Risk Of Symptomatic Knee Osteoarthritis Research Articles

Association of Diabetes Mellitus Status and Hyperglycemia With Symptomatic Knee Osteoarthritis.

Emerging evidence indicates that hyperglycemia has an adverse impact on the knee joint which, in turn, may increase the risk of knee osteoarthritis (OA), but evidence from the real-life settings of large-scale cohort studies remains unclear. We sought to evaluate the association of glycemic control and the risk of symptomatic knee OA in a community-based cohort of older adults. We conducted a prospective analysis of 10,730 participants without knee OA. Comprehensive blood biomarker data were obtained. Diabetes mellitus (DM) was defined mainly using a glycosylated hemoglobin (HbA1c ) level of ≥6.5%; poor glycemic control in individuals with DM was defined as an HbA1c level of ≥7%. We fit Cox regression models, stratified according to DM status. We evaluated the hazards associated with HbA1c and fasting blood glucose levels using a spline model. During a median follow-up of 5 years, knee OA developed in 1,089 participants (108 with DM and 971 without). Knee OA was related to DM (hazard ratio [HR] 1.29 [95% confidence interval (95% CI) 1.02-1.78]), bad glycemic regulation in DM patients (HR 1.41 [95% CI 1.05-2.09]), and long-term DM (≥5 versus <5 years; HR 1.49 [95% CI 1.02-2.17]). High levels of HbA1c (>7.7% and 61 mmoles/mole) and fasting blood glucose (>186 mg/dl) were significantly associated with higher risk of incident knee OA. DM, bad glycemic management, and long-term DM are potential risk factors of symptomatic knee OA independent of age and body mass index. Targeting blood glucose, in addition to bodyweight, may be an important avenue for prevention of knee OA.

Development of a model for predicting the 4-year risk of symptomatic knee osteoarthritis in China: a longitudinal cohort study

ObjectivesWe aimed to develop a model for predicting the 4-year risk of knee osteoarthritis (KOA) based on survey data obtained via a random, nationwide sample of Chinese individuals.MethodsData was analyzed from 8193 middle-aged and older adults included in the China Health and Retirement Longitudinal Study (CHARLS). The incident of symptomatic KOA was defined as participants who were free of symptomatic KOA at baseline (CHARLS2011) and diagnosed with symptomatic KOA at the 4-year follow-up (CHARLS2015). The effects of potential predictors on the incident of KOA were estimated using logistic regression models and the final model was internally validated using the bootstrapping technique. Model performance was assessed based on discrimination—area under the receiver operating characteristic curve (AUC)—and calibration.ResultsA total of 815 incidents of KOA were identified at the 4-year follow-up, resulting in a cumulative incidence of approximately 9.95%. The final multivariable model included age, sex, waist circumference, residential area, difficulty with activities of daily living (ADLs)/instrumental activities of daily living (IADLs), history of hip fracture, depressive symptoms, number of chronic comorbidities, self-rated health status, and level of moderate physical activity (MPA). The risk model showed good discrimination with AUC = 0.719 (95% confidence interval [CI] 0.700–0.737) and optimism-corrected AUC = 0.712 after bootstrap validation. A satisfactory agreement was observed between the observed and predicted probability of incident symptomatic KOA. And a simple clinical score model was developed for quantifying the risk of KOA.ConclusionOur prediction model may aid the early identification of individuals at the greatest risk of developing KOA within 4 years.

Depression Subtypes in Individuals With or at Risk for Symptomatic Knee Osteoarthritis.

The present study was undertaken to identify depression subtypes in individuals with or at risk for symptomatic knee osteoarthritis (OA) and to evaluate differences in pain and disability trajectories between groups. Participants (n = 4,486) were enrolled in the Osteoarthritis Initiative. Latent class analysis was applied to the 20-item Center for Epidemiologic Studies Depression Scale measured at baseline to identify groups with similar patterns of depressive symptoms, and subtypes were assigned using posterior probability estimates. The relationships between depression subtypes and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and disability subscales were modeled over 4 years and stratified by baseline knee OA status (symptomatic [n = 1,626] or at risk [n = 2,860]). Four subtypes were identified: asymptomatic (80.6%), catatonic (5.3%), anhedonic (10.6%), and melancholic (3.5%). Catatonic and anhedonic subtypes were differentiated by symptoms corresponding to psychomotor agitation and the inability to experience pleasure, respectively. The melancholic subtype expressed symptoms related to reduced energy and movement, anhedonia, and other somatic symptoms. Detectable mean differences in pain and disability compared to the asymptomatic group were observed for the anhedonic (1.5-2.3 WOMAC units) and melancholic (4.8-6.6 WOMAC units) subtypes, and associations were generally larger in individuals with symptomatic knee OA relative to those at risk. Among individuals with or at risk for symptomatic knee OA, there is evidence of depression subtypes characterized by distinct clusters of depressive symptoms that have differential effects on reports of pain and disability over time. Our findings thus imply that depression interventions could be optimized by targeting the specific symptomology that these subtypes exhibit.

