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Osteoarthritis (OA) is characterized by cartilage degeneration and destruction, leading to joint ankylosis and disability. The major challenge in diagnosing OA at early stage is not only lack of clinical symptoms but also the insufficient histological and immunohistochemical signs. Alteration in cartilage stiffness during OA progression, especially at OA initiation, has been confirmed by growing evidences. Moreover, the stiffness of cartilage extracellular matrix (ECM), pericellular matrix (PCM) and chondrocytes during OA development are dynamically changed in unique and distinct fashions, revealing possibly inconsistent conclusions when detecting cartilage matrix stiffness at different locations and scales. In addition, it will be discussed regarding the mechanisms through which OA-related cartilage degenerations exhibit stiffened or softened matrix, highlighting some critical events that generally incurred to cartilage stiffness alteration, as well as some typical molecules that participated in constituting the mechanical properties of cartilage. Finally, in vitro culturing chondrocytes in various stiffness-tunable scaffolds provided a reliable method to explore the matrix stiffness-dependent modulation of chondrocyte metabolism, which offers valuable information on optimizing implant scaffolds to maximally promote cartilage repair and regeneration during OA. Overall, this review systematically and comprehensively elucidated the current progresses in the relationship between cartilage stiffness alteration and OA progression. We hope that deeper attention and understanding in this researching field will not only develop more innovative methods in OA early detection and diagnose but also provide promising ideas in OA therapy and prognosis., (© 2024 The Author(s).)

Objective: CircRNA circCTNNA1 has been characterized as a critical player in cancer biology, while its role in other human diseases is unknown. This study was carried out to study the role of circCTNNA1 in osteoarthritis (OA)., Materials and Methods: RNA was extracted from synovial fluid samples donated by OA patients ( n  = 62). RT-qPCRs were then performed to determine the expression of circCTNNA1 and miR-29a in these synovial fluid samples. The interaction between circCTNNA1 and miR-29a was predicted using an online program IntaRNA 2.0 and confirmed by RNA pull-down assay. Overexpression of circCTNNA1 and miR-29a was achieved in synoviocytes to analyze their effects on each other's expression. The role of circCTNNA1 and miR-29a in regulating synoviocyte apoptosis was explored by cell apoptosis assay., Results: CircCTNNA1 was downregulated in OA, while miR-29a was overexpressed in OA. CircCTNNA1 and miR-29a were not significantly correlated. RNA pull-down assay illustrated the direct interaction between circCTNNA1 and miR-29a. In synoviocytes, overexpression of circCTNNA1 and miR-29a failed to regulate the expression of each other. CircCTNNA1 overexpression suppressed the enhancing effects of miR-29a overexpression on cell apoptosis induced by LPS., Conclusions: CircCTNNA1 is downregulated in OA, and its overexpression suppresses synoviocyte apoptosis via sponging miR-29a.

