Cohort profile: Worldwide Collaboration on OsteoArthritis prediCtion for the Hip (World COACH) - an international consortium of prospective cohort studies with individual participant data on hip osteoarthritis

PURPOSE

Hip osteoarthritis (OA) is a major cause of pain and disability worldwide. Lack of effective therapies may reflect poor knowledge on its aetiology and risk factors, and result in the management of end-stage hip OA with costly joint replacement. The Worldwide Collaboration on OsteoArthritis prediCtion for the Hip (World COACH) consortium was established to pool and harmonise individual participant data from prospective cohort studies. The consortium aims to better understand determinants and risk factors for the development and progression of hip OA, to optimise and automate methods for (imaging) analysis, and to develop a personalised prediction model for hip OA.

PARTICIPANTS

World COACH aimed to include participants of prospective cohort studies with ≥200 participants, that have hip imaging data available from at least 2 time points at least 4 years apart. All individual participant data, including clinical data, imaging (data), biochemical markers, questionnaires and genetic data, were collected and pooled into a single, individual-level database.

FINDINGS TO DATE

World COACH currently consists of 9 cohorts, with 38 021 participants aged 18-80 years at baseline. Overall, 71% of the participants were women and mean baseline age was 65.3±8.6 years. Over 34 000 participants had baseline pelvic radiographs available, and over 22 000 had an additional pelvic radiograph after 8-12 years of follow-up. Even longer radiographic follow-up (15-25 years) is available for over 6000 of these participants.

FUTURE PLANS

The World COACH consortium offers unique opportunities for studies on the relationship between determinants/risk factors and the development or progression of hip OA, by using harmonised data on clinical findings, imaging, biomarkers, genetics and lifestyle. This provides a unique opportunity to develop a personalised hip OA risk prediction model and to optimise methods for imaging analysis of the hip.

Effect of weight loss on knee joint synovitis over 48 months and mediation by subcutaneous fat around the knee: data from the Osteoarthritis Initiative

BACKGROUND

Obesity influences the development of osteoarthritis via low-grade inflammation. Progression of local inflammation (= synovitis) increased with weight gain in overweight and obese women compared to stable weight. Synovitis could be associated with subcutaneous fat (SCF) around the knee. Purpose of the study was to investigate the effect of weight loss on synovitis progression and to assess whether SCF around the knee mediates the relationship between weight loss and synovitis progression.

METHODS

We included 234 overweight and obese participants (body mass index [BMI] ≥ 25 kg/m2) from the Osteoarthritis Initiative (OAI) with > 10% weight loss (n = 117) or stable overweight (< ± 3% change, n = 117) over 48 months matched for age and sex. In magnetic resonance imaging (MRI) at baseline and 48 months, effusion-synovitis and Hoffa-synovitis using the MRI Osteoarthritis Knee Score (MOAKS) and average joint-adjacent SCF (ajSCF) were assessed. Odds-ratios (ORs) for synovitis progression over 48 months (≥ 1 score increase) were calculated in logistic regression models adjusting for age, sex, baseline BMI, Physical Activity Scale for the Elderly (PASE), and baseline SCF measurements. Mediation of the effect of weight loss on synovitis progression by local SCF change was assessed.

RESULTS

Odds for effusion-synovitis progression decreased with weight loss and ajSCF decrease (odds ratio [OR] = 0.61 and 0.56 per standard deviation [SD] change, 95% confidence interval [CI] 0.44, 0.83 and 0.40, 0.79, p = 0.002 and 0.001, respectively), whereas odds for Hoffa-synovitis progression increased with weight loss and ajSCF decrease (OR = 1.47 and 1.48, CI 1.05, 2.04 and 1.02, 2.13, p = 0.024 and 0.038, respectively). AjSCF decrease mediated 39% of the effect of weight loss on effusion-synovitis progression.

CONCLUSIONS

Effusion-synovitis progression was slowed by weight loss and decrease in local subcutaneous fat. Hoffa-synovitis characterized by fluid in the infrapatellar fat pad increased at the same time, suggesting a decreasing fat pad rather than active synovitis. Decrease in local subcutaneous fat partially mediated the systemic effect of weight loss on synovitis.

Mediating Effect of Pain Sensitization on the Paradoxical Relation of Taking Opioids to Pain Severity in Knee Osteoarthritis: The Multicenter Osteoarthritis Study

OBJECTIVE

One of the less understood adverse effects while taking opioids is the paradoxical increase in pain, known as opioid-induced hyperalgesia (OIH). We sought to determine whether pain sensitization mediates the relation of taking an opioid to pain severity in people with knee osteoarthritis (OA).

METHODS

We included participants in a National Institutes of Health-funded cohort study of people with or at risk of knee OA. Participants were categorized into opioid and nonopioid analgesic groups at baseline. Western Ontario McMaster Universities OA Index (WOMAC) pain two years later was assessed as the outcome. We used causal mediation analysis to assess the mediating role of pain sensitization, quantified by changes in pressure pain threshold (PPT) at the wrist and patella over two years, on the effect of taking an opioid on WOMAC pain two years later.

RESULTS

We included 296 participants who took opioids and 1,070 participants who took nonopioid analgesics. Compared with taking nonopioid analgesics, taking opioids was associated with greater pain two years later. This relation was mediated by 0.05- and 0.08-unit changes in wrist PPT (95% confidence interval [CI] 0.01-0.10) and patellar PPT (95% CI 0.02-0.14), respectively. When we assessed any worsening in WOMAC pain score over two years, taking opioids, compared with taking nonopioid analgesics, had 2% and 5% higher odds of experiencing any worsening pain mediated by changes in wrist PPT (95% CI 0.99-1.04) and patellar PPT (95% CI 1.01-1.09), respectively.

CONCLUSION

Pain sensitization had small mediating effects on the paradoxical phenomenon of OIH, suggesting that pain sensitization may not play a major role and/or that PPT is an inadequate tool to assess OIH.

Intra-Articular Mineralization on Computerized Tomography of the Knee and Risk of Cartilage Damage: The Multicenter Osteoarthritis Study

OBJECTIVE

Intra-articular (IA) mineralization may contribute to osteoarthritis (OA) structural progression. We studied the association of IA mineralization on knee computed tomography (CT) with cartilage damage worsening on knee magnetic resonance imaging (MRI), with a focus on location- and tissue-specific effects.

