.9-264.6,p<0.001)while using Vicryl suture instead of PDO suture(OR:62.4,95%CI:21.2-183.8,p<0.001)increased the odds of developing post-urethroplasty complications.Conclusion:We suggest PDO suture in the repair of hypospadias due to its lower complication rate,especially in cases of proximal and mid-shaft hypospadias which can get more complicated than the distal type.

Evaluation of Relationship between the Geometry of Crown and Radial Force in a Polydioxanone Coronary Stent

Polydioxanone(PDS),one of the bioabsorbable materials for coronary stent,is catching eyes of researchers recently. When designing the geometry of the PDS coronary stent,the length and the height of the crown are quite important. However,rarely literatures have discussed the relationship between the two geometry parameters and the radial force of the bioabsorbable coronary stent. Therefore,a current effective tool of finite element method was applied in the evaluation of the relationship. By simulating 4 groups of models,it was obtained that the radial force of the coronary stent would not definitely increase with the rising value of Lcrownfrom 0. 8 mm to 2. 4mm. Meanwhile,Hcrownand radial force of the coronary stent had no linear relationship with each other.

Biodegradable stent for the treatment of a colonic stricture in Crohn's disease

Biodegradable polydioxanone stents were developed for the treatment of refractory benign esophageal strictures but have been suggested as a new therapeutic option for intestinal strictures.The primary advantage of biodegradable stents over self-expandable metallic stents is that removal is not required.There are,however,few data available on their use in the small or large bowel.We herein describe the case of a 33-yearold patient with long-standing Crohn's disease(CD) who developed a fibrotic stricture of the sigmoid too long to be amenable to balloon dilation.The use of a biodegradable polydioxanone stent was chosen to avoid surgery.Combined endoscopic and fluoroscopic placement of the stent was technically simple,safe and clinically successful,and no recurrence of obstructive symptoms occurred during a 16-mo follow-up.Further studies are needed to evaluate the long-term efficacy and safety of biodegradable stents in the treatment of intestinal strictures,particularly in the context of CD.

Synthetic Absorbable Surgical Sutures

This paper reviewed all types of the polymer - based synthetic absorbable surgical sutures that have been commercially produced. The chemical component, biological and mechanical properties, and using effect of these sutures were discussed. The recent development and the possible coming research orientation in these areas were also presented.

Clinical features and literature review related to the material differences in thread rhinoplasty:Two case reports

BACKGROUND Thread rhinoplasty can trigger a reaction to thread material,which is a foreign body.We compared clinical features induced by absorbable and non-absorbable threads following thread rhinoplasty.CASE SUMMARY Two patients who underwent different thread materials showed different clinical courses and different Hounsfield unit(HU)values in computed tomography.Patients with absorbable thread showed high HU values similar to a metallic material,and the HU value of inflammation was similar to vascular tissues with a lot of water(250).In the intraoperative field,absorbable thread materials and micro-abscesses were observed.In contrast,in the case of a non-absorbable thread,an object presumed to be thread was seen on the computed tomography(CT),and the HU value of inflammatory tissues was less than 100.In both patients,post-operative HU decreased to less than 100 and the clinical course improved.In both cases,histopathologic findings revealed foreign body granuloma associated with inflammation.CONCLUSION Absorbable threads were more aggressive and are more easily detected on CT.

A review on biodegradable biliary stents: materials and future trends

Biliary stricture is defined as the reduction and narrowing of the bile duct lumen, which can be caused by many factors such as cancer and inflammation. Biliary stent placement can effectively alleviate benign and malignant biliary strictures. However, the commonly used plastic or metallic biliary stents are far from ideal and do not satisfy all clinical requirements,although several types of biodegradable biliary stents have been developed and used clinically. In this review, we summarized current development status of biodegradable stents with the emphasis on the stent materials. We also presented the future development trends based on the published literature.