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[Magnetic resonance tomography in patients with a heart valve prosthesis].

Artificial valve prostheses are often regarded as a contraindication for magnetic resonance imaging (MRI), although preliminary in vitro studies suggested, that patients with these metallic implants might safely undergo MR examination. This study reports on the experience with a group of 89 patients with 100 heart valve prostheses who were examined by spin-echo MR and gradient-echo MR. MR examination was performed in all patients without complications. The spin-echo sequence showed advantages in the depiction of anatomical structures like paravalvular abscesses. Anatomical structures adjacent to the artificial valve were clearly visible and the metal components of the valves showed no or only small artifacts. Artifacts were accentuated when using gradient-echo sequences. Gradient-echo sequences provided valuable information regarding the presence of valvular insufficiency. Physiological valvular regurgitation was easy to differentiate from pathological paravalvular or transvalvular regurgitation. These results demonstrate that patients with artificial valve prostheses can be imaged by MR without risk and that prosthesis-induced artifacts do no interfere with image interpretation.

Abscess↗

Endovascular repair of aortic allograft aneurysmal degeneration: a case report.

Aortoenteric graft fistula remains a dreadful complication of aortic surgery. Good results have been reported using in situ graft replacement with arterial allografts. Late aneurysmal degeneration of the graft itself may necessitate further repair. We report the case of such an aneurysmal degeneration 7 years after implantation of the allograft. Endovascular repair was performed with a Vanguard device; complete exclusion was obtained immediately. At 6-month follow-up, the patient was alive and well. Duplex and computed tomography scans showed an excluded aneurysm with a slight reduction in size. Endovascular stent grafting may be a therapeutic option for treating patients with late allograft degeneration.

Aged↗

The Danish Hip Arthroplasty Register.

In Denmark (5.3 mill. inhabitants), a national register for total hip replacements was established in January 1995. During the first 4 years, 18,222 primary total hip replacements (THR), 3,343 revisions and 6,071 follow-up examinations have been registered. During the same period, the incidence of primary THR per 100,000 inhabitants has increased from 72 in 1995 to 93 in 1998. The mean age at the primary replacement was 68 years, 59% were women and in 75% primary arthrosis was the diagnosis. An increasing use of uncemented implants has been observed both in primary THR and in revision. 64% of the primary THR were cemented and in revisions of both components, 49% were cemented. The reasons for revision were aseptic loosening in 63% of the cases followed by dislocation in 12% and deep infection in 11%. When assessed by the Harris Hip Score, primary THR and revisions resulted in a considerable improvement in pain and function, with the best results after primary operation. After 3 years, the prosthesis survival of all primary THR was approximately 97%. The lowest survival was observed in younger men with a hybrid prosthesis, usually uncemented cup and cemented stem.

Aged↗

Antibiotic prophylaxis in total hip arthroplasty: effects of antibiotic prophylaxis systemically and in bone cement on the revision rate of 22,170 primary hip replacements followed 0-14 years in the Norwegian Arthroplasty Register.

