1/12. Wear-through of a modular polyethylene liner: four case reports.Four patients in whom the S-ROM Total Hip System Polydial polyethylene liner was used illustrate the importance of, and difficulties in, detecting polyethylene wear-through before a complete acetabular revision is necessary. The patients in these cases had full thickness polyethylene wear-through 11 or more years after total hip arthroplasties. Dorr and Livermore wear measurements from radiographs of the patients underestimated the actual wear and did not indicate wear-through. Because excessive head penetration was not evident radiographically with the S-ROM components, the cases showed the necessity of using additional measures to diagnose wear-through, particularly with these components. Repeat radiographs at a higher kilovoltage were used to better visualize the outline of the femoral head, and hip aspiration was used to diagnose metallosis. These cases also showed the importance of yearly followup evaluations, especially 10 or more years after surgery for patients with the S-ROM Polydial locking mechanism.- - - - - - - - - - ranking = 1keywords = metal (Clic here for more details about this article) |
2/12. osteolysis in a cementless, second generation metal-on-metal hip replacement.A 65-year-old man with osteoarthritis of the hip underwent a cementless total hip replacement with a modern generation, metal-on-metal bearing. Two years later the patient presented with localized osteolysis at the tip of the femoral stem. At the time of revision, the stem was found to be well-fixed. Extensive analyses of the bearing surfaces and periprosthetic tissues were done. There was minimal bearing surface wear and only small numbers of inflammatory cells, such as macrophages, in the tissues, and it was concluded that this was not a typical case of particle-induced osteolysis. All cultures and laboratory studies were negative for infection. This case report supports the multifactorial nature of osteolysis, which includes the osteolytic potential of joint fluid access to and fluid pressures within, the effective joint space.- - - - - - - - - - ranking = 10keywords = metal (Clic here for more details about this article) |
3/12. Non-operative management of a peri-prosthetic subcapital fracture after metal-on-metal Birmingham hip resurfacing.We describe a patient who sustained a peri-prosthetic fracture of the femoral neck two weeks after undergoing a resurfacing procedure for osteoarthritis of the hip. The fracture was minimally displaced and a satisfactory outcome was obtained following conservative treatment.- - - - - - - - - - ranking = 8keywords = metal (Clic here for more details about this article) |
4/12. Massive wear of an incompatible metal-on-metal articulation in total hip arthroplasty.We report on a case of massive wear because of an incompatible metal-on-metal combination. In a 62-year-old man, a cobalt-chromium (CoCr) inlay and a stainless steel head were paired by accident. Because of persistent pain, revision surgery was performed 7 months later. Histologic analysis of the surrounding tissue revealed massive metallosis. The wear volume was increased by a factor of 18 for the head and 2 for the cup compared with normal metal-on-metal articulation. The serum concentrations of chromium and cobalt were increased by a factor of 20 and 4 over levels of a healthy population, respectively. Incompatible metal-on-metal combinations should be revised immediately. In case of delayed diagnosis, no metal-on-metal articulation should be implanted because of the high volume of metal in the human body.- - - - - - - - - - ranking = 18keywords = metal (Clic here for more details about this article) |
5/12. Resurfacing arthroplasty of the hip in osteopetrosis.A 34-year-old woman with a benign form of osteopetrosis developed osteoarthritis of the hip. In order to avoid the difficulties associated with inserting the femoral component of a conventional total hip arthroplasty, a hybrid metal-on-metal resurfacing was performed. There were several technical challenges associated with the procedure, including the sizing of the component, press-fit fixation of the acetabular component and femoral head preparation, as well as trying to avoid a fracture. No surgical complication occurred. After more than a year following surgery, the patient showed excellent clinical function and remained satisfied with the outcome. We conclude that the hybrid metal-on-metal resurfacing arthroplasty represents a valuable option for the treatment of patients with osteopetrosis and secondary hip osteoarthritis.- - - - - - - - - - ranking = 4keywords = metal (Clic here for more details about this article) |