Objective: To investigate the relationship between sedentary behavior and quality-adjusted life years (QALYs) among participants in the Osteoarthritis Initiative., Design: Longitudinal, observational design., Setting: Osteoarthritis Initiative cohort., Participants: Individuals (N=1794) from a prospective, multicenter longitudinal cohort were classified into quantile groups based on average daily sedentary time (most sedentary, quartile 1 [Q1] ≥11.6h; 10.7h≤ Q2 <11.6h; 9.7h≤ Q3 <10.7h; least sedentary, Q4 <9.7h)., Interventions: Not applicable., Main Outcome Measures: Individual QALYs were estimated over 2 years from the area under the curve of health-related utility scores derived from the Medical Outcomes Study 12-Item Short-Form Health Survey versus time. The relationship between baseline sedentary behavior and median 2-year QALYs was estimated using quantile regression adjusted for socioeconomic factors and body mass index., Results: Lower QALYs over 2 years were more frequently found among the most sedentary (Q1, median 1.59), and QALYs increased as time spent in baseline sedentary behavior decreased (median QALYs for Q2, 1.64; Q3, 1.65; Q4, 1.65). The relationship of sedentary time and median QALY change was only significant for the most sedentary Q1 group, where an additional hour of sedentary behavior significantly reduced QALYs by -.072 (95% confidence interval, -.121 to -.020)., Conclusions: Our findings suggest that individuals with the most extreme sedentary profiles may be vulnerable to additional losses of quality of life if they become more sedentary. Targeting these individuals to decrease sedentary behavior has the potential to be cost-effective., (Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Objective: To examine the correlation between hip-knee-ankle and femur-tibia radiograph angles, calculate the offset of the femur-tibia angle with respect to the hip-knee-ankle angle, calculate the sensitivity and specificity and area under the receiver operating characteristic (ROC) curve of the femur-tibia angle, and examine the relationship of malalignment by each approach with osteoarthritis (OA) tissue pathology in the mechanically stressed compartment using magnetic resonance imaging (MRI)., Methods: Individuals with knee OA underwent full-limb and knee radiographs and knee MRI. Linear regression was used to determine if the 2 angles differed systematically and to identify the cutoff. Alignment means for MRI grades were compared using Dunnett's t-test., Results: In the 146 participants (109 women, mean age 70 years, body mass index 30.6 kg/m(2)), femur-tibia and hip-knee-ankle angles correlated (r = 0.86; 95% confidence interval [95% CI] 0.81, 0.90). On average, the femur-tibia angle was 3.4 degrees more valgus (3.0 degrees in women and 4.7 degrees in men); after correction, its sensitivity and specificity (to predict the hip-knee-ankle angle) were 0.84 and 0.84 for identifying varus and 0.98 and 0.73 for valgus, respectively. The area under the ROC curve (95% CI) was 0.91 (0.86, 0.96) for varus and 0.94 (0.89, 0.99) for valgus. Varus severity worsened comparably with each alignment measure as medial lesion score on MRI worsened. Laterally, as lesion score worsened, comparably worse valgus was seen with either assessment approach., Conclusion: In knee OA, the knee radiograph femur-tibia and full-limb radiograph hip-knee-ankle angles were correlated. The femur-tibia angle, corrected for mean offset, was sensitive, specific, and had excellent discriminative ability for identifying varus and valgus alignment evidenced by area under the ROC curve. The relationship between alignment and specific OA MRI features was comparable with the 2 approaches. Use of the femur-tibia angle, corrected for offset, should be considered in research and clinical settings.

OBJECTIVES:Disability prevention strategies are more achievable before osteoarthritis disease drives impairment. It is critical to identify high-risk groups, for strategy implementation and trial eligibility. An established measure, gait speed is associated with disability and mortality. We sought to develop and validate risk stratification trees for incident slow gait in persons at high risk for knee osteoarthritis, feasible in community and clinical settings. METHODS:Osteoarthritis Initiative (derivation cohort) and Multicenter Osteoarthritis Study (validation cohort) participants at high risk for knee osteoarthritis were included. Outcome was incident slow gait over up to 10-year follow-up. Derivation cohort classification and regression tree analysis identified predictors from easily assessed variables and developed risk stratification models, then applied to the validation cohort. Logistic regression compared risk group predictive values; area under the receiver operating characteristic curves (AUCs) summarised discrimination ability. RESULTS:1870 (derivation) and 1279 (validation) persons were included. The most parsimonious tree identified three risk groups, from stratification based on age and WOMAC Function. A 7-risk-group tree also included education, strenuous sport/recreational activity, obesity and depressive symptoms; outcome occurred in 11%, varying 0%-29 % (derivation) and 2%-23 % (validation) depending on risk group. AUCs were comparable in the two cohorts (7-risk-group tree, 0.75, 95% CI 0.72 to 0.78 (derivation); 0.72, 95% CI 0.68 to 0.76 (validation)). CONCLUSIONS:In persons at high risk for knee osteoarthritis, easily acquired data can be used to identify those at high risk of incident functional impairment. Outcome risk varied greatly depending on tree-based risk group membership. These trees can inform individual awareness of risk for impaired function and define eligibility for prevention trials.