METHODS

Participants from the Multicenter Osteoarthritis Study with knee CT and MRI scans were included. Presence of IA mineralization on CT was defined as a Boston University Calcium Knee Score >0 anywhere in the knee. Cartilage worsening on MRI was defined as any increase in the MRI OA Knee Score, including incident damage. We evaluated the association of whole-knee, compartment-specific (ie, medial or lateral), and subregion-specific (ie, location-matched) IA mineralization at baseline with cartilage worsening at two years' follow-up in the corresponding locations using binomial regression with generalized estimating equations, adjusting for age, sex, and body mass index (BMI).

RESULTS

We included 1,673 participants (mean age 60 years, 56% female, mean BMI 29). Nine percent had any IA mineralization in the knee, and 47.4% had any cartilage worsening on follow-up. Mineralization of any tissue in the knee, regardless of location, was not associated with MRI cartilage worsening. However, cartilage mineralization was associated with 1.39 (95% confidence interval 1.04-1.88) times higher risk of cartilage worsening in the same compartment, with similar results in subregion-specific analysis.

CONCLUSION

CT-detected IA mineralization in the cartilage was associated with higher risk of MRI cartilage worsening in the same compartment and subregion over two years. These findings suggest potential localized, tissue-specific effects of IA mineralization on cartilage pathology in knee OA.

Exploring different models of pain phenotypes and their association with pain worsening in people with early knee osteoarthritis: The MOST cohort study

OBJECTIVE

To determine i) pain phenotypes (PP) in people with early-stage knee osteoarthritis (EKOA); ii) the longitudinal association between the phenotypes and pain worsening at two years.

DESIGN

We studied participants with EKOA from the Multicenter Osteoarthritis Study defined as pain intensity ≤3/10, Kellgren and Lawrence grade ≤2, intermittent pain none to sometimes, and no constant pain. Two models of PP were explored. Model A included pressure pain thresholds, temporal summation, conditioned pain modulation, pain catastrophizing, sleep quality, depression, and widespread pain (WSP). In Model B, gait characteristics, quadriceps strength, comorbidities, and magnetic resonance imaging features were added to Model A. Latent Class Analysis was used to create phenotypes, and logistic regression was used to determine their association with pain worsening.

RESULTS

750 individuals (60% females), mean age [standard deviation (SD)]: 60.3 (9.4) were included in Model A and 333 individuals (60% females), mean age (SD): 59.4 (8.1) in Model B. 3-class and 4-class solutions were chosen for Model A and Model B. In Model A, the most "severe" phenotype was dominated by psychosocial factors, WSP, and measures of nervous system sensitization. Similarly in Model B, the Model A phenotype plus gait variables, quadriceps strength, and comorbidities were dominant. Surprisingly, none of the phenotypes in either model had a significant relationship with pain worsening.

CONCLUSION

Phenotypes based upon various factors thought to be important for the pain experience were identified in those with EKOA but were not significantly related to pain worsening. These phenotypes require validation with clinically relevant endpoints.

Associations between anterior knee pain and 2-year patellofemoral cartilage worsening: The MOST study

OBJECTIVE

Anterior knee pain (AKP) is associated with patellofemoral osteoarthritis (PFOA), but longitudinal studies are lacking. If AKP precedes PFOA, it may create an opportunity to identify and intervene earlier in the disease process. The purpose of this study was to examine the longitudinal relation of AKP to worsening patellofemoral (PF) cartilage over two years.

DESIGN

Participants were recruited from the Multicenter Osteoarthritis Study, a longitudinal study of individuals with or at risk for knee osteoarthritis (OA). Exclusion criteria included bilateral knee replacements, arthritis other than OA, and radiographic PFOA. At baseline, participants completed a knee pain map questionnaire and underwent knee magnetic resonance imaging (MRI). Imaging was repeated at 2-year follow-up. Exposure was presence of frequent AKP. Outcome was worsening cartilage damage in the PF joint defined as increase in MRI Osteoarthritis Knee Score from baseline to 2 years. Log-binomial models were used to calculate risk ratios (RR).

RESULTS

One knee from 1083 participants (age 56.7 ± 6.6 years; body mass index 28.0 ± 4.9 kg/m2) was included. Frequent AKP and frequent isolated AKP were present at baseline in 14.5% and 3.6%, respectively. Frequent AKP was associated with an increased risk (RR: 1.78, 95% confidence interval: 1.21, 2.62) of 2-year worsening cartilage damage in the lateral PF compartment. No association was found between frequent AKP and worsening in the medial PF joint.

CONCLUSION

Frequent AKP at baseline was associated with worsening cartilage damage in the lateral PF joint over 2 years.

Relation of Intra-Articular Mineralization to Knee Pain in Knee Osteoarthritis: A Longitudinal Analysis in the MOST Study

OBJECTIVE

Intra-articular (IA) calcium crystal deposition is common in knee osteoarthritis (OA), but of unclear significance. It is possible that low-grade, crystal-related inflammation may contribute to knee pain. We examined the longitudinal relation of computed tomography (CT)-detected IA mineralization to the development of knee pain.

METHODS

We used data from the National Institutes of Health-funded longitudinal Multicenter Osteoarthritis Study. Participants had knee radiographs and bilateral knee CTs at baseline, and pain assessments every 8 months for 2 years. CT images were scored using the Boston University Calcium Knee Score. We longitudinally examined the relation of CT-detected IA mineralization to the risk of frequent knee pain (FKP), intermittent or constant knee pain worsening, and pain severity worsening using generalized linear mixed-effects models.

RESULTS

We included 2,093 participants (mean age 61 years, 57% women, mean body mass index 28.8 kg/m2 ). Overall, 10.2% of knees had IA mineralization. The presence of any IA mineralization in the cartilage was associated with 2.0 times higher odds of having FKP (95% confidence interval [CI] 1.38-2.78) and 1.86 times more frequent intermittent or constant pain (95% CI 1.20-2.78), with similar results seen for the presence of any IA mineralization in the meniscus or joint capsule. A higher burden of IA mineralization anywhere within the knee was associated with a higher odds of all pain outcomes (odds ratio ranged from 2.14 to 2.21).