Body Mass Index Mediates the Association between Dietary Fiber and Symptomatic Knee Osteoarthritis in the Osteoarthritis Initiative and the Framingham Osteoarthritis Study

Dietary fiber reduces body weight and inflammation in clinical trials. It is unclear whether body mass index (BMI) and inflammation might explain the observed association between higher fiber intake and the lower risk of symptomatic knee osteoarthritis (SXKOA). We quantified the extent to which BMI and inflammation influenced the relation between dietary fiber and SXKOA. We used longitudinal data from the Osteoarthritis Initiative (OAI) and the Framingham Offspring Osteoarthritis Study. At baseline of each study, men and women (mean age: 61 y) with or at risk of knee osteoarthritis were followed for 48 mo in the OAI. Adults (mean age: 53 y) were followed for 9.5 y in the Framingham study. Dietary fiber intake was estimated using a validated food-frequency questionnaire. Measured weight and height were used to calculate BMI. Serum high-sensitivity C-reactive protein (CRP) was measured in the Framingham study only. Incident SXKOA was defined as new onset of a combination of knee pain and radiographic osteoarthritis. We applied marginal structural models to quantify the mediation through BMI in the OAI and the sequential mediation through BMI and CRP in the Framingham study. Incident SXKOA occurred in 861 knees among 2876 persons in the OAI and in 143 knees among 971 persons in the Framingham study. In persons whose fiber intake was ≥21 g/d compared with those with intakes <21 g/d, the OR (95% CI) was 0.70 (0.53, 0.91) for the overall association with SXKOA and was 0.93 (0.92, 0.95) for the mediation via BMI (per kg/m2) in the OAI. In the Framingham study, the overall association was 0.57 (0.30, 1.09), the mediation through BMI (via BMI and the influence of BMI on CRP) was 0.94 (0.85, 1.02), and the mediation through CRP (per milligram per liter) was 0.99 (0.84, 1.19). Our findings suggest that the inverse association of fiber intake and the risk of incident symptomatic knee osteoarthritis is partially mediated by BMI.

Optimism and Psychological Resilience are Beneficially Associated With Measures of Clinical and Experimental Pain in Adults With or at Risk for Knee Osteoarthritis.

This cross-sectional study examined the associations among optimism, psychological resilience, endogenous pain inhibition, and clinical knee pain severity. Two hypotheses were tested. First, we hypothesized that experimentally tested endogenous pain inhibition would mediate the relationship between optimism and clinical knee pain severity. Second, it was also hypothesized that optimism would moderate the relationships of psychological resilience with endogenous pain inhibition and clinical knee pain severity, particularly for individuals with high optimism. A total of 150 individuals with or at risk for symptomatic knee osteoarthritis completed the Life Orientation Test-Revised, the Brief Resilience Scale, and the revised Short-Form McGill Pain Questionnaire-2 to assess optimism, psychological resilience, and clinical knee pain severity, respectively. Endogenous pain inhibition was examined experimentally using a conditioned pain modulation (CPM) protocol with algometry (test stimulus) and a cold pressor task (conditioning stimulus). As hypothesized, results showed that increased CPM significantly mediated the association between higher optimism and lower clinical knee pain severity. Further, optimism moderated the association between psychological resilience and CPM. However, contrary to our hypothesis, greater psychological resilience was associated with enhanced CPM in individuals with low optimism only. This study suggests that an optimistic outlook may beneficially impact clinical pain severity by altering endogenous pain modulatory capacity. Furthermore, individuals with low optimism (ie, pessimists) may be more adept at engaging resources that promote psychological resilience, which in turn, enhances endogenous pain modulatory capacity. Therefore, this study supports consideration of psychological resilience factors when evaluating experimental and clinical pain outcomes.