INTRODUCTION:Physical activity guidelines recommend minimum thresholds. This study sought to identify evidence-based thresholds to maintain disability-free status over 4years among adults with lower extremity joint symptoms. METHODS:Prospective multisite Osteoarthritis Initiative accelerometer monitoring cohort data from September 2008 through December 2014 were analyzed. Adults (n=1,564) aged ≥49years at elevated disability risk because of lower extremity joint symptoms were analyzed for biennial assessments of disability-free status from gait speed ≥1meter/second (mobility disability-free) and self-report of no limitations in activities of daily living (activities of daily living disability-free). Classification tree analyses conducted in 2017-2018 identified optimal thresholds across candidate activity intensities (sedentary, light, moderate-vigorous, total light and moderate-vigorous activity, and moderate-vigorous accrued in bouts lasting ≥10 minutes). RESULTS:Minimal thresholds of 56 and 55 moderate-vigorous minutes/week best predicted disability-free status over 4years from mobility and activities of daily living disabilities, respectively, across the candidate measures. Thresholds were consistent across sex, BMI, age, and knee osteoarthritis presence. Mobility disability onset was one eighth as frequent (3% vs 24%, RR=0.14, 95% CI=0.09, 0.20) and activities of daily living disability onset was almost half (12% vs 23%, RR=0.55, 95% CI=0.44, 0.70) among people above versus below the minimum threshold. CONCLUSIONS:Attaining an evidence-based threshold of approximately 1-hour moderate-vigorous activity/week significantly increased the likelihood of maintaining disability-free status over 4years. This minimum threshold tied to maintaining independent living abilities has value as an intermediate goal to motivate adults to take action towards the many health benefits of a physically active lifestyle.

ObjectiveValidation of a symptom measure for early knee OA may help identify new treatments and modifiable risk factors. Symptom measures that consider pain in the context of activity level may provide better discrimination than pain alone. Therefore, we aimed to compare sensitivity to change for radiographic progression between Ambulation Adjusted Score for Knee pain (AASK), which accounts for self-reported ambulation, and Western Ontario McMaster Osteoarthritis (WOMAC) knee pain score.DesignParticipants were assessed annually up to 48 months using WOMAC, Physical Activity Scale for the Elderly (PASE) ambulation, and knee radiographs. AASK was defined as ((WOMAC pain) + 1)/((average daily hours of walking) + 1). Radiographs were scored for Kellgren-Lawrence (KL) grade. Linear regression, stratified by OA status, evaluated relationships between changes in AASK and WOMAC pain and KL grade over time.ResultsFor 4191 people (8030 knees), the mean age was 61.2 (+ 9.2) years old and BMI was 28.6 (+ 4.8) kg/m2; 58% female. Over 40% of knees had WOMAC pain scores of 0; by design, no knees had AASK scores of 0. Annual changes in AASK were more sensitive to changes in KL than changes in WOMAC in those without baseline OA (0.20 and 0.16 change per unit KL change, p = 0.005 and 0.070 respectively), but performed similarly in knees with OA.ConclusionAASK is simple to assess using existing validated questionnaires. AASK performs well in individuals with and without OA and should be considered in clinical trials and observational studies of early knee OA.

