The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Kotaro Nishida - One of the best experts on this subject based on the ideXlab platform.
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c1 laminectomy for retro odontoid Pseudotumor without atlantoaxial subluxation review of seven consecutive cases
European Spine Journal, 2013Co-Authors: Kenichiro Kakutani, Minoru Doita, Masaho Yoshikawa, Norihide Sha, Masahiro Kurosaka, Koichiro Maeno, Takashi Yurube, Kotaro NishidaAbstract:Purpose A retro-odontoid Pseudotumor is usually a reactive fibrocartilaginous mass associated with atlantoaxial subluxation (AAS). However, a retro-odontoid Pseudotumor not associated with AAS, which undergoes spontaneous regression following C1 laminoplasty, has been reported. The purpose of this study was to report surgical outcomes of C1 laminectomy for retro-odontoid Pseudotumor without AAS.
Donald S Garbuz - One of the best experts on this subject based on the ideXlab platform.
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prevalence of Pseudotumor in asymptomatic patients after metal on metal hip arthroplasty
Journal of Bone and Joint Surgery American Volume, 2011Co-Authors: Daniel H Williams, Nelson V Greidanus, Bassam A Masri, Clive P Duncan, Donald S GarbuzAbstract:Background: The cause of recently reported Pseudotumor formation in patients with metal-on-metal hip replacements is unknown. It has been postulated that there is an association between elevated levels of serum metal ions and Pseudotumor formation. The primary purpose of this study was to assess the prevalence of Pseudotumor formation in asymptomatic patients with a metal-on-metal total hip replacement after a minimum duration of follow-up of two years. A secondary purpose was to assess whether a correlation exists between elevated serum metal ion levels and Pseudotumor formation. Methods: In the present study, the prevalence of Pseudotumor formation, as detected with ultrasound, was evaluated for thirty-one asymptomatic patients with a metal-on-metal total hip arthroplasty, twenty-four asymptomatic patients with a metal-on-polyethylene total hip arthroplasty, and twenty asymptomatic patients with a metal-on-metal hip resurfacing arthroplasty. Serum levels of cobalt and chromium were measured in the metal-on-metal total hip arthroplasty and hip resurfacing arthroplasty groups. Results: Ten patients (32%) in the metal-on-metal total hip arthroplasty group had a solid or cystic mass, with another three patients (10%) having a substantial fluid collection. Five patients (25%) in the hip resurfacing arthroplasty group had a solid or cystic mass, with another patient (5%) having a fluid collection. Pseudotumor formation was significantly more frequent in the metal-on-metal total hip arthroplasty group compared with the metal-on-polyethylene total hip arthroplasty group (p = 0.015). We did not detect a significant correlation between the serum metal ion levels and the size of Pseudotumor abnormality. The median serum metal ion level was greater in patients with Pseudotumor formation than it was in those without Pseudotumor formation, but the difference was not significant. Conclusions: We recommend high-resolution ultrasound surveillance of all asymptomatic patients with a metal-on-metal implant that is known to result in high serum metal ion levels. Once a metal-on-metal implant is known to be associated with high serum metal ions, the measurement of ion levels does not helpfully contribute to surveillance. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.
John Antoniou - One of the best experts on this subject based on the ideXlab platform.
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inflammatory Pseudotumor complicating metal on highly cross linked polyethylene total hip arthroplasty
Journal of Arthroplasty, 2012Co-Authors: Alan J Walsh, Vassilios S Nikolaou, John AntoniouAbstract:Inflammatory masses or cysts occurring in the pelvis, thigh, and gluteal regions, often mimicking infection, occasionally arise after total hip arthroplasty procedures. Inflammatory Pseudotumors comprise a subgroup of these lesions. Pseudotumors have been associated with pain, rashes, instability, neuropathy, and premature loosening of prosthetic components, often leading to early and difficult revision surgery. The association between such Pseudotumors and metal-on-metal bearings has led to questions regarding the performance of these bearings in hip arthroplasty. We present a case of Pseudotumor requiring revision surgery, which occurred uniquely around a metal-on-highly cross-linked polyethylene bearing.
D W Murray - One of the best experts on this subject based on the ideXlab platform.
