Papers by Keyword: Bearing Surfaces

Abstract: The hip is one in every of the various joint at intervals the body. The correct operating of this joint is essential. For the aim once the hip is injured whole, a substitution procedure of the entire joint ought to be done to reinstate its operating, that is known as absolute hip surgical process. It is finished with the assistance of inserts of various biomaterials, as an example, polymers, metals, and pottery. The primary issues with regard to the utilization of various biomaterials are the reaction of the body's instrument to wear trash. Throughout this audit, biomaterials that are developing is talked regarding aboard the wear and tear and tear conduct and instrument. To boot, the numerous properties of the biomaterials are talked regarding aboard the expected preferences and drawbacks of their utilization. Further, the blends of various biomaterials at intervals the articulating surfaces are cleft and so the problems regarding their utilization are assessed. This paper hopes to passes away an in depth review of the trauma fringe of bearing surfaces of hip prosthetic devices. Additionally, this paper can offer AN ordered blueprint of the materials nearby their favorable circumstances and detriments and besides the conceivable outcomes of use. Keywords: - Hip implant; Biomaterials; Wear mechanism; Bearing surfaces; Polymers

Abstract: The paper deals with modern designs of crankshaft bushings used in internal combustion engines. It delineates the prospects of polymer coatings to ensure additional protection of lead bronze bushings in the event of emergencies associated with a temporary loss of lubrication. For this purpose, a polymer composition of silicone polyorganosiloxane and fluoro-epoxy lacquers is proposed. Tribotechnical results are provided for polymer-coated bushings: 1) in a full-film lubrication condition, 2) in boundary conditions (with lubricant residues once the unit has been switched off) and 3) in dry conditions (with no lubrication after a long standstill). A thin-layer (3...5 μm) polymer coating based on polyorganosiloxane and fluorine can be used on the bearing surfaces of the shells of highly loaded bearings in order to increase antifriction properties, especially with limited lubrication and possible scores in a bearing.

Abstract: In the article are shown the results of tests on friction and wear behavior of friction couples sapphire against sapphire or tetragonal dioxide of zirconium. Tribological characteristics of tetragonal dioxide of zirconium (Y,Ce,Hf)-TZP in pair with a counter body from sapphire are essentially better than characteristics of the couple sapphire/sapphire (friction force lower 1,3 times, linear wear 1,5 times).

Abstract: Wear debris contributes to the development of granulomatous debris disease and loosening. It is accepted that hydroxyapatite ceramic (HA) will bond a prosthesis to bone.[1,2] Osteolysis has not been seen for several years after implantation but cases are now emerging [3]. Is HA still working Should we use hard on hard bearings Should we abandon polythene liners With a modular hip system, patients with polythene acetabular liners have been compared with those with ceramic liners. Polythene liners wear out and patients with a life expectancy of more than ten years should have ceramic/ceramic bearings.

Abstract: Total hip arthroplasty (THA) in patients with sequelae of the hip joint infection is a technically challenging procedure. In addition, the majority of such patients are less than fifty years old, so it has been reported that they have higher prevalence of complication and failure of component fixation. Alumina-on-alumina couplings are an attractive alternative and may offer a promising option for such young active patients. We analyzed 33 primary cementless alumina-onalumina THAs (PLASMACUP®SC-BiCONTACT® system incorporating BIOLOX® forte) that had been performed in patients who had sequelae of the hip joint infection. The average age of the patients was 37.8 years (range, 19-68 years) and 26 patients were younger than 50 years old. They were followed-up for more than 5 years (average, 74 months; range, 60-93 months). All hips had no recurrence of hip joint infection. The mean Harris hip score improved from 59.8 points to 93.5 points. All of the implants had radiographic evidence of a bone ingrowth and no radiological loosening was found. During the follow-up period, no cup or stem was revised and no periprosthetic osteolysis was observed. Nonunion of the osteotomized greater trochanter occurred in one hip, but no postoperative infection or ceramic failure was observed. The 5-year minimum follow-up clinical results of modern alumina-on-alumina THAs performed in patients with sequelae of the hip joint infection were encouraging with regard to osteolysis and implant stability. Our findings show that this alternative articulation offers a reliable solution for these young patients with long-standing anatomic abnormalities of the bone and soft tissues.

Abstract: Medial placement of a cementless acetabular component into or beyond the medial wall of a shallow, dysplastic acetabulum is a technique to enhance its coverage during difficult total hip arthroplasty (THA). Dysplastic hips almost always need small size of acetabular component, so an accelerated polyethylene wear can occur when a conventional bearing surface is used. Modern alumina-on-alumina couplings can be an alternative for these patients. We evaluated the clinical results of 43 medially placed cementless acetabular components (PLASMACUP®SC) incorporating a modern alumina bearing surface (BIOLOX® forte). Acetabular components were inserted medially beyond the ilioischial line and, therefore, beyond the level of the cortical bone of the cotyloid notch, and followed up for more than 5 years (range, 60 – 93 months). In 14 hips, the medial acetabular wall was perforated purposefully and the medial aspect of the cup was placed beyond both the ilioischial and the iliopubic line on radiographs. The mean Harris hip score improved from 55.3 points preoperatively to 94.5 points postoperatively. Postoperatively, the hip center migrated 12.1 mm medially and 1.5 mm inferiorly. The average amount of cup protrusion beyond the ilioischial and the iliopubic line was 3.1 mm and 1.9 mm, respectively. The average superolateral coverage of the cup was 98.5 percent. During follow-up, no osteolysis or loosening of acetabular components was observed and no revision was required. Medial placement of a cementless acetabular component into or beyond the medial acetabular wall offers predictable clinical results and durable fixation in modern alumina-on-alumina THA.

Abstract: Limitation in liner and head options available to the surgeon may be the most practical disadvantage of alumina-on-alumina total hip arthroplasty (THA). This may be more problematic in the revision THA. We evaluated the results of 57 revision THAs (average, 46.2 years old) performed with a contemporary alumina-on-alumina bearing surface after a 5-year minimum follow-up (average, 67 months; range, 60-85 months). A third generation alumina-on-alumina bearing (BIOLOX® forte, CeramTec AG) and a cementless PLASMACUP®-BiCONTACT® hip revision system (AESCULAP AG & Co.) had been used in all patients. Alumina bearing was chosen for a relatively young active patient in whom an acetabular bone defect was not severe and an extremely long neck of artificial head was not required for the restoration of hip joint mechanics. The average Harris hip score improved from 65.0 points to 88.9 points. No implant loosened, no stem or cup was re-revised, and no additional reoperations were required. Ceramic wear was undetectable in 14 hips where differentiation of the femoral head from the cup was possible on radiographs and no osteolysis was observed. During the follow-up period, no hip demonstrated signs of infection or ceramic failure. Short-term results of revision THAs performed with analumina-on-alumina bearing are encouraging. We believe that physiological age and activity level of a patient, severity of acetabular bone loss, and availability of alumina head and liner options required for the restoration of proper limb length and joint stability should be considered to choose this alumina bearing surface during the revision THA.