We studied the effects of antibiotic prophylaxis, systemically and in bone cement, on the revision rate of cemented total hip arthroplasties (THAs) in data from the Norwegian Arthroplasty Register during the period 1987-2001. To have comparable groups, only THAs performed because of primary osteoarthritis, using cemented implants with documented good results, and high-viscosity cement were included. If systemic antibiotic prophylaxis had been given, only operations with cephalosporin or penicillin were selected. Cox-estimated survival relative revision risks (RR) are presented with adjustment for differences among groups in gender, age, cement brand, type of systemic antibiotic prophylaxis, type of prosthesis, type of operating room, and duration of the operation. Of 22,170 THAs studied, 696 THAs (3.1%) were revised, 440 (2.0%) for aseptic loosening and 102 (0.5%) for deep infection. We found the lowest risk of revision when the antibiotic prophylaxis was given both systemically and in the cement (15,676 THAs). Compared to this combined regime, patients who received antibiotic prophylaxis only systemically (5,960 THAs) had a 1.4 times higher revision rate with all reasons for revision as endpoint (p = 0.001), 1.3 times higher with aseptic loosening (p = 0.02) and 1.8 times higher with infection as the endpoint (p = 0.01). With the combined antibiotic regime, the results were better if antibiotics were given 4 times on the day of surgery (2,194 THAs), as compared to once (1,424 THAs) (p < 0.001), twice (2,680 THAs) (p < 0.001), or 3 times (5,522 THAs) (p = 0.02). Those who received systemic prophylaxis a single day 1, 2 or 3 times, as compared to 4 times, had a revision rate 1.8-3.5 times higher with all reasons for revision as endpoint, 1.5-3.1 times higher with aseptic loosening, and 2.7-6.8 times higher with infection. When we compared systemic prophylaxis 4 times in 1 day, no further improvement resulted in those given systemic prophylaxis for 2 days (1,928 THAs) or 3 days (717 THAs). In a subset of data including only the Charnley prosthesis, we obtained similar results. This observational study shows that the best results were recorded when antibiotic prophylaxis was given both systemically and in the bone cement, and if the systemic antibiotic was given 4 times on the day of surgery.

Adolescent↗

Effect of a buccal bioadhesive nystatin tablet on the lifetime of a Provox silicone tracheoesophageal voice prosthesis.

CONCLUSION: Daily application of a buccal bioadhesive slow-release nystatin tablet (100,000 IU per tablet) significantly increased the voice prosthesis lifetime in laryngectomized patients compared to conventional local cleaning of the prosthesis with an antimicrobial agent on a brush. OBJECTIVE: To investigate the effect of a buccal bioadhesive nystatin tablet on the lifetime of a Provox tracheoesophageal voice prosthesis in post-laryngectomy patients. MATERIAL AND METHODS: A buccal bioadhesive tablet, based on a spray-dried Amioca/Carbopol 974P mixture containing 10% (w/w) Carbopol 974P, was loaded with 100,000 IU of nystatin. Patients were included in the study when replacement of their voice prosthesis was required and were divided into three groups. Conventional daily local cleaning of the voice prosthesis by means of an oral nystatin suspension on a brush (Group 1; n = 7) was compared with application of one nystatin buccal bioadhesive tablet per day, after breakfast, on the gingiva above the upper canine (Group 2; n = 7). The control group (n = 5) used no antimicrobial agents. The lifetime of the prosthesis was followed and expressed in days. RESULTS: The lifetime of the voice prosthesis was significantly increased in Group 2 compared to Group 1 (p < 0.05; paired t-test), indicating that sustained release of nystatin in the oral cavity, by means of erosion of the tablet over a period of approximately = 8 h, is more effective at preventing microbial colonization of the prosthesis than local cleaning.

Acrylic Resins↗

Survival and complications are similar after Swanson and Sutter implant replacement of metacarpophalangeal joints in patients with rheumatoid arthritis.

We compared the survival, fracture, and deformation rates of Swanson and Sutter implants in a prospective series of 53 patients with rheumatoid arthritis (RA). Fifty-eight hands were operated on with 215 silastic implants. The Swanson group comprised 25 hands and 89 implants, and the Sutter group 33 and 126, respectively. Follow up was 58 (37-80) months. During a period of 48 months the survival of Swanson and Sutter prostheses did not differ significantly: 92% (95% CI 84% to 96%) and 97% (95% CI 92% to 99%), respectively. The fracture rate was high in both groups: 26 (34%) in the Swanson and 25 (26%) in the Sutter group. There was no significant difference between the groups in definite fracture rates of implants. The Sutter prosthesis appears to be at least as durable an implant in rheumatoid patients' metacarpophalangeal arthroplasty as the Swanson.