Lifetime Risk of Symptomatic Hand Osteoarthritis: The Johnston County Osteoarthritis Project.

Symptomatic hand osteoarthritis (OA) is a common condition that affects hand strength and function, and causes disability in activities of daily living. Prior studies have estimated that the lifetime risk of symptomatic knee OA is 45% and that of hip OA is 25%. The objective of the present study was to estimate the overall lifetime risk of symptomatic hand OA, and the stratified lifetime risk according to potential risk factors. Data were obtained from 2,218 adult subjects (ages ≥45 years) in the Johnston County Osteoarthritis Project, a population-based prospective cohort study among residents of Johnston County, North Carolina. Data for the present study were collected from 2 of the follow-up cycles (1999-2004 and 2005-2010). Symptomatic hand OA was defined as the presence of both self-reported symptoms and radiographic OA in the same hand. Lifetime risk, defined as the proportion of the population who will develop symptomatic hand OA in at least 1 hand by age 85 years, was estimated from models using generalized estimating equations. Overall, the lifetime risk of symptomatic hand OA was 39.8% (95% confidence interval [95% CI] 34.4-45.3%). In this population, nearly 1 in 2 women (47.2%, 95% CI 40.6-53.9%) had an estimated lifetime risk of developing symptomatic hand OA by age 85 years, compared with 1 in 4 men (24.6%, 95% CI 19.5-30.5%). Race-specific symptomatic hand OA risk estimates were 41.4% (95% CI 35.5-47.6%) among whites and 29.2% (95% CI 20.5-39.7%) among African Americans. The lifetime risk of symptomatic hand OA among individuals with obesity (47.1%, 95% CI 37.8-56.7%) was 11 percentage points higher than that in individuals without obesity (36.1%, 95% CI 29.7-42.9%). These findings demonstrate the substantial burden of symptomatic hand OA overall and in sociodemographic and clinical subgroups. Increased use of public health and clinical interventions is needed to address its impact.

Is There an Association Between a History of Running and Symptomatic Knee Osteoarthritis? A Cross-Sectional Study From the Osteoarthritis Initiative.

Regular physical activity, including running, is recommended based on known cardiovascular and mortality benefits. However, controversy exists regarding whether running can be harmful to knees. The purpose of this study is to evaluate the relationship of running with knee pain, radiographic osteoarthritis (OA), and symptomatic OA. This was a retrospective cross-sectional study of Osteoarthritis Initiative participants (2004-2014) with knee radiograph readings, symptom assessments, and completed lifetime physical activity surveys. Using logistic regression, we evaluated the association of history of leisure running with the outcomes of frequent knee pain, radiographic OA, and symptomatic OA. Symptomatic OA required at least 1 knee with both radiographic OA and pain. Of 2,637 participants, 55.8% were female, the mean ± SD age was 64.3 ± 8.9 years, and the mean ± SD body mass index was 28.5 ± 4.9 kg/m2 ; 29.5% of these participants ran at some time in their lives. Unadjusted odds ratios of pain, radiographic OA, and symptomatic OA for those prior runners and current runners compared to those who never ran were 0.83 and 0.71 (P for trend = 0.002), 0.83 and 0.78 (P for trend = 0.01), and 0.81 and 0.64 (P for trend = 0.0006), respectively. Adjusted models were similar, except radiographic OA results were attenuated. There is no increased risk of symptomatic knee OA among self-selected runners compared with nonrunners in a cohort recruited from the community. In those without OA, running does not appear to be detrimental to the knees.

Projecting Lifetime Risk of Symptomatic Knee Osteoarthritis and Total Knee Replacement in Individuals Sustaining a Complete Anterior Cruciate Ligament Tear in Early Adulthood