CONCLUSION

CT-detected IA mineralization was associated with risk of having more frequent, persistent, and worsening knee pain over 2 years. Targeting IA mineralization may have therapeutic potential for pain improvement in knee OA.

Prevalence of intra-articular mineralization on knee computed tomography: the multicenter osteoarthritis study

OBJECTIVE

The aim of this work was to report the prevalence of computed tomography (CT)-detected intra-articular mineralization.

DESIGN

We included participants from the Multicenter Osteoarthritis (MOST) Study. At the 12th year visit of the MOST study, bilateral knee CTs were first obtained. All participants also had posteroanterior and lateral radiographs of bilateral knees and completed standard questionnaires. Knee radiographs were assessed for Kellgren & Lawrence grade (KLG) and radiographic evidence of intra-articular mineralization. CT images were scored using the Boston University Calcium Knee Score (BUCKS) for cartilage, menisci, ligaments, capsule, and vasculature. Prevalence of intra-articular mineralization was computed for the total sample, and stratified by age, sex, race, Body Mass Index (BMI), presence of frequent knee pain, and KLG. We also determined distribution of mineralization in the cartilage and meniscus, and co-localization.

RESULTS

4140 bilateral knees from 2070 participants were included (56.7% female, mean age 61.1 years, mean BMI: 28.8 kg/m2). On radiographs 240 knees (5.8%) had intraarticular mineralization, while CT-detected mineralization was present in 9.8% of knees. Prevalence of hyaline articular and meniscus mineralization increased with age and KL grade, and was similar by sex, BMI categories, and comparable in subjects with and without frequent knee pain. Mineralization tended to be ubiquitous in the joint, most commonly involving all three (medial/lateral tibiofemoral and patellofemoral) compartments (3.1%), while the patellofemoral compartment was the most involved compartment in isolation (1.4%).

CONCLUSIONS

CT of the knee provides greater visualization of intra-articular mineralization than radiographs and allows better localization of the crystal deposition within the joint. Further studies should focus on the co-localization of intra-articular crystal deposition and corresponding magnetic resonance imaging (MRI)-features of knee osteoarthritis (OA).

Development of a Magnetic Resonance Imaging-Based Definition of Knee Osteoarthritis: Data From the Multicenter Osteoarthritis Study

OBJECTIVE

Although magnetic resonance imaging (MRI) is the imaging modality of choice for research, there is no widely accepted MRI definition of knee osteoarthritis (OA). We undertook this study to test the performance of different MRI definitions of OA.

METHODS

We studied Multicenter Osteoarthritis Study participants with knee symptoms using posteroanterior and lateral knee radiographs and MRIs. Radiographic OA was defined as Kellgren/Lawrence grade ≥2 in the tibiofemoral (TF) and/or patellofemoral (PF) joint. Symptomatic OA was defined using a validated questionnaire. MRI findings of cartilage damage, osteophytes, bone marrow lesions (BMLs), and synovitis were scored using the Whole-Organ MRI Score system. We compared definitions using combinations of MRI features to the validation criteria of prevalent radiographic OA and symptomatic OA. All combinations included cartilage damage score ≥2 (0-6 scale) and osteophyte score ≥2 (0-6 scale); addition of BMLs and synovitis score was also tested. We also evaluated a Delphi panel definition that defined OA differently for the PF and TF joints. For each definition, we calculated sensitivity, specificity, and the area under the curve (AUC).

RESULTS

We included 1,185 knees from 1,185 participants (mean age 66 years, 62% female, 89% White). Among the 1,185 knees, 482 knees had radiographic OA, and 524 knees had symptomatic OA. The MRI definitions with a cartilage score ≥2 and osteophyte score ≥2 and definitions which added BMLs or synovitis score ≥1 had the highest sensitivities (95.2% and 94.5%, respectively) for prevalent radiographic OA (AUCs 0.67 and 0.69, respectively), and also had the highest sensitivities for symptomatic OA. The Delphi panel definition had similar performance but was more complex to apply.

CONCLUSION

An MRI OA definition requiring cartilage damage and a small osteophyte with or without BMLs or synovitis had the best performance and was simplest for identifying radiographic OA and symptomatic OA.

Post-surgical contributors to persistent knee pain following knee replacement: The Multicenter Osteoarthritis Study (MOST)

Objective

Pain persistence following knee replacement (KR) occurs in ∼20-30% of patients. Although several studies have identified preoperative risk factors for persistent post-KR pain, few have focused on post-KR contributing factors. We sought to determine whether altered nociceptive signaling and other peripheral nociceptive drivers present post-operatively contribute to post-KR pain.

Design

We included participants from the Multicenter Osteoarthritis Study who were evaluated ∼12 months after KR. We evaluated the relation of measures of pain sensitivity [pressure pain threshold (PPT), temporal summation (TS), and conditioned pain modulation (CPM)] and the number of painful body sites to post-KR WOMAC knee pain, and of the number of painful sites to altered nociceptive signaling using linear or logistic regression models, as appropriate.

Results

171 participants (mean age 69 years, 62% female) were included. TS was associated with worse WOMAC pain post-KR (β ​= ​0.77 95% CI:0.19-1.35) and reduced odds of achieving patient acceptable symptom state (aOR ​= ​0.54 95%CI:0.34-0.88). Inefficient CPM was also associated with worse WOMAC pain post-KR (β ​= ​1.43 95% CI:0.15-2.71). In contrast, PPT was not associated with these outcomes. The number of painful body sites present post-KR was associated with TS (β ​= ​0.05, 95% CI:0.01, 0.05).

Conclusions

Post-KR presence of central sensitization and inefficient descending pain modulation was associated with post-KR pain. We also noted that presence of other painful body sites contributes to altered nociceptive signaling, and this may thus also contribute to the experience of knee pain post-KR. Our findings provide novel insights into central pain mechanisms and other peripheral pain sources contributing to post-KR persistent knee pain.

The Association of Metabolic Syndrome and Obesity With Clinical Hip Osteoarthritis in the Study of Osteoporotic Fractures and the Osteoporotic Fractures in Men Study Cohorts

OBJECTIVE

Metabolic dysregulation frequently co-occurs with obesity, which has been shown to be a risk factor for lower extremity osteoarthritis (OA). We evaluated the association between metabolic syndrome (MetS), alone and in combination with obesity, and hip OA.