Adult↗

Receptor activator of nuclear factor kappaB ligand is expressed in resident and inflammatory cells in aseptic and septic prosthesis loosening.

OBJECTIVE: The pathogenesis of periprosthetic bone loss in aseptic and septic prosthesis loosening is unclear. There is considerable evidence that macrophages and osteoclasts play a key role in focal bone erosion and osteolysis around the prosthesis. RANKL (receptor activator of nuclear factor kappaB ligand) was shown to be a potent osteoclastogenic factor, and to be involved in bone destruction of myeloma and rheumatoid arthritis patients. Osteoprotegerin (OPG) is the natural RANKL inhibitor and may prevent periprosthetic bone loss. METHODS: The presence and distribution of RANKL, its receptor RANK and OPG in the periprosthetic interface of septically (n = 5) and aseptically (n = 6) loosened prostheses was examined by immunohistochemistry and immunoblotting. Additionally, the immunophenotype of the inflammatory infiltrate was determined [CD3, CD68, Ki-67, tartrate-resistant acid posphatase (TRAP)]. RESULTS: Aseptic and septic cases revealed a different histopathologic pattern. However, in all cases RANKL and RANK could be demonstrated in macrophages and giant cells. In addition, RANKL detected by immunoblot analysis proved to have the same molecular weight as a recombinant RANKL used as a control (31 kD and approximately 48 kD). OPG was detected in aseptic loosening, where macrophages showed a strong staining, but multinucleated giant cells were only weakly stained. A weak OPG staining was also observed in septic loosening. CONCLUSION: The pathogenesis of bone loss in septic loosening remains unclear, because the septic membrane bears few macrophages and giant cells, and half of them express OPG. In aseptic loosening, macrophages might not be stimulated by RANKL as a result of OPG expression. But multinucleated giant cells may be activated, as they hardly express OPG. They might be responsible for periprosthetic bone loss in aseptic loosening as a result of their RANKL and RANK expression.

Aged↗

New biliary endoprosthesis less liable to block in biliary infections: description and in vitro studies.

OBJECTIVE: To test in vitro stents made from a new biomaterial that is less liable to encourage adhesion of bacteria that may lead to blockage of the stent. DESIGN: Laboratory experiment. SETTING: University hospital, Italy. MATERIAL: 15 polyethylene biliary endoprostheses that had been removed endoscopically a mean of 151 days (range 55416) after insertion. PUPA, a biomaterial that contains polyamidoamine cross-linked to polyurethane chains. This can bind large quantities of heparin and HyalSx (hyaluronic acid at a different stage of sulphation) in a stable fashion. MAIN OUTCOME MEASURES: Incidence of blockage and growth of pathogens in the polyethylene biliary prostheses. Adhesion of pathogens to PUPA in vitro on electron microscopy. RESULTS: 12 of 15 polyethylene prostheses were blocked by brown concretions composed of calcium bilirubinate, palmitate, and little cholesterol. All concretions grew more than one pathogen, and the growth always included Escherichia coli. Of the 5 PUPA stents tested, only 1 had bacteria sticking to their surfaces. CONCLUSION: These results confirm previous studies that showed that HyalSx appreciably inhibited the adhesion of bacteria and is therefore a suitable material for the manufacture of biliary stents.

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Revision total knee arthroplasty with the total condylar III system: a comparative analysis of 71 consecutive cases of osteoarthritis or inflammatory arthritis.