To estimate the lifetime risk of knee osteoarthritis (OA) and total knee replacement (TKR) in persons sustaining anterior cruciate ligament (ACL) tear by age 25 years. We used the Osteoarthritis Policy Model to project the cumulative incidence of symptomatic knee OA requiring TKR in varying situations: no prevalent or incident injury; isolated ACL tear, surgically treated; isolated ACL tear, nonoperatively treated; or a prevalent history or surgically treated ACL and meniscal tear (MT). We estimated MT prevalence and incidence and increased risk of knee OA associated with ACL injury and MT from published literature. We conducted a range of sensitivity analyses to examine the impact of uncertainty in input parameters. Estimated lifetime risk of symptomatic knee OA was 34% for the cohort with ACL injury and MT, compared to 14% for the no-injury cohort. ACL injury without MT was associated with a lifetime risk of knee OA between 16% and 17%, depending on ACL treatment modality. Estimated lifetime risk of TKR ranged from 6% in the no-injury cohort to 22% for the ACL injury and MT cohort. Subjects in the ACL injury and MT cohort developed OA approximately 1.5 years earlier (55.7 versus 57.1) and underwent TKR approximately 2 years earlier (66 versus 68) than the cohort without knee injuries. Sustaining ACL injury early in adulthood leads to greater lifetime risk and earlier onset of knee OA and TKR; concomitant MTs compound this risk. These data provide insight into the impact of sustainable injury prevention interventions in young adults.

Development and feasibility of a personalized, interactive risk calculator for knee osteoarthritis.

BackgroundThe incidence of knee osteoarthritis (OA) is rising. While several risk factors have been associated with the development of knee OA, this information is not readily accessible to those at risk for osteoarthritis. Risk calculators have been developed for several prevalent chronic conditions but not for OA. Using published evidence on established risk factors, we developed an interactive, personalized knee OA risk calculator (OA Risk C) and conducted a pilot study to evaluate its acceptability and feasibility.MethodsWe used the Osteoarthritis Policy (OAPol) Model, a validated, state-transition simulation of the natural history and management of OA, to generate data for OA Risk C. Risk estimates for calculator users were based on a set of demographic and clinical factors (age, sex, race/ethnicity, obesity) and select risk factors (family history of knee OA, occupational exposure, and history of knee injury). OA Risk C presents personalized risk of knee OA in several ways to maximize understanding among a wide range of users. We conducted a study of 45 subjects in a primary care setting to establish the feasibility and acceptability of the OA risk calculator. Pilot study participants were asked several questions regarding ease of use, clarity of presentation, and clarity of the graphical representation of their risk. These questions used a five-level agreement scale ranging from strongly disagree to strongly agree.ResultsOA Risk C depicts information about users’ risk of symptomatic knee OA in 5 year intervals. Study participants estimated their lifetime risk at 38 %, while their actual lifetime risk, as estimated by OA Risk C, was 25 %. Eighty-four percent of pilot study participants reported that OA Risk C was easy to understand, and 89 % agreed that the graphs depicting their risk were clear and comprehensible.ConclusionsWe have developed a personalized, computer-based OA risk calculator that is easy to use. OA Risk C may be utilized to estimate individuals’ knee OA risk and to deliver educational and behavioral interventions focused on osteoarthritis risk reduction.

Efficacy of Blood Flow-Restricted Low-Load Resistance Training For Quadriceps Strengthening in Men at Risk of Symptomatic Knee Osteoarthritis

Background:Greater quadriceps strength has been associated with lower risk of symptomatic knee osteoarthritis (OA) in older adults. However, factors that confer elevated risk of knee OA (eg, sedentary lifestyle, obesity, and knee injury) also contribute to a reduced tolerance of resistance training programs at ≥60% 1-repetition maximum (1RM). Therefore, the current study assessed whether concurrent application of blood flow restriction (BFR) to low-load resistance training is an efficacious and tolerable means of improving quadriceps strength in men at risk of symptomatic knee OA.Methods:Men older than age 45, with a history of knee injury or elevated body mass index (BMI), were randomized to low-load resistance training (30% 1RM) either with or without concurrent BFR. Isotonic double-leg press strength and isokinetic knee extensor strength were assessed before and after 4 weeks of training 3 times/wk. Knee pain (Knee Osteoarthritis Outcome Score) was assessed for tolerance.Results:Of the 42 men (mean age 56.1 ± 7.7 years) who were randomized, 41 completed the program. There were no significant intergroup differences in age, BMI, knee pathology, or muscle strength at baseline. Although leg press 1RM improved in both control and BFR groups, there were no significant intergroup differences in primary or secondary measures of muscle strength. The BFR was not associated with worsening of knee pain, but there was a significant improvement in knee pain in the control group.Conclusions:In comparison with training without BFR, addition of BFR to 30% 1RM resistance training for 4 weeks did not confer significantly greater increases in leg press or quadriceps strength in older men with risk factors for symptomatic knee OA.

