Sandwich Cup Research Articles

Evaluation of our self-designed nanometer silicon membrane sandwich cup system for diagnosing tuberculosis.

A nanometer silicon membrane sandwich cup system was self-designed. It could concentrate the bacilli via 0.45-μm microporous filter membrane and semi-automate the acid-fast bacilli (AFB) by a bacteria-staining machine. The aim of the study was to assess the clinical value of our self-designed system for diagnosing tuberculosis (TB). A total of 1993 sputum specimens obtained from patients with confirmed or suspected TB were subjected to direct or concentrated specimens smear at XiangYa Hospital, Central South University between May 2012 and February 2013. In addition, all the specimens were also inoculated into Lowenstein-Jensen (L-J) media, and culture results were considered as the gold standard for calculating sensitivity and specificity. Compared with direct smear examination, an increased density of red stained bacilli was observed in the self-designed nanometer silicon membrane sandwich cup analysis under the microscope. The positive rate of the self-designed analysis was significantly higher than that of direct AFB smear [10.9% (217/1993) vs 6.2% (123/1993), P < 0.05]. The sensitivity of the self-designed system increased (97.3% vs 55.2%, P < 0.05) without a loss of specificity (100% vs 100%) for identifying positive TB cases compared with the direct smear method. The self-designed nanometer silicon membrane sandwich cup and semi-automatic bacteria-staining machine could more efficiently and rapidly detect the AFB in respiratory specimens than direct microscopy. This is a novel and safe examination, and it may replace direct smear examination for the diagnosis of patients with TB.

Fracture of Ceramic Liner and Head in a Total Hip Arthroplasty with a Sandwich Type Cup

Due to its advantages, ceramic-on-ceramic bearings have been widely used in young patients for almost 30 years. Long-term survivorship, low wear, and low biological reactivity to particles are some of its characteristics. Even though this material has had a lot of improvements, the risk of fracture is one of the concerns. There have been reports of fracture of ceramic in the acetabular liner and head but no fractures of both in the same patient. We report a case of a fracture in a sandwich type acetabular liner and the ceramic head in a patient involving ankylosing spondylitis. It occurred three years after the operation and with no history of direct trauma. We decided to change the bearing surfaces to metal polyethylene without removing the metal back. The patient is satisfied by the clinical results after a 5-year followup.

Bilateral fractures of alumina ceramic heads in total hip arthroplasty and subsequent ceramic re-fracture after revisional arthroplasty in sandwich ceramic cup

A case of bilateral fractures of both ceramic heads in total hip arthroplasty and subsequent re-fracture of ceramic component after revisional surgery with ceramic sandwich cup exchange is reported. The heads were a skirt-type and extra-long size. The fractures occurred 8 months after the operation without any trauma. The cause of the fractures might be the impingement between the neck and the ceramic liner rim. At revision surgery, the fractured ceramic heads were replaced with sandwich-type ceramic liner and heads with ball type. After 3 years of revision surgery, ceramic head and ceramic liner in left total hip arthroplasty were fractured without any trauma. The ceramic head and liner were replaced with metal head and polyethylene liner at re-revisional operation.

Fracture of a ceramic liner in a total hip arthroplasty with a sandwich cup

Alumina ceramic-on-ceramic total hip arthroplasty (THA) has been widely used due to its advantages such as low wear, scratch resistance, wettable surface and relatively low biological reactivity of the wear particles. Nevertheless, this material in THA still persists to be one of the major concerns about the risk of fracture, due to its brittleness. Many authors have reported a fracture of the ceramic head but few reported a fracture of the ceramic acetabular insert. In order to reduce the rigidity of the ceramic-on-ceramic coupling and prevent an impingement between the rim of the ceramic liner and the metal neck of the femoral stem, a modular acetabular component with a sandwich insertion (alumina/polyethylene/titanium) was proposed. We report the fracture of the ceramic acetabular liner of such a ceramic sandwich cup due to a slightly retroverted position of the cup that causes an impingement between the femoral stem and the rim of the insert. The fracture occurred 3 years after the operation without trauma. At revision the entire cup was replaced using a polyethylene liner without inner ceramic liner.