6/12. Lead arthropathy: a cause of delayed onset lead poisoning.patients who suffer gun shot wounds often have retained bullet fragments within their bodies. These are usually of no clinical consequence. We describe three patients with retained bullets within their hip joints. One of these patients, who had extensive ground intra-articular bullet fragments and secondary osteoarthritis of the hip, presented with signs, symptoms, and laboratory data consistent with lead intoxication. The bullet and metallic fragments were removed surgically with good clinical response. Two patients whose bullets were implanted entirely within the femoral head and whose joints showed smaller degrees of lead fragmentation had no symptoms of lead intoxication. The degree of intra-articular fragmentation of the bullet and the surface area of lead exposed to synovial fluid are emphasized as decisive factors with respect to appropriate therapy.- - - - - - - - - - ranking = 1keywords = metal (Clic here for more details about this article) |
7/12. Bipolar hip arthroplasty without acetabular bone-grafting for dysplastic osteoarthritis. Results after 6-9 years.The authors report the clinical and radiographic results of 36 bipolar hip arthroplasties after performing excavation of the steep and shallow acetabulum without acetabular bone-grafting for dysplastic osteoarthritis. The procedures were carried out between 1981 and 1985. Survivorship analysis showed that 84.6 of the bipolar hip arthroplasties were retained for 8 years. Twenty-nine patients, which were followed for 6-9 years after surgery, were reviewed. Severity of acetabular dysplasia was classified according to the method of Crowe. Class 1 included 17 hips and class 2 included 12 hips. The average preoperative clinical score was 49 points. The average postoperative clinical hip score improved to 87 points after 6 years. Twenty-seven of the 29 hips assessed were classified as either excellent or good by Charnley's function score. Stress fracture, due to excessive acetabular excavation at the time of surgery, and femoral component loosening were major symptomatic complications. The cessation of radiographic evidence of migration of the bipolar socket was recognized in 25 of 29 procedures at 6 years after surgery (86.2%). Cineradiographic study demonstrated that the abduction motion under standing position for 20 of 24 hip joints functioned dominantly at the inner-bearing and metallic-stem interface.- - - - - - - - - - ranking = 1keywords = metal (Clic here for more details about this article) |
8/12. Metallosis caused by alumina ceramic screw fixation of grafted bone in a bipolar hip endoprosthesis.We report a case of metallosis due to ceramic fragments in the inner bearing surface of the polyethylene cup of a bipolar hip prosthesis with fracture of the alumina ceramic screws used for grafted bone fixation. After bone-grafting acetabuloplasty with a Bateman bipolar endoprosthesis, gradual migration of the outer head occurred, and fracture of the screws was observed. Seven years after the operation, radiographs showed severe metallosis of the surrounding tissues. At revision, marked wear of the inner head was seen. Detailed examination revealed that many rough-edged ceramic particles originating from the fractured ceramic screws had become embedded in the inner surface of the polyethylene bearing insert. These extremely hard ceramic fragments had entered the prosthetic joint space during joint movement, thereafter causing continuous abrasion of the metal head. After revision, the concentration of the constituents of the prosthesis alloy in the serum decreased toward control levels. To prevent serious complications like those in the present case, screws should be inserted more than 1 cm from the outer head of a bipolar endoprosthesis, and the outer head should be removed as soon as possible if it comes into contact with the screws.- - - - - - - - - - ranking = 3keywords = metal (Clic here for more details about this article) |
9/12. sarcoma of bone-cement membrane: a case report and review of the literature.The development of a cancerous tumour at the site of total joint replacement is a rare but virtually always fatal event. The previously unreported scenario of a patient who was found to have a malignant fibrous histocytoma at the bone-cement membrane after revision for a loose total hip prosthesis is reported. Recent biologic information evaluating the response of mesenchymal cells to metallic debris suggests that the environment surrounding a loosened prosthesis may provide conditions appropriate for the development of a sarcoma.- - - - - - - - - - ranking = 1keywords = metal (Clic here for more details about this article) |
10/12. Early failure of a carbon-fiber composite femoral component.carbon fiber has a theoretical advantage over other materials for hip arthroplasty. It has a modulus of elasticity closer to that of bone than other materials. This property has been used in the production of a femoral component for use in hip arthroplasty. Isoelasticity could avoid the problems of stress shielding prevalent with other uncemented metal prostheses; however, the early failure of one such prosthesis due to implant breakage at the neck-body junction is reported.- - - - - - - - - - ranking = 1keywords = metal (Clic here for more details about this article) |
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