Vibration Platform Training in Women at Risk for Symptomatic Knee Osteoarthritis

To determine whether a platform exercise program with vibration is more effective than platform exercise alone for improving lower limb muscle strength and power in women ages 45 to 60 with risk factors for knee osteoarthritis (OA). Randomized, controlled study. Academic center. A total of 48 women ages 45-60 years with risk factors for knee OA (a history of knee injury or surgery or body mass index ≥25 kg/m(2)). Subjects were randomly assigned to a twice-weekly lower limb exercise program (quarter squat, posterolateral leg lifts, calf raises, step-ups, and lunges) on either a vertically vibrating platform (35 Hz, 2 mm) or a nonvibrating platform. Change in isokinetic quadriceps strength, leg press power, and stair climb power by 12 weeks. A total of 39 of 48 enrolled participants completed the study (26 vibration and 13 control exercise). Nine participants discontinued the study after randomization mainly because of a lack of time. No intergroup differences in age, body mass index, or activity level existed. Isokinetic knee extensor strength did not significantly improve in either group. Leg press power improved by 92.0 ± 69.7 W in the vibration group (P < .0001) and 58.2 ± 96.2 W in the control group (P = .0499) but did not differ between groups (P = .2262). Stair climb power improved by 53.4 ± 64.7 W in the vibration group (P = .0004) and 55.7 ± 83.3 W in the control group (P = .0329) but did not differ between groups (P = .9272). Whole body vibration platforms have been marketed for increasing strength and power. In this group of asymptomatic middle-aged women with risk factors for knee OA, the addition of vibration to a 12-week exercise program did not result in significantly greater improvement in lower limb strength or power than did participation in the exercise program without vibration.

The longitudinal relationship between thigh muscle mass and the development of knee osteoarthritis

Greater quadriceps strength has been found to reduce risk for symptomatic knee osteoarthritis (SxKOA) and knee joint space narrowing (JSN). However, this finding could relate to muscle mass or activation pattern. The purpose of this study was to assess whether greater thigh muscle mass protects against (1) incident radiographic (RKOA), (2) incident SxKOA or (3) worsening of knee JSN by 30-month follow-up. Multicenter Osteoarthritis (MOST) study participants, who underwent dual-energy X-ray absorptiometry (DXA) at the Iowa site were included. Thigh muscle mass was calculated from DXA image sub-regions. Sex-stratified, knee-based analyses controlled for incomplete independence between limbs within subjects. The effect of thigh lean mass and specific strength as predictors of ipsilateral RKOA, SxKOA and worsening of JSN were assessed, while controlling for age, body mass index (BMI), and history of knee surgery. A total of 519 men (948 knees) and 784 women (1453 knees) were included. Mean age and BMI were 62 years and 30kg/m(2). Thigh muscle mass was not associated with risk for RKOA, SxKOA or knee JSN. However, in comparison with the lowest tertile, those in the highest and middle tertiles of knee extensor specific strength had a lower risk for SxKOA and JSN [odds ratio (OR) 0.29-0.68]. Thigh muscle mass does not appear to confer protection against incident or worsening knee OA. These findings suggest that future studies of risk for knee OA should focus on the roles of knee extensor neuromuscular activation and muscle physiology, rather than the muscle mass.

A role for PACE4 in osteoarthritis pain: evidence from human genetic association and null mutant phenotype

ObjectivesThe aim of this study was to assess if genetic variation in the PACE4 (paired amino acid converting enzyme 4) gene Pcsk6 influences the risk for symptomatic knee osteoarthritis (OA).MethodsTen...

The Ile585Val TRPV1 variant is involved in risk of painful knee osteoarthritis

ObjectiveTo assess if a coding variant in the gene encoding transient receptor potential cation channel, subfamily V, member 1 (TRPV1) is associated with genetic risk of painful knee osteoarthritis (OA).MethodsThe...