Alumina Femoral Head Fracture in Uncemented Total Hip Arthroplasty With a Ceramic Sandwich Cup

In total hip arthroplasty, insertion of a UHMWPE-coated ceramic sandwich liner dramatically reduces any risk related to the stiffness of the ceramic-ceramic coupling. We present a case of an alumina ceramic head fracture with a ceramic sandwich cup. The fracture occurred 16 months after the initial operation, without trauma. Impingement between the neck and posteroinferior portion of the liner rim had occurred. This was related to the traditional cross-legged sitting position of Koreans, which caused impingement between the neck and liner rim. Consequently, the taper became loose, and the resulting force bent the taper and fractured the head. We examined a peculiar case of ceramic femoral head fracture after implantation of an uncemented total hip arthroplasty with a ceramic sandwich cup and investigated the underlying cause.

Effect of bearing geometry and structure support on transient elastohydrodynamic lubrication of metal-on-metal hip implants

An effective lubrication can significantly reduce wear of metal-on-metal artificial hip joints. The improvement of the lubrication can be achieved through the optimisation of the bearing geometry in terms of a small clearance and/or the structural support such as a polyethylene backing underneath a metallic bearing in a sandwich acetabular cup form. The separate effects of these two factors on fluid film lubrication of 28 mm diameter metal-on-metal total hip joints under walking conditions were numerically investigated in this paper. The results show that a larger lubricant film due to the polyethylene backing can be significantly enhanced by the transient squeeze-film action, particularly during the stance phase, and a similar lubricant film can be developed for both the monolithic cup relying on the smaller clearance and the sandwich cup benefiting from the polyethylene backing. Both cup systems can function in a wide range of lubrication regimes, covering both mixed and fluid film, under the current design and manufacture conditions.

Mid-Term Results of Ceramic-on-Ceramic Total Hip Arthroplasty with Sandwich Cup

In ceramic-on-ceramic total hip arthroplasty (THA), modular acetabular component with a sandwich insertion was developed and evaluated mid-term clinical results. 35 hips had undergone cementless ceramic-on-ceramic THA with sandwich cup (Kyocera, Kyoto, Japan). The mean duration of follow-up was 5 years. 6 hips had undergone component revisions. The reasons for revision included infection in 1 hip, dislocation with loosening in 2 hips, alumina liner fractures in 2 hips, and cup dissociation in 1 hip. All femoral and acetabular components showed no loosening in the unrevised hips at the time of the last follow-up. None of the 29 unrevised hips had osteolysis.

Investigation into the effect of a sandwich acetabular cup upon lubricant film thickness in metal-on-metal total hip replacements

The development of a large lubricant film thickness generally depends upon the large elastic deformations of the bearing surfaces from the elastohydrodynamic lubrication (EHL) point of view. The deformation of the bearing surfaces of total hip joint replacements can be influenced by the material properties as well as the structural supports. A conceptual sandwich cup, which consists of a hemispherical metallic bearing shell bonded to a polyethylene backing, together with a solid metallic femoral head was considered in an EHL analysis for quasi-static conditions of load and speed to investigate the effect of the sandwich cup upon lubricant film thickness in total hip replacements. It was found that a reduction in the cup wall thickness of the metallic shell and an increase in the polyethylene thickness resulted in an increase in the predicted lubricant film thickness and a decrease in the hydrodynamic pressure. A general relationship was found between the film thickness and the metallic inlay thickness.

