1,720,960 research outputs found
Computer assisted surgery and 3d printing in orthopaedic oncology: A lesson learned by cranio-maxillo-facial surgery
Get PDFPrimary bone sarcomas are rare tumors and surgical resection in combination with chemo and radiation therapy is the mainstay of treatment. Some specific anatomical sites still represent a reconstructive challenge due to their complex three-dimensional anatomy. In recent years, patient specific instruments along with 3D printing technology has come to represent innovative techniques in orthopaedic oncology. We retrospectively reviewed 23 patients affected by primary bone sarcoma treated with patient-specific instruments and 3D printing custom made prostheses. At follow up after approximately two years, the infection rate was 26%, mechanical complication rate 13%, and local recurrence rate 13% (with a five-years implant survival rate of 74%). Based on our experience, patient-specific instruments and 3D custom-made prostheses represents a reliable and safe technique for improving the accuracy of resection of primary bone tumour, with a particular use in pelvic surgery ameliorating functional results
3D Surgical Planning for Customized Devices in Orthopaedics: Applications in Massive Hip Reconstructions of Oncological Patients
Get PDFThis study investigates the morphological impact of using three-dimensional (3D) printed custom implants in surgical hip reconstruction compared to the conventional bone graft and standard size implant methods. An amount of 16 patients at the Rizzoli Orthopaedic Institute who underwent hip reconstruction surgery for tumors involving the P2 pelvis region were selected using stratified sampling. Half of them were randomly selected to receive 3D-printed implants, and the other half were selected to receive standard implants with bone grafts. Six months post-surgery, computed tomography (CT) scans were used to identify the hip joint center of rotation and to measure greater the trochanter offset and acetabular inclination angle. These CT scans were also used to construct a 3D model of the pelvis for 3D measurements. The results show no significant differences in accuracy, using Student’s t-test and Mann–Whitney U-test (p-value > 0.05), between the two methods for reconstructing the hip joint center of rotation or greater trochanter offset. However, 3D-printed implants showed statistically significant greater precision, using Student’s t-test (p-value < 0.05), in reconstructing the acetabular inclination angle compared to the conventional bone graft and standard-sized off-the-shelf implants. This superior precision reduces the risk of impingement of the femur implant neck with the acetabulum implant cup, which directly relates to improved implant survivorship. These findings support the continued exploration of 3D printing technology for personalized orthopedic solutions
Bone Infarct-Associated Osteosarcoma: Epidemiologic and Survival Trends
No full textBackground: Bone tumors are not a frequent occurrence and bone infarct-associated sarcomas are even rarer. The prognosis of patients experiencing this disease is poor and treatment for them remains a challenge. Nevertheless, hardly any analyses in literature report on secondary osteosarcoma (SO) on bone infarct and most of the data available do not provide sufficient details. We evaluated whether this condition could be further characterized and if prognosis could be influenced by the chemotherapy (ChT) treatment. We sought to determine: (1) the main features of this rare disease; (2) the overall survival (OS) rate; (3) the OS rate associated to ChT treatment; and (4) the correspondence between our results and published data in terms of survival. Methods: We retrospectively reviewed patients admitted at the Rizzoli Orthopedic Institute of Bologna between 1992 and 2018 (1,465 total cases of osteosarcoma). We identified a list of 11 cases of SO on bone infarct (cohort 1). We conferred about the epidemiology, surgical and ChT treatment, and surveillance of infarct-associated osteosarcoma showing the correlation to data present in literature, corresponding to 14 case reports published within 1962-2018 (cohort 2). Results: (1) Cohort 1 was made of 11 patients: six females and five males, median age was 55 years. Nine (81%) were grade 4 and two (19%) were grade 3. Tumor predominantly arose on distal femur (64%). Most of patients had localized osteosarcoma at the diagnosis (81%); resection surgery was the elective treatment (73%) followed by amputation (18%). Of 11 patients, seven received also ChT (64%). (2) Five-year OS was 62% (95% confidence interval [CI]: 28-84). Median OS was 74 months (95% CI: 12-not reached). The cumulative incidence of cancer-related deaths (CICRD) was 37.7% (95% CI: 11.4-64.5) at 120 months. (3) In the group treated with only surgery, OS was 50% at 5 years. For patients treated with any form of ChT, OS was 71% at 5 years (p = 0.4773) and hazard ratio (HR) 0.56. The CICRD was 29% (at 2 years of follow-up. Instead, it was of 50% for patients treated only with surgery. (4) Median survival was 74 months and 12 months for cohort 1 and cohort 2, respectively (p = 0.0247). Data analysis showed a decreased HR for cohort 1 compared to cohort 2 (HR 0.315). Results confirmed also stratifying for age and ChT administration (HR 0.333). Conclusions: Based on this work, our opinion is that the treatment of SO patients with ChT combined to surgery improves patients' survival
A Pelvic Reconstruction Procedure for Custom‐Made Prosthesis Design of Bone Tumor Surgical Treatments
Get PDFIn orthopaedic oncology, limb salvage procedures are becoming more frequent thanks to recent major improvements in medical imaging, biomechanical modelling and additive manufacturing. For the pelvis, surgical reconstruction with metal implants after tumor resection remains challenging, because of the complex anatomical structures involved. The aim of the present work is to define a consistent overall procedure to guide surgeons and bioengineers for proper implant design. All relevant steps from medical imaging to an accurate 3D anatomical‐based model are here reported. In detail, the anatomical 3D models include bone shapes from CT on the entire pelvic bone, i.e., including both affected and unaffected sides, and position and extension of the tumor and soft tissues from MRI on the affected side. These models are then registered in space, and an initial shape of the personalized implant for the affected side can be properly designed and dimensioned based on the information from the unaffected side. This reported procedure can be fundamental also for virtual pre‐surgical planning, and the design of patient‐specific cutting guides, which would result is a safe margin for tumor cut. The entire procedure is here shown by describing the results in a single real case
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
Biomarkers of bone healing induced by a regenerative approach based on expanded bone marrow–derived mesenchymal stromal cells
No full textBackground: Safety and feasibility of a regenerative strategy based on the use of culture-expanded mesenchymal stromal cells (MSCs) have been investigated in phase 2 trials for the treatment of nonunion and osteonecrosis of the femoral head (ONFH). As part of the clinical study, we aimed to evaluate if bone turnover markers (BTMs) could be useful for predicting the regenerative ability of the cell therapy product. Materials and Methods: The bone defects of 39 patients (nonunion: n = 26; ONFH: n = 13) were treated with bone marrow - derived MSCs, expanded using a clinical-grade protocol and combined with biphasic calcium phosphate before implantation. Bone formation markers, bone-resorption markers and osteoclast regulatory proteins were measured before treatment (baseline) and after 12 and 24 weeks from surgery. At the same time-points, clinical and radiological controls were performed to evaluate the bone-healing progression. Results: We found that C-Propeptide of Type I Procollagen (CICP) and C-terminal telopeptide of type-I collagen (CTX) varied significantly, not only over time, but also according to clinical results. In patients with a good outcome, CICP increased and CTX decreased, and this trend was observed in both nonunion and ONFH. Moreover, collagen biomarkers were able to discriminate healed patients from non-responsive patients with a good diagnostic accuracy. Discussion: CICP and CTX could be valuable biomarkers for monitoring and predicting the regenerative ability of cell products used to stimulate the repair of refractory bone diseases. To be translated in a clinical setting, these results are under validation in a currently ongoing phase 3 clinical trial
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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