METHODS

In two parallel cross-sectional analyses, we studied 403 women from the Study of Osteoporotic Fractures (SOF) and 2354 men from the Osteoporotic Fractures in Men (MrOS) study. We used multivariable logistic regression to evaluate associations of obesity (body mass index ≥30 kg/m2 ) and/or MetS (three of five National Cholesterol Education Program Adult Treatment Panel III criteria) with clinical hip OA, defined as a modified Croft score of 2 or more or total hip replacement, and pain or limited range of motion. Our analysis adjusted for demographics.

RESULTS

Approximately 3.5% of SOF women and 5.4% of MrOS men had clinical hip OA. Among women, obesity was not associated with hip OA, yet those with MetS had a 365% higher odds of hip OA (95% CI: 1.37-15.83). Among men, those who had obesity had a 115% higher odds of hip OA (95% CI: 1.39-3.32), yet MetS was not associated with hip OA. There was no interaction between MetS, obesity, and hip OA in either women or men.

CONCLUSION

In women, but not in men, MetS was associated with hip OA. In men, but not in women, obesity was associated with hip OA. These findings suggest that mechanical effects of obesity may predominate in the pathogenesis of hip OA in men, whereas metabolic effects predominate in women.

Alkylresorcinol, a biomarker for whole grain intake, and its association with osteoarthritis: the MOST study

INTRODUCTION

Higher intake of fiber has been associated with lower risk of incident symptomatic osteoarthritis (OA). We examined whether levels of alkylresorcinol (AR), a marker of whole grain intake, were associated with OA in subjects in The Multicenter Osteoarthritis (MOST) Study.

METHOD

Knee x-rays and knee pain were assessed at baseline and through 60-months. Stored baseline fasting plasma samples were analyzed for AR homologues (C17:0, C19:0, C21:0, C23:0, C25:0) and total AR levels (AR sum). Two nested case-control studies, one for incident radiographic OA and one for incident symptomatic OA were performed with participants re-assessed at 15, 30 and 60 months. Multivariable conditional logistic regression with baseline covariates including age, sex, BMI, physical activity, quadriceps strength, race, smoking, depressive symptoms, diabetes and knee injury tested the association of log transformed AR levels with OA outcomes.

RESULTS

Seven hundred seventy-seven subjects were, on average, in their 60's, and most were women. For 60-month cumulative incidence, there was no significant association between quartiles of AR concentration and incident radiographic (e.g., for incident radiographic OA, highest vs lowest quartile of AR sum showed RR = 0.93 (95% CI 0.59, 1.47), and for symptomatic OA RR was 1.22 (95% CI 0.76, 1.94). In secondary analyses examining 30-month incidence, high AR levels were associated with a reduced risk of X-ray OA (RR = 0.31 (95% CI 0.15, 0.64).

CONCLUSION

In primary analyses, AR levels were not associated with risk of OA, but secondary analyses left open the possibility that high AR levels may protect against OA.

Depressive symptoms and multi-joint pain partially mediate the relationship between obesity and opioid use in people with knee osteoarthritis

OBJECTIVES

To assess the relation of obesity to opioid use in people with or at risk of knee osteoarthritis (OA), and the extent to which this association is mediated by number of painful joints or depressive symptoms.

METHODS

We used data from the Multicenter Osteoarthritis Study, a longitudinal cohort of older adults with or at risk of knee OA. Opioid use was identified by prescription medications and self-report. Obesity was defined as BMI ≥ 30 kg/m2. Multi-joint pain was assessed using a standardized body homunculus, and depressive symptoms using the Center for Epidemiological Studies Depression scale. We quantified the direct and indirect effect of obesity on opioid use through the number of painful joints or depressive symptoms using causal mediation analysis by natural-effects models.

RESULTS

We studied 2,335 participants (mean age: 68; mean BMI 31 kg/m2; 60% women). Persons with obesity had ∼50% higher odds of opioid use than those without. Estimates of indirect (mediated) effect by the number of painful joints and depressive symptoms suggested an increased odds of opioid use by 34% (odds ratio [OR] = 1.34, 95% CI: 1.04, 1.70) and 35% (OR 1.35, 95% CI: 1.05, 1.71), respectively, in obese vs non-obese individuals. The total effect of obesity on opioid use was higher in women than in men.

CONCLUSIONS

Multi-joint pain and depressive symptoms partially explained greater opioid use among obese persons with knee OA, demonstrating that the negative impact of obesity on knee OA extends beyond its influence on knee pain and structural progression.

Does weight-bearing versus non-weight-bearing pain reflect different pain mechanisms in knee osteoarthritis?: the Multicenter Osteoarthritis Study (MOST)

OBJECTIVE

Knee osteoarthritis (OA) is predominantly characterized by pain with weight-bearing activities. Pain at rest also occurs but the mechanisms for this are not clear. We evaluated the relations of nociceptive signal alterations to weight-bearing and non-weight-bearing pain in knee OA.

DESIGN

We used data from a NIH-funded longitudinal cohort of older adults with or at risk of knee OA. We evaluated quantitative sensory testing (QST) measures (pressure pain threshold (PPT) at patellae and the wrist; mechanical temporal summation (TS); conditioned pain modulation (CPM)). Each WOMAC pain question was dichotomized as having at least moderate pain, and we further categorized them as weight-bearing pain and non-weight-bearing pain. We evaluated the relation of QST measures to each pain outcome using logistic regression, adjusting for potential confounders.

RESULTS

2,749 participants (5,479 knees) were included (mean age 64 ± 11, 57% female). Each SD unit decrease in patellar PPT was associated with greater odds of both weight-bearing pain (OR 1.51 (95% CI 1.27, 1.79)) and non-weight-bearing pain (OR 1.46 (1.20-1.77)), while wrist PPT was associated with greater odds of weight-bearing pain (OR 1.27 (1.15, 1.39)) but only with pain during sitting/lying (OR 1.20 (1.01, 1.43)). TS was significantly associated with greater odds of pain with walking and stairs (OR 1.11 (1.01, 1.23), 1.11 (1.03, 1.20), respectively). CPM was not associated with any pain outcomes.