Association Between Comorbid Depression and Osteoarthritis Symptom Severity in Patients with Knee Osteoarthritis

We sought to investigate the reported association between depression and severity of knee osteoarthritis symptoms stratified by radiographic severity of osteoarthritis and to quantify the contribution made by depression to symptom severity. Six hundred and sixty elderly Koreans (sixty-five years or older) were evaluated for radiographic severity of knee osteoarthritis on the basis of the Kellgren-Lawrence grading system and also for symptom severity on the basis of the Western Ontario and McMaster Universities Osteoarthritis Index scales. Patient interviews and a questionnaire that made use of a geriatric depression scale were conducted for the purpose of assessing depressive disorders. Regression analyses were performed to assess the relative contributions by radiographic severity and depression severity to Western Ontario and McMaster Universities Osteoarthritis Index scores and to explore any associations between radiographic severity and the presence of a depressive disorder with regard to the risk of symptomatic knee osteoarthritis. Symptomatic knee osteoarthritis was defined as a Western Ontario and McMaster Universities Osteoarthritis Index score of ≥39. The presence of a depressive disorder was found to be associated with an increased risk of symptomatic knee osteoarthritis (odds ratio = 5.87 [95% confidence interval, 3.01 to 11.44]). However, the influence of the presence of a depressive disorder was limited to subjects with a radiographic severity of minimal to moderate (Kellgren-Lawrence grade 0 to 3). The presence of a depressive disorder was not associated with the risk of symptomatic knee osteoarthritis in subjects with severe osteoarthritis (Kellgren-Lawrence grade 4). This study indicates that the assessment and management of coexisting depression should be integrated with the assessment and management of knee osteoarthritis, particularly when radiographic changes of osteoarthritis in the knee joint are not severe.

Total knee arthroplasty 2010

The Bone and Joint Decade from 2000 to 2010 has almostreached his end. The decade was invited by the UnitedNation and the World Health Organisation in order toincrease the awareness to people with musculoskeletaldiseases. The rapid increase in the prevalence of osteoar-thritis will have a growing impact on the health care andpublic health care system.It has been estimated that the number of patients diag-nosed with osteoarthritis will increase by 40% in the next25 years. The number of patients with symptomaticosteoarthritis has grown from 21 to 27 Million in the USAbetween 1995 and 2005 [4]. There are several reasons forthis development. First, the world population is currentlyincreasing from 6 Billion in 2000 to almost 7 Billion in2010 [8]. Thus, there will be more patients in the futuresuffering on osteoarthritis. The second major reason seemsto be the aging of our world population. It has been esti-mated, that the number of people over an age of 60 will risefrom one-fifth in 1995 to one-fourth in 2020, which meansan increase of about 40% in this group of age.Murphy et al. [6] estimated the lifetime risk of symp-tomatic knee osteoarthritis of about 45%. Many of thesepatients will be potential candidates for joint replacement.Disability and pain are the major indications for total kneearthroplasty. Nowadays people getting more demandingand want to be mobile and maintain their level of activityas long as possible. According to the Swedish kneearthroplasty register the average age of the patients hasdropped for total knee arthroplasty (TKA) from 72 to 69and for unicompartmental knee arthroplasty (UKA) evendown to 64 between 1995 until 2005. Based on these factsit is not surprising that the cost for total joint replacement ispermanently rising and exceeds in the United Statesalready 1% of the gross domestic product in 2007.The number of both primary and revision arthroplastywill increase about 300% in the next 15 years. Especiallydue to hip and knee arthroplasty the quality of life can besignificantly improved and many of the patients return to alevel of activities which makes them physically active andhappy in their older days [1].Nevertheless, not all of the patients will do perfectlywell. The success rate after TKA has been reportedbetween 80 and 90%. Going into more detail the satisfac-tion rate in pain relief varies between 72 and 86% and forspecific activities like getting in and out a car or bus (70%)or ascending stairs (73%) [5]. In order to find the cause forpersistent knee pain after TKA may sometimes be verydifficult. A new diagnostic algorithm to evaluate painfulknees after TKA has been introduced by Hirschmann andco-authors [3], in the current issue. They report about acombination of both single photon emission tomographyand conventional computerized tomography. This tech-nique allows the analysis of the component position byusing the reconstructed 3D-scan. In addition it will provideinformation about the bone metabolic status around theknee too. However, further studies are required in order tofind out whether this tool will be useful and specific enoughin patients with unexplained pain following TKA on aregular basis.Despite the improvement of diagnostic tools we have toimprove our understanding of the complexity of the kneeby further anatomical and kinematic studies as well. Itincludes the understanding for the natural knee kinematics

Case–control study of knee osteoarthritis and lifestyle factors considering their interaction with physical workload

