1,720,977 research outputs found
What was the survival of megaprostheses in lower limb reconstructions after tumor resections?
Get PDFAnalisi retrospettiva delle ricostruzioni dell'arto inferiore con protesi modulariBackground: Prosthetic replacement is the most commonly used option for reconstruction of osteoarticular bone loss resulting from bone neoplasm resection or prosthetic failure. Starting in late 2001, we began exclusively using a single system for large-segment osteoarticular reconstruction after tumor resection; to our knowledge, there are no published series from one center evaluating the use of this implant.
Questions/purposes: We investigated the following issues: (1) What is the overall survival, excluding local tumor recurrence, for these endoprostheses used for tumor reconstructions of the lower extremities (knee and hip)? (2) What types of failure were observed in these reconstructions? (3) Do the survival and complications vary according to site of implant?
Methods: Between September 2001 and March 2012, we exclusively used this implant for tumor reconstructions. During that time, 278 patients underwent tumor reconstructions of the hip or knee, of whom 200 (72%) were available at a minimum 2 years followup. Seventy-eight patients were excluded from the study for insufficient followup as a result of early death (42) or loss at followup (36). The reconstruction types were the following: proximal femur (69 cases), distal femur (87), proximal tibia (32), and total knee (12). Failures were classified according to the Henderson classification. Nine patients among those with followup shorter than 2 years had presented one or more failures and they were included in our analysis but separately evaluated.
Results: Overall survival (no further surgical procedures of any type after primary surgery), excluding Type 5 failure (tumor recurrence), was 75.9% at 5 years and 66.2% at 10 years. Seventy-one failures occurred in 58 implants (29%). Mechanical failures accounted for 59.2% and nonmechanical failures for 40.8%. The first causes of failure of the implants were the result of soft tissue failure in 6%, aseptic loosening in 3%, structural failure in 7%, infection in 8.5%, and tumor recurrence in 4.5% of the whole series. Nine implants sustained two or more failures. Overall incidence of infection was 9.5%. No statistically significant differences were observed according to anatomical site.
Conclusions: Like in the case with many such complex oncologic reconstructions, the failure rate at short- to midterm in this group was over 20%. Comparative trials are called for to ascertain whether one implant is superior to another. Infection and structural failure were the most frequent modes of failure in our experience.
Level of Evidence: Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence
Levels of silver ions in body fluids and clinical results in silver-coated megaprostheses after tumour, trauma or failed arthroplasty
Get PDFIntroduction: Infection in megaprostheses remains an unsolved problem, with a rate of occurrence ranging from 5% to 12%. Silver coating of medical devices has recently been proposed to reduce infection rate because of the antibacterial effect of silver. This innovation could be particularly interesting for megaprostheses, but few data have been reported in the literature. Materials and methods: From June 2010 to August 2014 a modified MegaC System megaprosthesis with an innovative peripheral silver-added layer of titanium alloy ('Porag') was implanted in 33 patients after previous infection (21 patients) or at high risk for infection because of local or general conditions (12 patients). Previous infection followed megaprosthesis or standard arthroplasty procedures in 14 patients and trauma surgery in seven patients. A proximal femur replacement was performed in 13 patients, distal femur replacement in 13, total femur in one, and knee arthrodesis in six. Clinical results and levels of silver in blood, urine and wound drains were examined. Results: Minimum follow-up of the patients was one year (average 25.9 months).There was no infection during the first two years after surgery in the 12 patients who received a silver-coated megaprosthesis and had no previous history of infection. An infection developed in one patient at 25 months after surgery following two further surgical procedures.Infection recurred at seven months and 24 months in two out of the 21 patients (9.5%) who had received the implant because of previous septic complications.There was no clinical evidence of argyria, and no local or systemic side effects related to silver were detected.Mean levels of silver ranging from 0.41 to 5.33. μg/L in blood and from 0.28 to 0.86. μg/L in urine were detected at 24. h to 36 months after surgery. Conclusions: Silver-coated megaprostheses showed promising results in this series in terms of prevention of infection in a high-risk group of patients, many of whom had a history of infection. No side-effects were detected. The circulating silver levels confirm both the persistence of silver-coating activity after three years and the safety of silver-coated implants. Longer follow-up and larger series are needed
Is Arthrodesis a Reliable Salvage Option following Two-Stage Revision for Suspected Infection in Proximal Tibial Replacements? A Multi-Institutional Study
No full textThe aim of this multicentric retrospective study was to verify whether knee arthrodesis (KA) is a viable reconstructive option after two-stage revision for infection of proximal tibia (PT) endoprosthetic reconstruction (EPR). Sixty patients who underwent a two-stage revision were included. Definitive EPR or a KA with a modular system was performed following consideration of soft tissue and extensor mechanism conditions. Patients were evaluated with Musculoskeletal Tumor Society Score and Oxford Knee Score. Implant survival was assessed on the basis of recurrence of infection. Five patients did not receive any reconstruction after the first stage. In 14 cases, a KA was performed, and in 41, an EPR was implanted. At 5 years follow-up, reinfection rate in the KA group was lower (10 vs. 17.5% in KA and EPR groups, respectively). In reinfected patients, the KA group had a reduced rate of amputation when compared with those with EPR (50 vs. 88%). Functional evaluation did not show any significant differences between the two groups. A successful KA using a modular implant can eradicate infection and allow preservation of the limb with good function and good pain relief in after two-stage revision for an infected PT EPR
Soft tissue myxofibrosarcoma: A clinico-pathological analysis of a series of 75 patients with emphasis on the epithelioid variant
No full textBackground and Objectives: The clinical course of soft tissue myxofibrosarcoma is characterized by a high incidence of recurrences and there is no agreement on how to identify patients at major risk. An epithelioid histological variant has been described, with a possible worse prognosis. We reviewed our series to identify prognostic factors and assess clinical significance of the epithelioid variant. Methods: We examined the clinico-pathological features of a series of 75 patients affected by soft tissue myxofibrosarcoma at a mean follow-up of 63 months (range 17-132). Results: Disease specific survival and local recurrence free survival were, respectively, 84.8% and 76.8% at 5 years. Seven patients (8.6%) presented with the epithelioid variant with a survival of 62.5%. High grade and epithelioid morphology were negative prognostic factors for patient survival, high grade, and inadequate surgical margins for local recurrence. Radiotherapy had a local protective effect in high grade tumors. Conclusions: Our experience confirms the difficulties in obtaining wide margins in myxofibrosarcoma and the high rate of recurrence. Local recurrences did not significantly affect survival and a limb-sparing approach can be chosen also in recurrences. Patients affected by the epithelioid variant showed a worse prognosis. Chemotherapy should be considered as adjuvant treatment in this subtype
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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