CONCLUSIONS

Our findings challenge the hypothesis that non-weight-bearing pain may reflect greater pain sensitization and/or inefficient CPM than weight-bearing pain in knee OA, suggesting other mechanisms are likely responsible.

Recreational Physical Activity and Risk of Incident Knee Osteoarthritis: An International Meta-Analysis of Individual Participant-Level Data

OBJECTIVE

The effect of physical activity on the risk of developing knee osteoarthritis (OA) is unclear. We undertook this study to examine the relationship between recreational physical activity and incident knee OA outcomes using comparable physical activity and OA definitions.

METHODS

Data were acquired from 6 global, community-based cohorts of participants with and those without knee OA. Eligible participants had no evidence of knee OA or rheumatoid arthritis at baseline. Participants were followed up for 5-12 years for incident outcomes including the following: 1) radiographic knee OA (Kellgren-Lawrence [K/L] grade ≥2), 2) painful radiographic knee OA (radiographic OA with knee pain), and 3) OA-related knee pain. Self-reported recreational physical activity included sports and walking/cycling activities and was quantified at baseline as metabolic equivalents of task (METs) in days per week. Risk ratios (RRs) were calculated and pooled using individual participant data meta-analysis. Secondary analysis assessed the association between physical activity, defined as time (hours per week) spent in recreational physical activity and incident knee OA outcomes.

RESULTS

Based on a total of 5,065 participants, pooled RR estimates for the association of MET days per week with painful radiographic OA (RR 1.02 [95% confidence interval (95% CI) 0.93-1.12]), radiographic OA (RR 1.00 [95% CI 0.94-1.07]), and OA-related knee pain (RR 1.00 [95% CI 0.96-1.04]) were not significant. Similarly, the analysis of hours per week spent in physical activity also showed no significant associations with all outcomes.

CONCLUSION

Our findings suggest that whole-body, physiologic energy expenditure during recreational activities and time spent in physical activity were not associated with incident knee OA outcomes.

Progression of Knee Osteoarthritis With Use of Intraarticular Glucocorticoids Versus Hyaluronic Acid

OBJECTIVE

To determine whether intraarticular glucocorticoid (GC) injections are associated with increased knee osteoarthritis (OA) progression compared to hyaluronic acid (HA) injections, which have been reported to delay OA progression and knee replacement.

METHODS

We identified participants from 2 large cohort studies, the Osteoarthritis Initiative (OAI) and the Multicenter Osteoarthritis Study. Study visits were performed at regular intervals and included questionnaires about intraarticular GC or HA injection use in the previous 6 months and incident total knee replacement (TKR). Knee radiographs were obtained at each study visit and interpreted in a similar manner. Outcome measures were radiographic progression based on Kellgren/Lawrence (K/L) grade and joint space narrowing (JSN) for both cohorts and based on medial joint space width for OAI participants, and incident TKR. We compared preinjection and postinjection radiographs to generate rate ratios of progression comparing GC injection with HA injection. A Cox proportional hazards model was used to estimate the rate of TKR for both groups.

RESULTS

We studied 791 participants (980 knees) with knee OA, of whom 629 reported GC injection use and 162 HA injection use. Rate ratios of progression were similar between those receiving GCs and those receiving HA for JSN (1.00 [95% confidence interval (95% CI) 0.83-1.21]), K/L grade (1.03 [95% CI 0.83-1.29]), and medial joint space width (1.03 [95% CI 0.72-1.48]). Hazard of TKR was slightly lower for those receiving intraarticular GC compared to those receiving HA (hazard ratio 0.75 [95% CI 0.51-1.09]).

CONCLUSION

Intraarticular GC injections are not associated with an increased risk of knee OA progression compared to HA.

Association of Pain Sensitization and Conditioned Pain Modulation to Pain Patterns in Knee Osteoarthritis

OBJECTIVE

To examine the cross-sectional association of ascending pain mechanisms, implicated in pain sensitization, and descending pain modulation with pain patterns and unpredictability of pain.

METHODS

The Multicenter Osteoarthritis Study is a longitudinal cohort of older adults with or at risk of knee osteoarthritis. Peripheral and central ascending pain mechanisms were assessed using quantitative sensory tests, pressure pain thresholds using a handheld pressure algometer (knee/peripheral and wrist/central), and temporal summation using weighted probes (wrist/central). Descending modulation was assessed by conditioned pain modulation using pressure pain thresholds and a forearm ischemia test. Pain patterns were characterized based on responses to the Intermittent and Constant Osteoarthritis Pain questionnaire: 1) no intermittent or constant pain, 2) intermittent pain only, 3) constant pain only, and 4) combined constant and intermittent pain. A question regarding frequency assessed unpredictable pain. We assessed the association of quantitative sensory test measures to pain patterns using regression models with generalized estimating equations.

RESULTS

There were 2,794 participants (mean age 63.9 years, body mass index 29.5 kg/m² , and 57% female). Lower pain sensitization by wrist pressure pain threshold (odds ratio [OR] 0.80 [95% confidence interval (95% CI) 0.68, 0.93]) and adequate conditioned pain modulation (OR 1.45 [95% CI 1.10, 1.92]) were associated with having constant ± intermittent pain compared with intermittent pain only. Higher pain sensitization (by pressure pain thresholds and temporal summation) was associated with a higher likelihood of unpredictable pain.

CONCLUSION

Knee pain patterns appear to be related to peripheral ± central facilitated ascending pain mechanisms and descending modulatory mechanisms. These findings highlight the need for a broader approach to understanding pain mechanisms by symptomatic disease progression.

Factors associated with pain resolution in those with knee pain: the MOST study

OBJECTIVES

To determine how many persons with knee pain have subsequent pain resolution and what factors are associated with resolution, focusing especially on types of physical activity.

METHODS

Using data from MOST, an NIH funded longitudinal cohort study of persons with or at risk of knee osteoarthritis, we studied participants who at baseline reported knee pain on most days at both a telephone interview and clinic visit. We defined pain resolution if at 30 and 60 month exams, they reported no knee pain on most days and compared these participants to those who reported persistent pain later. In logistic regression analyses, we examined the association of baseline risk factors including demographic factors, BMI, depressive symptoms, isokinetic quadriceps strength and both overall physical activity (using the PASE survey) and specific activities including walking, gardening, and different intensities of recreational activities with pain resolution.