The aim of this study is to examine the dose-response relationships between age, "lifestyle factors" (body mass index, tobacco smoking, sports), and symptomatic knee osteoarthritis in a population-based case-control study. Additionally, the study aims to investigate the mode of interaction between body mass index (BMI) and physical workload (occupational kneeling/squatting and lifting/carrying of loads) with respect to the risk of symptomatic knee osteoarthritis. In five orthopedic clinics and five practices, 295 male patients aged 25-70 with radiographically confirmed knee osteoarthritis associated with chronic complaints were recruited. The control group comprised 327 male control subjects. In a structured personal interview, body weight at different ages, body height, cumulative amount of smoking, and cumulative duration of different sports activities until the date of first diagnosis of knee osteoarthritis were elicited. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis. An interaction analysis for the parameters BMI and kneeling/squatting respective lifting/carrying of loads was performed. Population attributable risks (PAR) for knee osteoarthritis were determined for BMI solely and for the combination of BMI with occupational kneeling/squatting and lifting/carrying of loads, respectively. Age and overweight were strongly associated with the diagnosis of knee osteoarthritis. Compared with persons less than 35 years old, persons who were at least 65 years old had an odds ratio (OR) of 19.0 (95% CI 6.1-58.7) for knee osteoarthritis. Persons with a BMI > or = 28.41 kg/m2 had a strongly elevated risk of knee osteoarthritis (OR 10.8; 95% CI 4.8-24.3) compared to persons with a BMI < 22.86 kg/m2. Heavy tobacco smoking (> or = 55.5 pack years) was associated with a decreased knee osteoarthritis risk in comparison with never-smoking (OR 0.2; 95% CI 0.1-0.5). Ball games (handball, volleyball, basketball) and cycling were associated with symptomatic knee osteoarthritis (OR 4.0; 95% CI 1.8-8.9 and OR 3.7; 95% CI 1.7-7.8 in the highest category of cumulative duration, respectively); to a weaker degree jogging, swimming, and soccer also were positively related to symptomatic knee osteoarthritis. Combining the two parameters, BMI and kneeling/squatting into one variable led to a multiplicative interaction mode for symptomatic knee osteoarthritis. For persons with elevated BMI in combination with moderate to high exposure to occupational kneeling/squatting, the population attributable risk (PAR) was 4%. The PAR for elevated BMI in combination with moderate to high exposure to occupational lifting/carrying of loads was 7%. In accordance with the literature, we find a strong association between BMI and knee osteoarthritis risk. Considering the relatively high prevalence of occupational manual materials handling, prevention of knee osteoarthritis should not only focus on body weight reduction, but should also take into account work organizational measures particularly aiming to reduce occupational lifting and carrying of loads.