BACKGROUND: As revision total knee arthroplasty surgery is becoming more common, it is necessary to evaluate how individual revision prosthesis systems perform in degenerative and inflammatory arthritides. In this study, results of the use of the Total Condylar III (TC III) system in osteoarthritis (55 knees) were compared to results of its use in inflammatory arthritis (16). METHODS: Patients were followed radiographically for 5.9 (3.0-10.2) years and clinically for 3.0 (0.2-6.8) years, using re-revision as the endpoint. RESULTS: At 1 year after revision and at final follow-up, the total Knee Society knee score, function score and range of motion had improved (p < 0.001) with no differences between osteoarthritis and inflammatory arthritis. No knee had definite component loosening, although 23 knees had asymptomatic radiolucent lines. Complications comprised 4 infections, 1 patellar pain syndrome and 1 rupture of the patellar tendon. Using any re-revision of the prosthesis as the endpoint, 5-year survival was 95% and 8-year survival was 94%. INTERPRETATION: Concentration of demanding revision knee arthroplasties to a few hands led to good or excellent knee joint knee score results in four-fifths of the patients, and showed good outcome with the TCIII system. In spite of ligamentous laxity, propensity to develop infections, bone destruction and poor general health, patients with inflammatory arthritis had results similar to those with osteoarthritis.

Adult↗

Improved aero-anaerobe recovery from infected prosthetic joint samples taken from 72 patients and collected intraoperatively in Rosenow's broth.

INTRODUCTION: Recovery of the bacteria responsible for prosthetic joint infections is a major problem, which is due in part to the alteration of their ability to grow by storage during transportation to the laboratory. METHODS: In this prospective study, we assessed the benefit of inoculating an enriched liquid medium (Rosenow's broth) with intraoperative samples from 72 patients with prosthetic joint revision due to infection. We compared the results of culture of specimens collected in a standard receptacle with the results for specimens collected in Rosenow's broth. RESULTS AND INTERPRETATION: 144 samples were taken by each of the 2 collection methods for subsequent culture. Concordance between standard and Rosenow samples was observed for 52 of the 58 strains cultured on agar and for 42 of the 97 strains (p < 0.001) which grew only in liquid medium. Infection would not have been diagnosed in 26 patients (almost one-third of all patients) without combining sample collection in Rosenow's broth with standard collection. The bacteria that were not recovered from standard samples but which were recovered from those collected in Rosenow's broth included not only strict anaerobes, in particular Propionibacterium acnes, but also coagulase-negative staphylococci and streptococci.

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Does cement increase the risk of infection in primary total hip arthroplasty? Revision rates in 56,275 cemented and uncemented primary THAs followed for 0-16 years in the Norwegian Arthroplasty Register.

INTRODUCTION: The cementation of a total hip prosthesis may cause bone necrosis, either by direct toxicity or by generation of heat during the polymerization process. This necrotic bone may create conditions that encourage the growth of bacteria. We compared the revision rates due to infection in primary uncemented total hip arthroplasties (THAs) with those of cemented THAs with antibiotic-loaded cement and to those of cemented THAs without antibiotic cement. METHODS: Data from the Norwegian Arthroplasty Register for the period 1987-2003 were used. To have comparable groups, we analyzed only primary THAs performed because of primary osteoarthrosis, and where both the acetabular and the femoral component of the prosthesis were either uncemented or cemented (n = 56,275). RESULTS: In total, 252 revisions due to infection were reported. Compared to the uncemented THAs (n = 5,259), the risk of revision due to infection for THAs without antibiotic cement (n = 15,802) was increased 1.8 times (CI 1.0-3.1; p = 0.04). No differences could be detected when compared to THAs with antibiotic-loaded cement (n = 35,214) (RR 1.2, CI 0.7-2.0; p = 0.5). The average operating time for uncemented THAs was 15 min less than for cemented THAs. INTERPRETATION: The risk of revision due to infection was the same for uncemented and for cemented arthroplasties with antibiotic-loaded cement, but higher for cemented arthroplasties without antibiotic cement. Our findings can be explained by reduced resistance to infection caused by the cement, which appears to be neutralized by adding antibiotic to the cement.

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Is "aseptic" loosening of the prosthetic cup after total hip replacement due to nonculturable bacterial pathogens in patients with low-grade infection?