RESULTS

Of 1,304 participants with knee pain on most days at baseline, 265 (20.3%) reported no knee pain at 30 and 60 months. Lower BMI and stronger quadriceps were associated with higher odds of pain resolution while overall physical activity was not. Of activities, walking decreased the odds of pain resolution (adjOR = 0.86 (95% CI 0.76, 0.98)), but gardening (adjOR = 1.59 (1.16, 2.18)) and moderate intensity recreational activities ((adjOR = 1.24 (1.05, 1.46)) increased it.

CONCLUSION

Pain resolution is common in those with knee pain. Factors increasing the odds of pain resolution include lower BMI, greater quadriceps strength and gardening and moderately intensive recreational activities.

Appendicular Lean Mass, Grip Strength, and the Development of Knee Osteoarthritis and Knee Pain Among Older Adults

Objective

The association of sarcopenia with development of knee osteoarthritis (OA) or knee pain in older adults is uncertain. We examined the relationship of grip strength and appendicular lean mass (ALM) with the likelihood of developing knee OA and knee pain in older adults in the Health ABC (Health, Aging, and Body Composition) Study.

Methods

ALM and grip strength were assessed at baseline by dual‐energy x‐ray absorptiometry and handheld dynamometry, respectively. Incident clinically diagnosed, symptomatic knee OA, defined as new participant report of physician‐diagnosed knee OA and concurrent frequent knee pain, and incident frequent knee pain over 5 years of follow‐up were examined. Separate regression analyses, stratified by sex, modeled associations of baseline ALM and grip strength with the likelihood of incident clinically diagnosed, symptomatic knee OA and incident knee pain over follow‐up, adjusting for covariates.

Results

Among the 2779 subjects without OA at baseline, 95 men (6.9%) and 158 women (11.3%) developed clinically diagnosed, symptomatic knee OA, and, among the 2182 subjects without knee pain at baseline, 315 men (28.3%) and 385 women (36.1%) developed knee pain over follow‐up. Among men only, each SD decrement of ALM was associated with decreasing likelihood of incident knee OA (odds ratio [OR] per SD decrement: 0.68; 95% confidence interval [CI]: 0.47‐0.97), and each SD decrement of grip strength was associated with increasing likelihood of incident knee pain (OR per SD decrement: 1.20; 95% CI: 1.01‐1.42).

Conclusion

In older men, ALM and grip strength may be associated with the development of knee OA and knee pain, respectively.

Association of Intermittent and Constant Knee Pain Patterns With Knee Pain Severity and With Radiographic Knee Osteoarthritis Duration and Severity

OBJECTIVE

To examine the relation of knee pain patterns to pain severity and to radiographic osteoarthritis (OA) severity and duration.

METHODS

The Multicenter Osteoarthritis Study is a longitudinal cohort of older adults with or at risk of knee OA. Participants' Intermittent and Constant Osteoarthritis Pain (ICOAP) scores were characterized as 1) no intermittent or constant pain, 2) intermittent pain only, 3) constant pain only, and 4) a combination of constant and intermittent pain. Knee pain severity was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale and a visual analog scale (VAS). Radiographic knee OA (ROA) severity was defined as Kellgren/Lawrence grade ≥2, and ROA duration was defined according to the clinic visit at which ROA was first noted. We assessed the relation of ICOAP pain patterns to knee pain severity, ROA severity, and ROA duration using regression models with generalized estimating equations.

RESULTS

There were 2,322 participants (mean age 68.8 years, body mass index 31.0 kg/m² , 60% female). Higher ICOAP pain patterns, i.e., a mix of constant and intermittent pain, were associated with greater WOMAC pain severity compared with those patients without either pain pattern (odds ratio [OR] 43.2 [95% confidence interval (95% CI) 26.4-61.3]). Results were similar for the VAS (OR 71.2 [95% CI 45.7-110.9]). Those patients with more severe and longer duration of ROA were more likely to have a mix of constant and intermittent pain compared with those without either pain (OR 3.7 [95% CI 3.1-4.6] and OR 2.9 [95% CI 2.5-3.5], respectively).

CONCLUSION

Knee pain patterns are associated with radiographic disease stage and duration, as well as pain severity, highlighting the fact that pain patterns are important for understanding symptomatic disease progression.

Association between current medication use and progression of radiographic knee osteoarthritis: data from the Osteoarthritis Initiative

Objective

Use of specific medications may accelerate the progression of radiographic knee OA (RKOA). Our aim was to examine the effect of medication use on the progression of RKOA.

Methods

We used longitudinal data from the Osteoarthritis Initiative (OAI), an observational study of risk factors for knee OA. At baseline, we selected participants with RKOA (Kellgren–Lawrence grade ≥2) and excluded those with a history of knee-related injury/surgery and other musculoskeletal disorders. Current medication use (use/non-use in the previous 30 days) and radiographic medial minimum joint space width (mJSW) data were available at baseline and annually up to 96 months follow-up. We used random effects, panel regression to assess the association between current medication use (non-users as reference group) and change in mJSW.

Results

Of 2054 eligible participants, 2003 participants with baseline mJSW data were included [55.7% female, mean age 63.3 (s.d. 8.98) years]. Of seven medication classes, at baseline NSAIDs were the most frequently used analgesia (14.7%), anti-histamine (10.4%) use was frequent and the following comorbidity medications were used most frequently: statins (27.4%), anti-hypertensives (up to 15.0%), anti-depressant/anxiolytics/psychotropics (14.0%), osteoporosis-related medication (10.9%) and diabetes-related medication (6.9%). Compared with current non-users, current use of NSAIDs was associated with a loss of mJSW (b = −0.042, 95% CI −0.08, −0.0004). No other associations were observed.

Conclusions

In current users of NSAIDs, mJSW loss was increased compared with current non-users in participants with RKOA. Clinical trials are required to assess the potential disease-modifying effects of these medications.

Obese and overweight individuals have greater knee synovial inflammation and associated structural and cartilage compositional degeneration: data from the osteoarthritis initiative

OBJECTIVE

This work aims to study (i) the relationship between body mass index (BMI) and knee synovial inflammation using non-contrast-enhanced MRI and (ii) the association of synovial inflammation versus degenerative abnormalities and pain.

