ABSTRACT
@#Introduction: The lubricant thickness in clearance between bearing surfaces for metallic hip implants are currently incapable of accommodating the motion experienced (high load and low entraining motion) in hip walking cycle. Thus, micro-dimpled surfaces were introduced onto surfaces of metallic acetabular cups to improve lubricant thickness. Micro-dimpled surface is a method of advanced surface improvement to increase the lubricant thickness in various tribological applications, such as hip implants. However, the application of micro-dimpled surfaces in hip implants has not yet been explored adequately. Therefore, this study aims to identify the influence of micro-dimpled depth on lubricant thickness elastohydrodynamically for metallic hip implants using Fluid-Structure Interaction (FSI) approach. Methods: Fluid-Structure Interaction (FSI) approach is an alternative method for analysing characteristics of lubrication in hip implant. Dimples of radius 0.25 mm and various depths of 5μm, 45μm and 100μm were applied on the cup surfaces. The vertical load in z-direction and rotation velocity around y-axes representing the average load and flexion-extension (FE) velocity of hip joint in normal walking were applied on Elastohydrodynamic lubrication (EHL) model. Results: The metallic hip implants with micro-dimpled surfaces provided enhanced lubricant thickness, namely by 6%, compared to non-dimpled surfaces. Furthermore, it was suggested that the shallow depth of micro-dimpled surfaces contributed to the enhancement of lubricant thickness. Conclusion: Micro-dimpled surfaces application was effective to improve tribological performances, especially in increasing lubricant thickness for metallic hip implants.
ABSTRACT
Emulsões óleo de oliva/água, na presença de agentes emulsionantes não-iônicos, foram avaliadas quanto à estabilidade física. Assim, prepararam-se emulsões fazendo uso de diferentes emulsionantes, sendo um hidrofílico e o outro lipofílico, nas diferentes proporções. Às emulsões mais estáveis, adicionaram-se agentes auxiliares da emulsificação, visando otimizar a estabilidade; e estudos de estabilidade foram conduzidos, submetendo as amostras em condições e períodos diversos de armazenamento. Para caracterização da estabilidade, as amostras foram examinadas macroscopicamente e submetidas às análises de pH, centrifugação, viscosidade, potencial zeta e distribuição de tamanho de partícula. Os resultados demonstraram que as emulsões óleo de oliva/água não apresentaram alteração, ou seja mantiveram-se estáveis, quanto às propriedades organolépticas, bem como físicoquímicas, quando armazenadas à temperatura ambiente e protegidas da luz. Das emulsões obtidas, as que apresentaram maior estabilidade provêm da associação de agentes emulsionantes que resultaram em equilíbrio hidrofílico-lipofílico (EHL) equivalente a 12. As emulsões provenientes da associação de agentes emulsionantes que possuem cadeias de ácidos graxos insaturados similares ao óleo de oliva produziram estabilidade máxima, demonstrando que a similaridade estrutural entre os componentes da fase oleosa e os agentes emulsionantes é essencial para a estabilidade da emulsão.
Olive oil-in-water emulsions, developed with non-ionic emulsifiers, were assessed with regard to physical stability. Emulsions were prepared with two different emulsifiers, one of which was hydrophilic and the other lipophilic, in various proportions. To improve emulsion stability, auxiliary emulsifiers were added to the stablest emulsions and stability studies were carried out, in which the samples were stored for different periods and under various conditions. To test emulsion stability, the samples were examined macroscopically and various physicochemical properties, such as pH, centrifugation, viscosity, zeta potential and particle size distribution, were assessed. The results showed that olive oil-in-water emulsions are organoleptically and physicochemically stable, when stored at room temperature and protected from the light. Out of the emulsions developed, the most stable was based on an emulsifier blend that resulted in a hydrophilic-lipophilic balance (HLB) of 12. A blend of emulsifiers with unsaturated fatty acids of similar chain length to that of olive oil produced the stablest emulsions, showing that structural similarity between the hydrocarbon moieties of the oil phase and the surfactant is essential to successful emulsion stabilization.