012 RISK FOR SYMPTOMATIC KNEE OSTEOARTHRITIS DOES NOT VARY BY KNEE EXTENSOR STRENGTH AND KNEE JOINT POSITION SENSE

011 – Figure 1 012 RISK FOR SYMPTOMATIC KNEE OSTEOARTHRITIS DOES NOT VARY BY KNEE EXTENSOR STRENGTH AND KNEE JOINT POSITION SENSE N.A. Segal1, N.A. Glass1, D. Felson2, M. Hurley3, M. Yang2, M. Nevitt4, C.E. Lewis5, J.C. Torner1 1Univ. of Iowa, Iowa City, IA; 2Boston Univ., Boston, MA; 3King’s Coll. London, London, United Kingdom; 4Univ. of California at San Francisco, San Francisco, CA; 5Univ. of Alabama at Birmingham, Birmingham, AL Purpose: Quadriceps weakness and impaired knee joint position sense (proprioception) have been linked cross-sectionally with knee OA. While neither of these factors has been independently associated with new onset disease, it is possible that one substitutes for the other and that only when both are impaired is the joint at risk. This study investigated whether sensoriomotor dysfunction the combination of quadriceps weakness and impaired knee joint position sense precedes development of symptomatic knee OA. Methods: The Multicenter Knee Osteoarthritis (MOST) Study is a longitudinal, observational study of adults age 50-79 years with knee OA or at high risk for knee OA. MOST subjects were excluded if they had symptomatic knee OA at baseline. Those with missing data or knee pain that interfered with strength testing were also excluded. Subjects underwent bilateral, weight bearing, fixedflexion radiographs, right knee joint reposition tests, and isokinetic knee extensor strength assessments; completed the Physical Activity Scale for the Elderly (PASE) and WOMAC questionnaires; and had height, and weight measurements taken. Symptomatic knee OA was defined as the combination of knee OA (KL grade ≥2) and frequent knee pain or stiffness at follow-up. The relationship between combinations of the tertiles of sex-specific baseline peak KES and tertiles of JPS and development of incident symptomatic knee OA at 30-month follow-up was evaluated with logistic regression adjusted for age, BMI, knee injury, knee surgery, and PASE score. Secondary analyses defined joint position sense as (1) the subject-specific variance over the 10 trials and (2) the average joint position sense over the 10 trials, and also assessed the interaction of knee extensor strength and joint position sense in predicting the outcome using generalized linear models. Results: 1565 subjects (911 women and 654 men) met eligibility criteria and were included in this study. The mean±SD age was 62.1±8.0 years, BMI was 29.8±5.4kg/m2, PASE score was 182.9±88.7, and WOMAC pain subscale was 2.2±2.8. There S16 Oral Presentations was no association between the combinations of knee extensor strength and joint position sense and incident symptomatic knee OA at 30-month follow-up. Secondary analyses, also did not demonstrate a statistically significant relationship between the interaction of knee extensor strength and either the average joint position sense or the variance in joint position sense and the development of incident symptomatic knee OA (all p>.25). Relationship Between Tertiles of Strength-Proprioception and Incident Symp-

Lifetime risk of symptomatic knee osteoarthritis

To estimate the lifetime risk of symptomatic knee osteoarthritis (OA), overall and stratified by sex, race, education, history of knee injury, and body mass index (BMI). The lifetime risk of symptomatic OA in at least 1 knee was estimated from logistic regression models with generalized estimating equations among 3,068 participants of the Johnston County Osteoarthritis Project, a longitudinal study of black and white women and men age >or=45 years living in rural North Carolina. Radiographic, sociodemographic, and symptomatic knee data measured at baseline (1990-1997) and first followup (1999-2003) were analyzed. The lifetime risk of symptomatic knee OA was 44.7% (95% confidence interval [95% CI] 40.0-49.3%). Cohort members with history of a knee injury had a lifetime risk of 56.8% (95% CI 48.4-65.2%). Lifetime risk rose with increasing BMI, with a risk of 2 in 3 among those who were obese. Nearly half of the adults in Johnston County will develop symptomatic knee OA by age 85 years, with lifetime risk highest among obese persons. These current high risks in Johnston County may suggest similar risks in the general US population, especially given the increase in 2 major risk factors for knee OA, aging, and obesity. This underscores the immediate need for greater use of clinical and public health interventions, especially those that address weight loss and self-management, to reduce the impact of having knee OA.

Weight loss reduces the risk for symptomatic knee osteoarthritis in women. The Framingham Study.

To evaluate the effect of weight loss in preventing symptomatic knee osteoarthritis in women. Cohort analytic study. The Framingham Study, based on a sample of a defined population. Women who participated in the Framingham Knee Osteoarthritis Study (1983 to 1985): Sixty-four out of 796 women studied had recent-onset symptomatic knee osteoarthritis (knee symptoms plus radiographically confirmed osteoarthritis) were compared with women without disease. Recalled date of symptom onset was used as the incident date of disease. Historical weight was defined as baseline body mass index up to 12 years before symptom onset. Change in body mass index was assessed at several intervals before the current examination. Odds ratios assessing the association between weight change and knee osteoarthritis were adjusted for age, baseline body mass index, history of previous knee injury, habitual physical activity level, occupational physical labor, smoking status, and attained education. Weight change significantly affected the risk for the development of knee osteoarthritis. For example, a decrease in body mass index of 2 units or more (weight loss, approximately 5,1 kg) over the 10 years before the current examination decreased the odds for developing osteoarthritis by over 50% (odds ratio, 0.46; 95% Cl, 0.24 to 0.86; P = 0.02). Among those women with a high risk for osteoarthritis due to elevated baseline body mass index (greater than or equal to 25), weight loss also decreased the risk (for 2 units of body mass index, odds ratio, 0.41; P = 0.02). Weight gain was associated with a slightly increased risk for osteoarthritis, which was not statistically significant. Weight loss reduces the risk for symptomatic knee osteoarthritis in women.