INTRODUCTION:While OA literature indicates greater pain is related to less time being physically active, it is not known if time curtailment occurs primarily for moderate intensity activities or for light activities or in both. We examine the cross-sectional association of knee pain with physical activity using data from 1874 Osteoarthritis Initiative participants. METHODS:Knee pain characteristics of constant and intermittent pain were each scored by the Intermittent and Constant Osteoarthritis Pain instrument and categorized into four pain levels (no pain, intermittent pain below and above median level, and constant pain). The relationships between knee pain levels and objectively measured physical activity (average weekly moderate or light intensity minutes) were assessed by quantile regression adjusted for socio-demographics and health factors. RESULTS:Knee pain levels had a strong negative relationship with moderate intensity physical activities (p-value for trend =0.029). Compared to the no pain group, persons with more severe knee pain, particularly those reporting higher intermittent or constant pain spent less time in moderate activity. In contrast, there was no notable trend related to pain with time spent in light intensity activity. These patterns remained when restricted to persons with clinical evidence (symptoms and/or radiographic) of knee OA and among persons not using medications for knee symptoms. CONCLUSION:Greater knee pain levels were strongly related to less moderate intensity activity time, but not time spent in light intensity physical activity. This relationship suggests that light activity may be a more acceptable way to increase physical activity than moderate activity for people with symptomatic knee pain.

ObjectivePain is not always correlated with severity of radiographic osteoarthritis (OA), possibly because people modify activities to manage symptoms. Measures of symptoms that consider pain in the context of activity level may therefore provide greater discrimination than a measure of pain alone. We undertook this study to compare discrimination provided by a measure of pain alone with that provided by combined measures of pain in the context of physical activity across radiographic OA severity levels.MethodsThis was a cross-sectional study nested within the Osteoarthritis Initiative (OAI). The population was drawn from 2,127 persons enrolled in an OAI accelerometer monitoring substudy, including those with and those without knee OA. Two composite pain and activity knee symptom (PAKS) scores were calculated as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score (plus 1) divided by a physical activity measure (step count for the first PAKS score [PAKS1 score] and activity count for the second PAKS score [PAKS2 score]). Symptom score discrimination across Kellgren/Lawrence (K/L) grades was evaluated using histograms and quantile regression.ResultsA total of 1,806 participants (55.5% of whom were women) were included (mean ± SD age 65.1 ± 9.1 years, mean ± SD body mass index 28.4 ± 4.8 kg/m(2) ). The WOMAC pain score, but not the PAKS scores, exhibited a floor effect. The adjusted median WOMAC pain scores by K/L grades 0-4 were 0, 0, 0, 1, and 3, respectively. The adjusted median PAKS1 scores were 24.9, 26.0, 32.4, 46.1, and 97.9, respectively, and the adjusted median PAKS2 scores were 7.2, 7.2, 9.2, 12.9, and 23.8, respectively. The PAKS scores had more statistically significant comparisons between K/L grades than did the WOMAC pain score.ConclusionSymptom assessments incorporating pain and physical activity did not exhibit a floor effect and were better able to discriminate radiographic severity than an assessment of pain alone, particularly in milder disease. Pain in the context of physical activity level should be used to assess knee OA symptoms.

ObjectiveTo investigate the public health impact of obesity and other modifiable risk factors related to physical inactivity in adults with knee osteoarthritis (OA).MethodsThe frequency of inactivity as defined by the US Department of Health and Human Services was assessed from objective accelerometer monitoring of 1,089 participants (ages 49-84 years) with radiographic knee OA during the Osteoarthritis Initiative 48-month visit (2008-2010). The relationship between modifiable factors (weight status, dietary fat, fiber, smoking, depressive symptoms, knee function, knee pain, and knee confidence) with inactivity was assessed using odds ratios (ORs) and attributable fractions (AFs), controlling for descriptive factors (age, sex, race, education, lives alone, employment, frequent knee symptoms, and comorbidity).ResultsAlmost half (48.9%) of participants with knee OA were inactive. Being overweight (OR 1.8, 95% confidence interval [95% CI] 1.2-2.5) or obese (OR 3.9, 95% CI 2.6-5.7), having inadequate dietary fiber intake (OR 1.6, 95% CI 1.2-2.2), severe knee dysfunction (OR 1.9, 95% CI 1.3-2.8), and severe pain (OR 1.7, 95% CI 1.1-2.5) were significantly related to inactivity, controlling for descriptive factors. Modifiable factors with significant average AFs were being overweight or obese (AF 23.8%, 95% CI 10.5-38.6%) and inadequate dietary fiber (AF 12.1%, 95% CI 0.1-24.5%), controlling for all factors.ConclusionBeing obese or overweight, the quality of the diet, severe pain, and severe dysfunction are significantly associated with physical inactivity in adults with knee OA. All components should be considered in designing physical activity interventions that target arthritis populations with low activity levels.