BACKGROUND: Loosening of the prosthetic cup is the limiting factor in the service life of total hip prostheses (THPs). Despite effective culture methods, the detection of low-grade infection in patients with loose implants still presents a challenge. It is crucial to distinguish between "aseptic" loosening and loosening due to periprosthetic infection, so that appropriate treatment can be administered. We investigated whether aseptic loosening of the acetabular components of THPs is due to unrecognized infection. METHODS: From October through December 2002, a total of 24 patients with acetabular cup loosening were investigated. Only patients without clinical signs of infection and with negative results of bacteriologic culture of synovial fluid (obtained by preoperative aspiration) were included in the study. Intraoperative biopsy samples obtained from the neocapsule and synovia (e.g., the interface membrane) were examined by means of routine culture methods and by polymerase chain reaction (PCR) for detection of 16S ribosomal RNA (rRNA). Control subjects included 9 patients undergoing primary hip arthroplasty. RESULTS: C-reactive protein levels and erythrocyte sedimentation rates were slightly elevated in the group with loosening, compared with the control group, but the difference was not statistically significant. PCR and routine culture showed no microorganisms in either group, with the exception of 1 patient in the loosening group. CONCLUSIONS: PCR for detection of 16S rRNA in tissue specimens obtained from hip joints is not superior to routine bacteriologic culture techniques for detection of low-grade infections. However, these results demonstrate that the loosening of cups in THPs do not usually result from nonculturable periprosthetic infection, if the microbiological processing is adequate.

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Increasing incidence of midterm and long-term complications after endovascular graft repair of abdominal aortic aneurysms: a note of caution based on a 9-year experience.

OBJECTIVE: To analyze the late complications after endovascular graft repair of elective abdominal aortic aneurysms (AAAs) at the authors' institution since November 1992. SUMMARY BACKGROUND DATA: Recently, the use of endovascular grafts for the treatment of AAAs has increased dramatically. However, there is little midterm or long-term proof of their efficacy. METHODS: During the past 9 years, 239 endovascular graft repairs were performed for nonruptured AAAs, many (86%) in high-risk patients or in those with complex anatomy. The grafts used were Montefiore (n = 97), Ancure/EVT (n = 14), Vanguard (n = 16), Talent (n = 47), Excluder (n = 20), AneuRx (n = 29), and Zenith (n = 16). All but the AneuRx and Ancure repairs were performed as part of a U.S. phase 1 or phase 2 clinical trial under a Food and Drug Administration investigational device exemption. Procedural outcomes and follow-up results were prospectively recorded. RESULTS: The major complication and death rates within 30 days of endovascular graft repair were 17.6% and 8.5%, respectively. The technical success rate with complete AAA exclusion was 88.7%. During follow-up to 75 months (mean +/- standard deviation, 15.7 +/- 6.3 months), 53 patients (22%) died of unrelated causes. Two AAAs treated with endovascular grafts ruptured and were surgically repaired, with one death. Other late complications included type 1 endoleak (n = 7), aortoduodenal fistula (n = 2), graft thrombosis/stenosis (n = 7), limb separation or fabric tear with a subsequent type 3 endoleak (n = 1), and a persistent type 2 endoleak (n = 13). Secondary intervention or surgery was required in 23 patients (10%). These included deployment of a second graft (n = 4), open AAA repair (n = 5), coil embolization (n = 6), extraanatomic bypass (n = 4), and stent placement (n = 3). CONCLUSION: With longer follow-up, complications occurred with increasing frequency. Although most could be managed with some form of endovascular reintervention, some complications resulted in a high death rate. Although endovascular graft repair is less invasive and sometimes effective in the long term, it is often not a definitive procedure. These findings mandate long-term surveillance and prospective studies to prove the effectiveness of endovascular graft repair.

Aged↗

Prevention and management of complications associated with the hydroxyapatite implant.

