1,721,256 research outputs found
Magnetic resonance imaging–assessed subchondral cysts and incident knee pain and knee osteoarthritis: data from the Multicenter Osteoarthritis Study
Get PDFObjective
To examine whether knee subchondral cysts, measured on magnetic resonance imaging (MRI), are associated with incident knee osteoarthritis (OA) outcomes.
Methods
We used longitudinal data from the Multicenter Osteoarthritis Study, a community-based cohort of subjects with risk factors for knee OA. Participants without a history of knee surgery and/or inflammatory arthritis (i.e., rheumatoid arthritis and gout) were followed up for 84 months for the following incident outcomes: 1) radiographic knee OA (Kellgren/Lawrence grade ≥2), 2) symptomatic radiographic knee OA (radiographic knee OA and frequent knee pain), and 3) frequent knee pain (with or without radiographic knee OA). In a subset of participants, subchondral cysts were scored on baseline MRIs of 1 knee. Multiple logistic regression, with adjustment for participant characteristics and other baseline knee MRI findings, was used to assess whether subchondral cysts were predictive of incident outcomes.
Results
Among the participants with knees eligible for analyses of outcomes over 84 months, incident radiographic knee OA occurred in 22.8% of knees with no baseline radiographic knee OA, symptomatic radiographic knee OA occurred in 17.0% of knees with no baseline symptomatic radiographic knee OA, and frequent knee pain (with or without radiographic knee OA) occurred in 28.8% of knees with no baseline radiographic knee OA and 43.7% of knees with baseline radiographic knee OA. With adjustment for age, sex, and body mass index, the presence of subchondral cysts was not associated with incident radiographic knee OA but was associated with increased odds of incident symptomatic radiographic knee OA (odds ratio 1.92 [95% confidence interval 1.16–3.19]) and increased odds of incident frequent knee pain in those who had radiographic knee OA at baseline (odds ratio 2.11 [95% confidence interval 0.87–5.12]). Stronger and significant associations were observed for outcomes based on consistent reports of frequent knee pain within ~1 month of the study visit.
Conclusions
Subchondral cysts are likely to be a secondary phenomenon, rather than a primary trigger, of radiographic knee OA, and may predict symptoms in knees with existing disease
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
Knee joint kinematics before and after body weight change
Get PDFObesity is a well-defined mechanical factor for osteoarthritis (OA). More than one-third of adults in the United States are obese, and one in three obese adults has arthritis. In obese individuals, knee pain is highly prevalent and is often thought to be the first symptom of knee OA. In the pathomechanics of knee OA, altered kinematics and contact location in the knee joint are potent contributors to OA initiation and progression. However, such kinematics and cartilage contact location in obese individuals, and how the knee joint responses to excess load due to obesity are not clear and understudied, mainly limited by the instrumentations. Therefore, we conducted a series of dissertation studies to investigate the effect of weight on the knee joint kinematics in six degrees of freedom (6DOF) and cartilage contact location using a fluoroscopic imaging system with magnetic resonance-based morphological models. In Study 1, the 6DOF kinematic analysis showed that obese individuals with knee pain walked with a reduced range of flexion-extension motion and a reduced medial-lateral translation compared with non-obese controls. In Study 2, the cartilage contact analysis showed that obese individuals experienced different contact location on both the tibial and femoral cartilage surfaces during walking when compared with a healthy group, while pain had a minimal effect on the cartilage contact location. In Study 3, we followed up with the obese individuals in Study 1 and the kinematic analysis showed that the change in range of the flexion-extension and adduction-abduction motion during gait were associated with the change in body weight; however, knee pain was not associated with the kinematic change. In conclusion, this series of dissertation studies suggests that the kinematics of the knee in obese individuals with knee pain was modifiable through weight loss. Weight management should be addressed more than controlling for pain in obese individuals with pain, as pain management might not able to restore the contact locations.2020-07-06T00:00:00
Correlates and consequences of varus knee thrust in osteoarthritis
Get PDFVarus knee thrust is an abnormal frontal-plane movement (i.e., an out-bowing) of the knee that occurs during the weight-acceptance phase of gait. Varus thrust is of clinical interest, as it is a potentially-modifiable biomechanical risk factor for knee osteoarthritis (OA) progression and has been associated with knee pain. The overall aim of this dissertation is to identify the structural and symptomatic consequences of varus thrust at the knee and along the lower limb, and the possible anatomical and sensorimotor causes of varus thrust in older adults with or at risk for OA. Varus thrust was assessed in Multicenter Osteoarthritis (MOST) Study participants using high-speed videos of self-paced walking. Varus thrust was observed in 31.3% of 3730 knees. We investigated the longitudinal relation of varus thrust to MRI lesions and found that thrust was associated with increased odds of incident and worsening bone marrow lesions and worsening cartilage loss. We then investigated the longitudinal association of varus thrust with WOMAC knee pain and found that thrust was associated with increased odds of incident and worsening total WOMAC knee pain and worsening pain during weight-bearing and non-weight bearing activities. In an ancillary quantitative gait analysis of a single subject with unilateral varus thrust, we found altered joint moments at the hip, knee, and ankle in the thrust limb compared to the non-thrust limb. We bolstered this pilot data with an investigation of low back and lower extremity pain in the presence of thrust in MOST participants: limbs with thrust had increased odds of incident frequent pain proximal (hip or low back) and distal (ankle and foot) to the knee compared to limbs without thrust. Finally, we investigated the cross-sectional relation of anatomical and sensorimotor impairments at the knee and lower extremity to the prevalence of varus thrust. Thrust was most prevalent in limbs with static varus malalignment and supinated feet during gait, while increasing static knee laxity had a protective effect against thrust. These results fill substantial gaps in the narrative regarding the role of varus thrust in OA development
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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