Objective: To identify modifiable physical and behavioural factors associated with widespread pain (WSP) in older adults with radiographic evidence of knee osteoarthritis (OA). Methods: Cross‐sectional initial visit data of participants with radiographic knee OA (Kellgren‐Lawrence grade of ≥2) from the Osteoarthritis Initiative Study were analysed. WSP was defined as pain on both sides of the body, above and below the waist, and in the axial skeleton. Time (hrs/d) spent participating in sitting and moderate‐strenuous physical activities were calculated from the Physical Activity Scale for the Elderly questionnaire. Physical function was quantified using gait speed and the chair stand test. Restless sleep was assessed using an item on the CES‐D Scale. Logistic regression models were constructed to examine the strength of the associations between primary exposures and WSP in unadjusted and adjusted analyses. Results: Among the 2637 participants (mean age 62.6 years, 58.6% female), 16.8% met the criteria for WSP. All primary measures of interest were related to WSP in unadjusted analyses. In adjusted multivariable analysis, slow gait speed (adjusted odds ratio [aOR] 1.43; 95% CI 1.01, 2.02), lower chair stand rate (aOR 0.98; 95% CI 0.97–0.99), and restless sleep (aOR 1.61; 95% CI 1.25–2.08) maintained significant associations with WSP. Conclusion: Poor sleep behaviours and low physical function capacity are associated with WSP in adults with radiographic knee OA. These findings highlight the importance of assessing sleep, physical function, and pain distribution in this population. Interventions to improve physical function and sleep behaviours should be investigated as potential strategies to mitigate WSP. [ABSTRACT FROM AUTHOR]

Objective: Little is known regarding what difference in functional performance measures is significant in individuals with chronic medical disease. Our objective was to examine the important differences in gait speed in adults with radiographic knee osteoarthritis. Methods: Functional performance was measured by gait speed using 20‐meter and 400‐meter walk tests performed at a self‐selected usual pace among adults with radiographic knee osteoarthritis participating in the Osteoarthritis Initiative at baseline and 2 years later. Both distribution‐based methods and anchor‐based methods were used to calculate the important differences in gait speed. Anchor‐based methods used the chair stand rate and self‐reported function to estimate gait speed differences related to physical function. Results: We included 2,527 participants with radiographic knee osteoarthritis. Distribution‐based important difference estimates for the 20‐meter walk ranged from 4.1 to 6.4 meters/minute and 400‐meter walk estimates ranged from 2.9 to 6.5 meters/minute. Prevalent (cross‐sectional) anchor‐based estimates for the 20‐meter walk ranged from 5.4 to 6.9 meters/minute and for the 400‐meter walk ranged from 3.0 to 6.9 meters/minute. Longitudinal anchor‐based estimates were deemed unreliable. Combining distribution‐based with prevalent anchor‐based methods showed that an important gait speed difference for the 20‐meter walk is between 4.1 and 6.9 meters/minute and for the 400‐meter walk is between 2.9 and 6.9 meters/minute. Conclusion: Our results found that the important difference in gait speed for the 20‐meter walk and the 400‐meter walk is consistent with important difference estimates for older adult populations. These findings can provide benchmarks for assessing and understanding functional performance outcomes when comparing exposure groups and can be used in designing future studies targeting adults with radiographic knee osteoarthritis. [ABSTRACT FROM AUTHOR]