Subject(s)
Emulsions , Emulsifying Agents/analysis , Vegetable FatsABSTRACT
BACKGROUND: The use of choledochoscopy has been increasing lately in open and laparoscopic surgery for bile duct stones. Intraoperative choledochoscopy is useful for assessing the biliary trees and stones and for assisting in the removal of bile duct stones. However, large or impacted bile duct stones are difficult to remove using choledochoscopy alone. Application of electrohydraulic lithotripsy (EHL) seems to be suited for these difficult cases. METHODS: Twenty-six (26) patients with bile duct stones were treated with intraoperative cho ledochoscopic EHL to remove stones which could not be retrieved using stone forceps, a basket, saline flushing, or a Fogarty catheter. We divided the 26 cases into two groups: 12 cases of laparoscopic surgery and 14 cases of open surgery. These cases were further divided into two groups: common bile duct stones and intrahepatic duct stones RESULTS: The indications of EHL in laparoscopic surgery for common bile duct stones were large stones in 2 cases and impacted stones in 4 cases. Eighteen (18) patients with intrahepatic duct stones were treated with EHL for impacted stones. Stone clearence rate was 88.5%, and complications occurred in 3 cases (11.5%). One case of a biliary fistula was managed conservatively, and two cases of mucosal bleeding of the bile duct were spontaneously controlled. CONCLUSION: Intraoperative choledochoscopic electrohydraulic lithotripsy is a safe and effective method for removing large or impacted bile duct stones.
Subject(s)
Humans , Bile Ducts , Bile , Biliary Fistula , Catheters , Common Bile Duct , Flushing , Hemorrhage , Laparoscopy , Lithotripsy , Surgical InstrumentsABSTRACT
OBJECTIVE: Intrahepatic stones provide a quite different spectrum of problems faced by surgeons in the Eastern hemisphere. Although unilateral left intrahepatic stones have been treated by left hepatic lobectomy, bilateral or right intrahepatic stones can be even more troublesome because they frequently cannot be completely removed by conventional surgical stone extraction procedure. Recently, the use of a flexible fiberoptic choledochoscope, electrohydraulic lithotriptor(EHL) and dilators make it possible to completely remove intrahepatic stones by nonsurgical procedures in the majority of cases. METHODS: During the last 5 years, we treated intrahepatic stones in 114 patients with a fiberoptic choledochoscope, EHL and dilators via percutaneous transhepatic route. For construction of percutaneous transhepatic routes, we punctured intrahepatic ducts by ultrasonographic guidance and then dilated the tracts by PTBD set(Nipro Co., Japan) under fluoroscopic guidance. Choledochoscopy were performed at 4-6 weeks later, and Dormina basket, EHL, balloon or bougie dilators were used for removal of stones. RESULTS: Success rates according to the locations of stones were 87.5%(14/16) in unilateral right intrahepatic stones, 92.9%(39/42) in unilateral left intrahepatic stones, and 89.3%(50/56) bilateral intrahepatic stones. Overall success rate was 90.4%(103/114). Causes of incomplete removal of the stones in our patients included the failure of construction or maintenance of percutaneous transhepatic routes in 4 cases, intrahepatic bile duct stricture proximal to impacted stones in 3, acute ductal angulation in 2, and stones located at the very distal branches of intrahepatic ducts in 2 cases. Complications associated with the procedure were transient fever in 8 cases, severe hemobila in 2 cases and biliary perforation in 3 cases. CONCLUSON: These results suggest that percutaneous transhepatic choledochoscopic approach is a relatively safe and effective method for treatment of intrahepatic stones.
Subject(s)
Humans , Bile Ducts, Intrahepatic , Constriction, Pathologic , FeverABSTRACT
BACKGROUND/AIMS: Obstructive jaundice is developed from the cholangiocarcinoma, biiliary tract stone, biliary benign stricture and pancreatic head cancer and is rapidly progress to cholangitis or sepsis. So early decompression, accurate diagnosis and treatment are very important. Percutaneous transhepatic choledocoscopy (PTCS) and endoscopic retrograde choledocoscopy (ERCS) have been used for evaluation of the obstructive jaundice. We performed, through the PTCS, electrohydraulic lithotripsy (EHL) for biliary tract stone rernoval, biopsy for diagnosis of biliary stric and self expandible metalic coil stent (EndocoilTM stent, Instent Co.) insertion on biliary stricture to evaluate the usefullness of PTCS in patients with obstructive jaundice. METHODS: Between Auguest 1994 and September 1995, PTCS was performed in 37 patients with obstructive jaundice. First, percutaneous transhepatic biliary drainage (PTBD) with 7Fr. drainage tube was done. Three days later, we exchainged the 7Fr. drainage tube with 16Fr.. Seven days later, through the PTCS, we performed EHL, biopsy and EndocoilTM stent insertion.