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the in vivo linear and volumetric wear of hip resurfacing implants revised for Pseudotumor
Journal of Bone and Joint Surgery American Volume, 2011Co-Authors: S Glynjones, Anne Roques, A Taylor, Youngmin Kwon, P Mclardysmith, H S Gill, William L Walter, M A Tuke, D W MurrayAbstract:Background: Metal-on-metal arthroplasty-related Pseudotumors can cause severe local destruction of bone and soft tissues. The cause of Pseudotumors is unknown, although some authors have implicated metal wear debris. The aim of this study was to measure the location and magnitude of wear on resurfacing devices that were retrieved during revision procedures for Pseudotumor (the Pseudotumor group) and for other reasons (the control group). Methods: We examined thirty-six hip-resurfacing implants, which were divided into two groups: eighteen implants from patients with a diagnosis of Pseudotumor and eighteen control implants. Implant orientation and patient demographics were recorded. Three-dimensional, contactless metrology was used to scan the surface of the femoral and acetabular components to a resolution of 20 nm. Linear and volumetric wear were measured, and the components were examined for evidence of edge wear. Results: There was three times more total linear wear and over six times more total volumetric wear of the femoral and acetabular components in the Pseudotumor group as compared with that in the control group. The mean linear wear rate and standard deviation of the femoral components in the Pseudotumor group (8.4 ± 8.7 μm/yr) were significantly greater than those in the control group (2.9 ± 3.9 μm/yr; p = 0.01). The mean volumetric wear rate of the femoral components was also significantly greater in the Pseudotumor group (3.3 ± 5.7 mm3/yr) than it was in the control group (0.8 ± 1.2 mm3/yr; p = 0.009). Seventeen of eighteen subjects in the Pseudotumor group had edge wear, compared with six of eighteen in the control group (p < 0.001). Conclusions: Implants that were retrieved because of Pseudotumor had a significantly higher wear rate and prevalence of edge wear than the control implants did. There was a strong association between Pseudotumor and the high levels of wear debris that are generated during edge-loading. However, not all patients with high wear developed Pseudotumors, and not all Pseudotumors had high wear; therefore, other factors are most likely involved in the cause of Pseudotumors. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
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characterization of metal wear nanoparticles in Pseudotumor following metal on metal hip resurfacing
Nanomedicine: Nanotechnology Biology and Medicine, 2011Co-Authors: Youngmin Kwon, Zhidao Xia, Shahid Mehmood, Clive Downing, Kerstin Jurkschat, D W MurrayAbstract:Abstract Biopsies from a typical case of Pseudotumor following metal-on-metal hip resurfacing (MoMHR) were analyzed using light and transmission electron microscopy, backscatter scanning electron microscopy and energy dispersive x-ray spectrometry (EDS). Heavy macrophage infiltration was observed in all black pigmented specimens. Metal nanoparticles (NPs) were observed exclusively within phagosomes of living macrophages and fragments of dead macrophages. Although dead fibroblasts were found to be juxtaposed with dead and disintegrated macrophages, the NPs were not seen within either live or dead fibroblasts. Chromium (Cr) but not cobalt (Co) was the predominant component of the remaining wear NPs in tissue. The current study finding suggests that corrosion of Co in phagosomes of macrophages and resultant Co ion release lead to tissue necrosis and adverse soft tissue reactions (Pseudotumors). Further studies are required to elucidate the precise mechanism of intracellular corrosion of metal NPs and the long-term toxicity of the Cr remaining in the peri-prosthetic tissues. From the Clinical Editor In this study of metal-on-metal hip resurfacing-related tissue necrosis and Pseudotumor formation, corrosion and decomposition of metallic cobalt in phagosomes of macrophages and resultant cobalt ion release were demonstrated to be the key elements of pathogenesis.
Grant T Liu - One of the best experts on this subject based on the ideXlab platform.
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overweight and obesity in pediatric secondary Pseudotumor cerebri syndrome
American Journal of Ophthalmology, 2015Co-Authors: Grace L Paley, Claire A Sheldon, Evanette Burrows, Marianne Chilutti, Grant T LiuAbstract:Purpose To examine the clinical, demographic, and anthropometric patient characteristics of secondary Pseudotumor cerebri syndrome in children and adolescents based on the recently revised diagnostic criteria. Design Retrospective observational case series. Methods Patients seen at a tertiary children’s hospital for Pseudotumor cerebri syndrome were classified as having either primary idiopathic (n = 59) or secondary Pseudotumor cerebri syndrome (n = 16), as rigorously defined by recently revised diagnostic criteria. Outcomes included body mass index Z-scores (BMI-Z), height and weight Z-scores, demographics, and clinical features at presentation, such as headache, sixth nerve palsy, and cerebrospinal fluid (CSF) opening pressure. Results In this cohort, the associated conditions and exposures seen in definite secondary Pseudotumor cerebri syndrome included tetracycline-class antibiotics (n = 11), chronic kidney disease (n = 3), withdrawal from chronic glucocorticoids (n = 1), and lithium (n = 1). Other associations observed in the possible secondary Pseudotumor cerebri syndrome group included Down syndrome, vitamin A derivatives, and growth hormone. In comparison with primary Pseudotumor cerebri syndrome, definite secondary Pseudotumor cerebri syndrome patients were on average older (15.0 vs 11.6 years; P = .003, Mann-Whitney test). According to US Centers for Disease Control (CDC) classifications, 79% of children with secondary Pseudotumor cerebri syndrome were either overweight or obese (36% overweight [n = 5] and 43% obese [n = 6]), as compared to 32% nationally. Conclusions Even when a potential inciting exposure is identified for pediatric Pseudotumor cerebri syndrome, the possible contribution of overweight and obesity should be considered.