OBJECTIVES Physical activity is associated with improved pain, functional status, and less disability in persons with knee osteoarthritis (KOA). Because polypharmacy is related to several adverse health outcomes in older persons, we hypothesized that it might also be associated with decreased physical activity in those with KOA. This study evaluates the relationship between the number of prescription medications and weekly moderate to vigorous physical activity (MVPA). DESIGN We used hierarchical median quantile regression analysis to examine the cross‐sectional association between the number of prescription medications taken in the past 30 days and the median objectively measured MVPA minutes controlling for demographic and clinical variables. SETTING Four Osteoarthritis Initiative (OAI) recruitment centers in Providence, Rhode Island; Columbus, Ohio; Baltimore, Maryland; and Pittsburgh, Pennsylvania. PARTICIPANTS Accelerometer monitoring occurred in 2,127 OAI participants. Of these, 1,889 participants had 4 or more days of valid physical activity monitoring data and complete medication/covariate data. Data were collected at the 48‐month OAI follow‐up visit (2008‐2010). MEASUREMENTS The outcome was weekly minutes of MVPA measured with an accelerometer. Number/type of prescribed medications and covariate data (age, sex, race/ethnicity, body mass index, presence of comorbidities, pain, depressive symptoms, and radiographic KOA severity) were taken from the public OAI database. Polypharmacy was defined as taking five or more prescribed medications. RESULTS: The prevalence of polypharmacy in the study population was 28.2%. Each additional prescription medication was related to a decrease of 3.6 minutes (95% confidence interval [CI] = −4.8 to −2.1) in median weekly MVPA minutes. Participants meeting the polypharmacy criterion exhibited a decrease of 12.6 minutes (95% CI = −21.2 to −4.7) in median weekly MVPA minutes compared with those not meeting the criterion. CONCLUSION: An increased number of prescription medications and polypharmacy are associated cross‐sectionally with decreased MVPA in adults with KOA. Further study is necessary to establish the causal nature of this association. [ABSTRACT FROM AUTHOR]

Objective: Examine whether pre‐intervention physical activity (PA) level is associated with achieving a positive treatment response of pain and/or function improvement after a 12‐week exercise intervention in participants with knee osteoarthritis (OA). Methods: We performed a secondary analysis of a randomized, single‐blind comparative effectiveness trial showing similar treatment effects between Tai Chi mind‐body exercise and standard physical therapy intervention for knee OA. Baseline PA was assessed by a Community Healthy Activities Model Program for Seniors (CHAMPS) questionnaire and, in a subsample, by tri‐axial accelerometers. The Outcome Measures in Rheumatoid Arthritis Clinical Trials–Osteoarthritis Research Society International (OMERACT‐OARSI) dichotomous responder criteria was used for clinically meaningful improvement at follow‐up. Associations between baseline self‐reported PA by the CHAMPS questionnaire and outcomes of responders vs. nonresponders (reference group) were assessed using logistic regressions, adjusting for demographic covariates. We compared objectively measured PA by accelerometry between responders vs. nonresponders using Wilcoxon tests. Results: Our sample consisted of 166 participants with knee OA who completed both baseline and 12‐week postintervention evaluations: mean age 60.7 year (SD 10.5), body mass index 32.4 kg/m2 (6.9), 119 (72%) women, and 138 (83%) OMERACT‐OARSI responders. Neither time spent in total PA [odds ratio (OR) 1.00; 95% confidence interval (CI) 0.96, 1.03] nor time in moderate‐to‐vigorous PA (OR 1.01; 95% CI 0.93, 1.09) at pre‐intervention were associated with being a responder. Similar findings were observed in 42 accelerometry sub‐cohort participants. Conclusion: Pre‐intervention PA levels (subjective report or objective measurement) were not associated with individuals achieving favorable treatment outcomes after a 12‐week exercise intervention, which suggests that regardless of pre‐intervention PA level, individuals will likely benefit from structured exercise interventions. [ABSTRACT FROM AUTHOR]