Subject(s)
Humans , Biliary Tract , Biopsy , Cholangiocarcinoma , Cholangitis , Constriction, Pathologic , Decompression , Diagnosis , Drainage , Head and Neck Neoplasms , Jaundice, Obstructive , Lithotripsy , Sepsis , StentsABSTRACT
BACKGROUND/AIMS: Electrohydraulic lithotrypsy(EHL) under cholangioscopic control has been performed for difficult bile duct stones. The percutaneous transhepatic approach is technically easy and useful in diagnosis and treatment of bile duct obstruction and stones. Biliary stenting with self expanding metal stent is gaining increasingly wider acceptance as a palliative treatment of bile duct obstruction. METHODS: Between Sep. 1994 and Sep. 1996, EHL under choledochoscopy by percutaneous transhepatic approach was performed in 30 cases(Male: 13, Female: 17). After PTBD with 7F pig tail catheter, the percutaneous transhepatic passage was dilated over guide wire with dilaters of increasing size up to 16Fr in 3-Sdays. In one week, after fistula had been estabilished, choledochoscopy was performed. RESULTS: (1) Mean age was 61.3 years. Mean stone number was 2.5. And mean stone size was 1.6 X 2.3 cm. (2) Com.plete removal of the stone was achieved in all patients(100%). (3) There were no serious complications. (4) In six cases, Endocoils were implanted with successful decompression of obstructions and simultaneous removal of biliary stones located at both side of stricutre. CONCLUSIONS: Percutaneous transhepatic choledochoscopy is easy and safe and assists in the diagnosis and treatment of biliary stricture and the management of difficult CBD stone.
Subject(s)
Female , Humans , Bile Ducts , Catheters , Cholestasis , Common Bile Duct , Constriction, Pathologic , Decompression , Diagnosis , Fistula , Palliative Care , StentsABSTRACT
Electrohydraulic lithotripsy (EHL) is a method used to breakup the stone by electric discharge in the presence of liquid medium. Recently we experienced a case of successful common bile duct stone removal after EHL during choledochoscopy via T-tube tract, which was the first case of EHL in biliary tract stone in Korea. A 65-year-old female patient was admitted to our hospital because of generalized pruritus after cholcystectomy with T-tube insertion. Obtained cholangiogram showed retained CBD stone which was implssible to remove by Dormian basket and tto dissolute by monooctanoin. After only one session of EHL, we can disintergrat CBD stone into several small pieces and removal of stone was easily done by Basket. After Small cut endoscopic sphincterotomy (EST) remained distal impacted stone was freely passed and control choledochoscopy and cholangiogram showed no remained stone. We think that EHL may be play a potential role in removal of biliary tract stones as in urinary tract stones.
Subject(s)
Aged , Female , Humans , Biliary Tract , Common Bile Duct , Korea , Lithotripsy , Pruritus , Sphincterotomy, Endoscopic , Urinary CalculiABSTRACT
Rigid ureteroscopy is now an established technique for the management of ureteral stones and the diagnostic procedure of ureteral lesions. The results of ureteroscopic stone removal were reviewed in 153 patients (1 patient ; bilateral). From October 1989 to August 1990, 163 patients underwent ureteroscopic removal of ureter stones. There were 53 female and 100 male patients between 17 and 72 years old. In all patients with ureteral stones surgical intervention was indicated for the obstruction with deteriorating kidney function, infection or severe and prolonged pain. All procedures were performed under epidural anesthesia. Stones were extracted, using grasping forceps or stone baskets with or without electrohydraulic lithotriptor (EHL) under direct visual control. Success of ureteroscopic removal was related to the location of the calculus : 98.2% in the distal, 88.2% in mid and 79.2% in the proximal ureter (overall success rate was 94.2% ). The associated number of complications was low, with most patients being treated conservatively. We conclude that ureteroscopic removal of ureteral stone under direct vision can be done safely and be the first choice of management for the ureteral calculi.