MATERIALS AND METHODS

Subjects with risk for and mild to moderate radiographic osteoarthritis were selected from the Osteoarthritis Initiative. Subjects were grouped into three BMI categories with 87 subjects per group: normal weight (BMI, 20-24.9 kg/m²), overweight (BMI, 25-29.9 kg/m²), and obese (BMI, ≥ 30 kg/m²), frequency matched for age, sex, race, Kellgren-Lawrence grade, and history of knee surgery and injury. Semi-quantitative synovial inflammation imaging biomarkers were obtained including effusion-synovitis, size and intensity of infrapatellar fat pad signal abnormality, and synovial proliferation score. Cartilage composition was measured using T₂ relaxation time and structural abnormalities using the whole-organ magnetic resonance imaging score (WORMS). The Western Ontario and McMasters (WOMAC) Osteoarthritis Index was used for pain assessment. Intra- and inter-reader reproducibility was assessed by kappa values.

RESULTS

Overweight and obese groups had higher prevalence and severity of all synovial inflammatory markers (p ≤ 0.03). Positive associations were found between synovial inflammation imaging biomarkers and average T₂ values, WORMS maximum scores and total WOMAC pain scores (p < 0.05). Intra- and inter-reader kappa values for imaging biomarkers were high (0.76-1.00 and 0.60-0.94, respectively).

CONCLUSION

Being overweight or obese was significantly associated with a greater prevalence and severity of synovial inflammation imaging biomarkers. Substantial reproducibility and high correlation with knee structural, cartilage compositional degeneration, and WOMAC pain scores validate the synovial inflammation biomarkers used in this study.

Predominant lifetime occupation and associations with painful and structural knee osteoarthritis: An international participant-level cohort collaboration

Objective

With adults working to older ages, occupation is an important, yet less modifiable domain of physical activity to consider in the risk of knee osteoarthritis (OA). This study aimed to investigate the association between predominant lifetime occupation and prevalent knee OA.

Design

Participant-level data were used from five international community-based cohorts: Johnston County Osteoarthritis Project, the Hertfordshire Cohort Study, the Multicenter Osteoarthritis Study, the Tasmanian Cohort Study and Framingham Osteoarthritis Study. Self-reported predominant occupation was categorized into sedentary, light, light manual and heavy manual levels. Cross-sectional associations between predominant lifetime occupation and knee OA outcomes including prevalence of radiographic knee OA (RKOA), symptomatic RKOA and knee pain, were assessed using logistic regression, accounting for cohort clustering.

Results

Data for 7391 participants were included. 24.7% reported sedentary lifetime occupation, 30.0% light, 35.9% light manual and 9.4% heavy manual. 43.3% presented with RKOA, 52.1% with knee pain and 29.0% with symptomatic RKOA. There was over a two-fold increase in the odds of having RKOA, knee pain and symptomatic RKOA in those whose with heavy manual compared to sedentary occupations ((odds ratio (OR): 2.14; 95% confidence interval (CI): 1.79, 2.58), (OR: 2.19; 95% CI: 1.78, 2.70), (OR: 2.41; 95% CI: 1.94, 2.99) respectively).

Conclusion

This large international multi-cohort study demonstrated an association of heavy manual work with RKOA, symptomatic RKOA and knee pain. Measures that protect workers and are designed to reduce heavy manual related activities remain a priority to reduce the risk of knee OA.

Varus alignment of the proximal tibia is associated with structural progression in early to moderate varus osteoarthritis of the knee

PURPOSE

Lower limb malalignment is a strong predictor of progression in knee osteoarthritis. The purpose of this study is to identify the individual alignment variables that predict progression in early to moderate osteoarthritis of the knee.

METHOD

A longitudinal cohort study using data from the Osteoarthritis Initiative. In total, 955 individuals (1329 knees) with early to moderate osteoarthritis (Kellgren-Lawrence grade 1, 2 or 3) were identified. All subjects had full-limb radiographs analysed using the Osteotomy module within Medicad^® Classic (Hectec GMBH) to give a series of individual alignment variables relevant to the coronal alignment of the lower limb. Logistic regression models, with generalised estimating equations were used to identify which of these individual alignment variables predict symptom worsening (WOMAC score > 9 points) and or structural progression (joint space narrowing progression in the medial compartment > 0.7mm) over 24 months.

RESULTS

Individual alignment variable were associated with both valgus and varus alignment (mechanical Lateral Distal Femoral Angle, Medial Proximal Tibial Angle and mechanical Lateral Distal Tibial Angle). Only the Medial Proximal Tibial Angle was significantly associated with structural progression and none of the variables was associated with symptom progression. The odds of joint space narrowing progression in the medial compartment occurring at 24 months increased by 21% for every one degree decrease (more varus) in Medial Proximal Tibial Angle (p < 0.001) CONCLUSIONS: Our results suggest that the risk of structural progression in the medial compartment is associated with greater varus alignment of the proximal tibia.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Sleep Quality Is Related to Worsening Knee Pain in Those with Widespread Pain: The Multicenter Osteoarthritis Study

OBJECTIVE

We examined the association between sleep and odds of developing knee pain, and whether this relationship varied by status of widespread pain (WSP).

METHODS

At the 60-month visit of the Multicenter Osteoarthritis Study, sleep quality and restless sleep were each assessed by using a single item from 2 validated questionnaires. Each sleep measure was categorized into 3 levels, with poor/most restless sleep as the reference. WSP was defined as pain above and below the waist on both sides of the body and axially using a standard homunculus, based on the American College of Rheumatology criteria. Outcomes from 60-84 months included (1) knee pain worsening (KPW; defined as minimal clinically important difference in WOMAC pain), (2) prevalent, and (3) incident consistent frequent knee pain. We applied generalized estimating equations in multivariable logistic regression models.

RESULTS

We studied 2329 participants (4658 knees; 67.9 yrs, body mass index 30.9]. We found that WSP modified the relationship between sleep quality and KPW (p = 0.002 for interaction). Among persons with WSP, OR (95% CI) for KPW was 0.53 (0.35-0.78) for those with very good sleep quality (p trend < 0.001); additionally, we found the strongest association of sleep quality in persons with > 8 painful joint sites (p trend < 0.01), but not in those with ≤ 2 painful joint sites. Similar results were observed using restless sleep, in the presence of WSP. The cross-sectional relationship between sleep and prevalence of consistent frequent knee pain was significant.