Background Arthritis is a leading cause of chronic pain and functional limitations. Exercise is beneficial for improving strength and function and decreasing pain. We evaluated the effect of a motivational interviewing-based lifestyle physical activity intervention on self-reported physical function in adults with knee osteoarthritis (KOA) or rheumatoid arthritis (RA). Methods Participants were randomized to intervention or control. Control participants received a brief physician recommendation to increase physical activity to meet national guidelines. Intervention participants received the same brief baseline physician recommendation in addition to motivational interviewing sessions at baseline, 3, 6, and 12 months. These sessions focused on facilitating individualized lifestyle physical activity goal setting. The primary outcome was change in self-reported physical function. Secondary outcomes were self-reported pain and accelerometer-measured physical activity. Self-reported KOA outcomes were evaluated by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for KOA (WOMAC scores range from 0 to 68 for function and 0 to 20 for pain) and the Health Assessment Questionnaire (HAQ) for RA. Outcomes were measured at baseline, 3, 6, 12, and 24 months. Multiple regression accounting for repeated measures was used to evaluate the overall intervention effect on outcomes controlling for baseline values. Results Participants included 155 adults with KOA (76 intervention and 79 control) and 185 adults with RA (93 intervention and 92 control). Among KOA participants, WOMAC physical function improvement was greater in the intervention group compared to the control group [difference = 2.21 (95% CI: 0.01, 4.41)]. WOMAC pain improvement was greater in the intervention group compared to the control group [difference = 0.70 (95% CI: −0.004, 1.41)]. There were no significant changes in physical activity. Among RA participants, no significant intervention effects were found. Conclusion Participants with KOA receiving the lifestyle intervention experienced modest improvement in self-reported function and a trend toward improved pain compared to controls. There was no intervention effect for RA participants. Further refinement of this intervention is needed for more robust improvement in function, pain, and physical activity. [ABSTRACT FROM AUTHOR]

Objective To evaluate whether low knee confidence at baseline is associated with poor baseline-to-3-year physical function outcome in the Osteoarthritis Initiative. Methods Knee confidence was assessed using an item from the Knee Injury and Osteoarthritis Outcome Score instrument. Physical function was assessed using self-report measures (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] function score and Short Form 12 physical component scale) and performance-based measures (20-meter walk and chair stand test). Poor function outcome was defined as moving into a worse function group or remaining in the 2 worst function groups between baseline and 3 years. Logistic regression was used to evaluate the relationship between baseline knee confidence level and poor baseline-to-3-year function outcome, adjusting for potential confounders. Results The sample included 3,975 men and women with or at high risk of developing osteoarthritis of the knee, of whom 37-53% had poor baseline-to-3-year function outcome. For both self-report measures, increasingly worse knee confidence was associated with a greater risk of poor function outcome, and trend tests supported a graded response (e.g., the adjusted odds ratios [95% confidence intervals] for the WOMAC function score for worsening confidence categories were 1.26 [1.07-1.49], 1.43 [1.16-1.77], and 2.05 [1.49-2.82], P for trend <0.0001). Similar associations between confidence and performance-based function outcome were observed, but statistical significance did not persist in adjusted analyses. Factors independently associated with poor function outcome for all 4 outcome measures were depressive symptoms, comorbidity, body mass index, and joint space narrowing. Conclusion These findings indicate that worse knee confidence at baseline is independently associated with greater risk of poor function outcome by self-report measures, with evidence of a graded response; the relationship with performance measures is not significant in fully adjusted models. [ABSTRACT FROM AUTHOR]