Bactericidal activity of various antibiotics against biofilm-producing Pseudomonas aeruginosa

Clinical isolates of Pseudomonas aeruginosa were collected from hospitals in Tehran, Iran, and identified using biochemical tests. A modified microtitre plate test was used to determine the biofilm-forming capacity of the isolates, measured with an enzyme-linked immunosorbent assay (ELISA) reader. Results showed that P. aeruginosa strain 214 was the most efficient at producing biofilm compared with the other strains. Observation of the bacterial biofilm on Teflon sheets and on a catheter using a scanning electron microscope showed greater biofilm formation on the catheter than on Teflon sheets. In this study, we investigated the bactericidal activity of fluoroquinolones, β-lactams, macrolides and aminoglycoside. The results showed differences in the antibiotic susceptibility of planktonic and biofilm cell populations. Fluoroquinolones showed more potent activity than the other antibiotics, and biofilms were completely eradicated by treatment with 16 × the minimum inhibitory concentration (MIC) of ciprofloxacin and 64 × MIC of ofloxacin, whereas all biofilms survived 2560 μg/mL of imipenem and ceftazidime. Production of an exopolysaccharide matrix is one of the distinguishing characteristics of biofilms. It has been suggested that this matrix prevents access of antibiotics to the bacterial cells embedded in the community. In this study, we also evaluated the permeation of antibiotics through alginate of P. aeruginosa strain 214 using a sandwich cup method. Macrolides were most efficient, showing 100% penetration; fluoroquinolones and β-lactams had a high permeation rate >75%, whereas the rates for aminoglycosides were low (amikacin = 59%; gentamicin = 73%).

Dissociation and fracture of alumina liner in alumina/alumina total hip arthroplasty with sandwich cup and their treatment

Dissociation and fracture of alumina liner in alumina/alumina total hip arthroplasty with sandwich cup and their treatment

Ceramic acetabular liner fracture in total hip arthroplasty with a ceramic sandwich cup

In total hip arthroplasty, a modular acetabular component with a sandwich insertion (alumina ceramics/polyethylene/titanium) was proposed. The polyethylene layer might reduce the rigidity of the ceramics and prevent an impingement between the ceramic liner rim and the femoral neck. A case of an acetabular liner fracture of the ceramic sandwich cup was presented. The fracture occurred 1.4 years after the operation without trauma. Because the ceramic liner rim was hit by the head following the impingement between the neck and the polyethylene, the cause of the fracture might be the stress concentration at the rim of the ceramic liner, of which the thickness was only 4 mm. At revision surgery, the fractured ceramic liner was replaced with a polyethylene liner without inner ceramic liner.

Five-year follow-up with a ceramic sandwich cup in total hip replacement.

The results of the first 56 consecutive total hip replacements using a new cementless, sandwich (alumina-polyethylene-titanium) acetabular component are reported. From March 1994 to March 1995 we operated on 39 female and 17 male patients; their mean age was 62.8 years (range 32-85 years). The Harris Hip Score was used for clinical evaluation. X-rays were examined according to the DeLee and Charnley method. At an average follow up of 62.4 months, 51 patients had complete clinical and radiographic data. For them, we recorded a good clinical result (average HHS 90.6), and we could detect no acetabular radiolucencies on X-rays. At the 5-year follow-up the results of this ceramic acetabular cup are quite encouraging. As a matter of fact, although the clinical results are very similar to those reported by other authors with conventional ceramic-polyethylene coupling prosthesis, the absence of periacetabular radiolucency and socket migration could mean less debris formation, less acetabular wear and, consequently, a longer life of the implant.

A sandwich cup method for the penetration assay of antimicrobial agents through Pseudomonas exopolysaccharides.

We developed new sandwich cup method to assay the penetration of various antimicrobial agents through Pseudomonas exopolysaccharides. Using alginate extracted from mucoid-type Pseudomonas aeruginosa and gellan gum from Pseudomonas elodea, the role of exopolysaccharides as a barrier against drug penetration was examined. The penetration of positively charged hydrophilic drugs such as aminoglycosides and polypeptides was markedly inhibited by the gels tested, but that of beta-lactams, quinolones, and macrolides was not inhibited. The penetration of gentamicin was strongly influenced by the gel concentration, the solution to be used, and the presence of Ca2+. These results suggest that the microenvironment at the infection site could greatly influence drug penetration through biofilms in vivo.