The hydroxyapatite orbital implant offers many advantages compared to conventional implants; however, its use is not entirely free of complications. The objectives of this study are to review the complications encountered with the hydroxyapatite orbital implant, suggest mechanisms contributing to the development of these complications, and emphasize aspects of surgical technique that will minimize the risk of the most frequent complication, implant exposure. Preoperative, operative, and postoperative records of 154 patients receiving primary and secondary hydroxyapatite implants were studied retrospectively. Three clinical types of exposure defects were observed; dehiscences along the horizontal suture line, defects over holes in the hydroxyapatite, and a defect adjacent to the site of radiation plaque therapy. Most small exposures healed spontaneously. Medium and large defects were associated with anteriorly malpositioned implants, most often required surgical intervention, and were successfully managed with one or a combination of techniques including flaps, mucous membrane grafts, or repositioning of the implant more posteriorly. Placing the hydroxyapatite implant as far posteriorly as possible and advancing the extraocular muscles 3-5 mm from the apex of the implant will prevent most exposures. Unlike other types of implants, the hydroxyapatite implant does not migrate or extrude, and when exposed, usually does not require removal.

Adolescent↗

Twenty-year results of McKee-Farrar versus Charnley prosthesis.

The results of 107 consecutive McKee-Farrar and 70 Charnley total hip arthroplasties performed in 169 patients between 1975 and 1976 are reviewed. At an average followup of 20 years (range, 19-21 years), 29 patients with 20 McKee-Farrar and 11 Charnley prostheses were available for clinical and radiologic evaluation; 102 patients (107 hips) had died, 3 patients were lost to followup, and 5 patients (6 hips) were unavailable for review because of medical problems. There were 5 revisions for sepsis and 1 Girdlestone procedure for recurrent dislocation. Sixteen McKee-Farrar and 8 Charnley prostheses were revised for aseptic loosening, giving a 20-year aseptic probability of survival of 77% and 73%, respectively. Radiographic signs of loosening were present in 52% of the surviving prostheses. Clinical scores showed weak correlation with the radiographic loosening in both groups, and 18 McKee-Farrar and 8 Charnley prostheses were still considered satisfactory by the patients. The mean annual linear polyethylene wear was 0.12 mm. Osteolytic lesions were observed in association with 2 McKee-Farrar and 5 Charnley prostheses in surviving hips. The long term results of the McKee-Farrar prosthesis are comparable with those of the low friction arthroplasty in this series. Wear of the polyethylene bearing and accumulation of polyethylene particles in the periprosthetic tissue may become an increasing problem. Second generation all metal implants seem to be worth considering in patients with long life expectancy.

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Aspiration of the knee joint before revision arthroplasty.

Sixty-four operative procedures were performed on 55 patients with knee arthroplasties for pain, loosening, instability, or suspicion of infection. Forty-three knees had a preoperative aspiration. In 19 knees, the aspiration showed growth on solid media, and in 18 of these knees the diagnosis of infection was confirmed by the intraoperative cultures. In 1 knee with an infected total knee replacement, the patient was receiving an intravenous antibiotic at the time of arthroscopic irrigation and debridement and the cultures showed no growth. In 23 of 24 knees with a negative preoperative aspiration, the intraoperative cultures showed no growth on solid media. In 1 knee with a preoperative aspiration that had negative results, a single intraoperative culture grew Staphylococcus epidermidis. However, the presenting symptoms, examination, preoperative radiographs, and intraoperative evaluation were consistent with aseptic loosening of a cemented total knee arthroplasty. Thus, the preoperative aspiration of the prosthetic knee joint had a sensitivity of 100%, specificity of 100%, and accuracy of 100%. The Westergren erythrocyte sedimentation rate, peripheral leukocyte count, and presenting symptoms correlated poorly with infection. Radiographs were also not helpful in the diagnosis of infection, with loosening of components, periostitis, focal osteolysis, and radiolucent lines frequently seen in infected and noninfected knees. Preoperative aspiration of the knee is the most helpful study for the diagnosis or exclusion of infection in a prosthetic knee joint.

Adult↗