Abstract: Dunlop DD, Semanik P, Song J, Sharma L, Nevitt M, Mysiw J, Chang RW, for the Osteoarthritis Initiative Investigators. Moving to maintain function in knee osteoarthritis: evidence from the Osteoarthritis Initiative. Objectives: To investigate the association between baseline physical activity and 1-year functional performance in adults with knee osteoarthritis (OA). Design: Prospective cohort study of knee OA development and progression with 1-year follow-up. Setting: Community. Participants: Osteoarthritis Initiative public data on adults with knee OA (n=2274; age, 45–79y) who participated in functional performance assessments (timed 20-m walk and chair stand test) at baseline and 1-year follow-up. Interventions: Not applicable. Main Outcome Measure: A good 1-year performance outcome (separately defined for walk time and chair stand measures) was improvement from baseline quintile or maintenance in the best quintile. Results: Almost 2 in 5 persons with radiographic knee OA improved or maintained high performance at 1 year. Physical activity measured by the Physical Activity Scale for the Elderly (PASE) was significantly associated with good walk rate and chair stand outcomes (odds ratio per 40 units PASE [95% confidence interval]=1.13 [1.13, 1.17] and 1.10 [1.05, 1.15], respectively), as were participation in sports/recreational activities (1.45 [1.23, 1.71] and 1.29 [1.09, 1.51], respectively) and lifestyle activities (1.11 [1.06, 1.16] and 1.09 [1.04, 1.14], respectively). An independent protective relationship for these physical activity measures approached significance after adjusting for sociodemographic and health factors. Older adults reported the least baseline physical activity and least frequent good 1-year outcomes. Conclusions: These findings support public health recommendations to be physically active in order to preserve function for persons with knee OA. Physical activity messages should specifically target older adults whose low activity levels may jeopardize their ability to maintain functional performance. [Copyright &y& Elsevier]

The article presents a study that examines the presence of varus and valgus thrust on patients with or at higher risk of medial knee osteoarthritis (OA) from different racial groups. It states that the study performed the Osteoarthritis Initiative (OAI) observational cohort study among men and women, who were diagnosed with OA or at higher risk of OA. It reveals that African Americans have lower odds of varus thrust and higher odds of valgus thrust than Caucasians.

Presents a study to test the hypotheses that varus alignment increases risk of medial knee osteoarthritis (OA) progression during the subsequent 18 months, valgus alignment increases risk of subsequent lateral knee OA progression, greater severity of malalignment is associated with greater subsequent loss of joint space, and greater burden of malalignment is associated with greater subsequent decline in physical function. Design and setting; Participants; Main outcome measures; Results; Conclusions.

A response by G. H Lo and colleagues to a letter to the editor about their article "Symptom assessment in knee osteoarthritis needs to account for physical activity level" in the 2015 issue is presented.

Introduction: Knee pain may preclude participation in higher intensity physical activity in people with knee osteoarthritis and benefits of light activity are unclear. The effect of replacing sedentary time with light intensity activity on incident functional limitation 2 years later was investigated.Methods: Included were people with or at high risk of knee osteoarthritis without baseline functional limitation using data from the Osteoarthritis Initiative collected between August 2008 and July 2010. Data were analyzed between May 2016 and August 2016 for time in sedentary, light, and moderate to vigorous physical activity from accelerometer monitoring. Incident functional limitation was defined as (1) slow gait speed <1.0 meters/second during a 20-meter walk, (2) Western Ontario and McMasters University Osteoarthritis Index physical function ≥28, or (3) Short Form 12 Physical Component scale <40.Results: Inclusion criteria were met by 1,873 people (mean age=65.0 [SD=9.0] years, mean BMI=28.4 [SD=4.7] kg/m2). Replacing 60 minutes/day of sedentary time with 60 minutes/day of light activity was associated with a 17% reduced risk for incident slow gait speed 2 years later (Hazard Ratio=0.83, 95% CI=0.70, 0.99) after adjustment. Approximately 5 minutes/day of moderate to vigorous physical activity would be necessary to receive the equivalent benefit of 60 minutes/day of light activity. Effects in secondary patient-reported outcomes did not reach statistical significance.Conclusions: Replacing sedentary time with light activity may reduce the risk of performance-based functional limitation. As expected, moderate to vigorous physical activity rather than light provided stronger risk reduction. When moderate to vigorous physical activity is not an option, pursuing light activity may be a beneficial alternative to being sedentary. [ABSTRACT FROM AUTHOR]