CONCLUSION

Better sleep was related to less KPW with coexisting widespread pain.

Reliability of a new scoring system for intraarticular mineralization of the knee: Boston University Calcium Knee Score (BUCKS)

BACKGROUND

The role of intra-articular mineralization in osteoarthritis (OA) is unclear. Its understanding may potentially advance our knowledge of knee OA pathogenesis. We describe and assess the reliability of a novel computed tomography (CT) scoring system, the Boston University Calcium Knee Score (BUCKS) for evaluating intra-articular mineralization.

METHODS

We included subjects from the most recent study visit of the Multicenter Osteoarthritis Study (MOST) Study, a NIH-funded longitudinal cohort of community-dwelling older adults with or at risk of knee OA. All subjects underwent CT of bilateral knees. Each knee was scored at 28 scored locations (14 for cartilage, 6 for menisci, 6 for ligaments, 1 for joint capsule, and 1 popliteal-tibial vessels). A single musculoskeletal radiologist scored cartilage and meniscus subregions, as well as vascular calcifications assigning to each a score ranging from 0 to 3. The joint capsule, medial and lateral posterior meniscal roots, anterior cruciate ligament (ACL)/posterior cruciate ligament (PCL) and 2 collateral ligaments [medial collateral ligament (MCL)/lateral collateral ligament (LCL)] were each scored 0 or 1 for absence or presence of mineralization. To assess reliability, 31 subject CTs were reread 12 weeks later by the same reader and by a second reader and agreement was evaluated using a weighted kappa.

RESULTS

The intra-reader reliability ranged from 0.92 for ligaments to 1.0 for joint capsule. The inter-reader reliability ranged from 0.94 for cartilage and ligaments, to 1.0 for joint capsule.

CONCLUSION

BUCKS demonstrated excellent reliability and is a potentially useful CT-based tool for studying the role of calcium crystals in knee OA.

Predictors of a change in patient willingness to have Total knee arthroplasty: Insights from the osteoarthritis initiative

BACKGROUND

While many factors have been shown to influence patient willingness to have total joint arthroplasty, factors associated with changes in patient willingness to have arthroplasty have not been studied. The objective of this research is to identify predictors of change in patient willingness to have total knee arthroplasty (TKA).

METHODS

Patient willingness to have TKA as well as questionnaire, clinical, and radiographic data, were obtained from the Osteoarthritis Initiative (OAI) for individuals with, or at high risk for developing knee OA. Mixed effects ordinal logistic regressions were employed to assess the relationships between 40 predictors and change in willingness to have surgery. Predictors significant in univariate models were included in a multivariable analysis.

RESULTS

Three thousand three hundred and ninety-four OAI patients were included in our analysis. Between baseline and follow-up, 462 (13.6%) became more willing and 533 (15.7%) became less willing to have TKA. After controlling for demographic factors in multivariable analysis, patients with higher income and expected difficulty with postoperative walking were more likely to increase their willingness to have TKA. General health, race, and knee injections within the past six months approached significance with regard to increasing willingness to have TKA over time.

CONCLUSION

Income and expectations of difficulty walking postoperatively were significantly associated with changes in patient willingness to have TKA independent of age, sex, health coverage, employment, marriage status, and knee pain. Understanding factors influencing patient willingness to have surgery may be instrumental in counseling and addressing the mismatch of OA disease burden to surgical utilization.

Association of Visceral Adiposity With Pain but Not Structural Osteoarthritis

OBJECTIVE

Osteoarthritis (OA) and pain are both made more severe by low-grade inflammation. This study was undertaken to examine whether visceral fat, a major source of inflammatory cytokines and adipokines, is associated with an increased risk of knee OA or musculoskeletal pain.

METHODS

Subjects in the Multicenter Osteoarthritis Study cohort, who were age 50-79 years and had or were at high risk of knee OA, underwent whole-body dual x-ray absorptiometry (DXA) at baseline. At baseline, 30 months, and 60 months radiographs and magnetic resonance images (MRIs) of the knees were obtained, and patients were asked to score the severity of their knee pain and to identify sites of joint pain using a body homunculus. Baseline DXA scans were used to measure total body fat and visceral and subcutaneous fat in the torso. The association of fat depot size with structural outcomes (incident radiographic OA and cartilage loss and synovitis on MRI) and with pain outcomes (worsening knee pain, number of painful joints, and widespread pain) was assessed. Regression analyses were adjusted for age, sex, race, education level, smoking status, physical activity, body mass index (BMI), and depressive symptoms.

RESULTS

Of the 2,961 participants at baseline, 60.7% were women. The mean age was 62.5 years and mean BMI was 30.5 kg/m² . After adjustment for covariates, no fat measures were associated with any structural outcomes. However, total and visceral, but not subcutaneous, fat were positively associated with worsening knee pain (P = 0.0005 for total fat and P = 0.007 for visceral fat) and widespread pain (P = 0.001 for total fat and P = 0.02 for visceral fat), and the amount of visceral fat was associated with the number of painful joints (P = 0.07).

CONCLUSION

Our findings indicate that visceral fat is associated with an increased risk of musculoskeletal and widespread pain.

Examining Timeliness of Total Knee Replacement Among Patients with Knee Osteoarthritis in the U.S.: Results from the OAI and MOST Longitudinal Cohorts

BACKGROUND

Patients with knee osteoarthritis may undergo total knee replacement too early or may delay or underuse this procedure. We quantified these categories of total knee replacement utilization in 2 cohorts of participants with knee osteoarthritis and investigated factors associated with each category.

METHODS

Data were pooled from 2 multicenter cohort studies that collected demographic, patient-reported, radiographic, clinical examination, and total knee replacement utilization information longitudinally on 8,002 participants who had or were at risk for knee osteoarthritis and were followed for up to 8 years. Validated total knee replacement appropriateness criteria were longitudinally applied to classify participants as either potentially appropriate or likely inappropriate for total knee replacement. Participants were further classified on the basis of total knee replacement utilization into 3 categories: timely (indicating that the patient had total knee replacement within 2 years after the procedure had become potentially appropriate), potentially appropriate but knee not replaced (indicating that the knee had remained unreplaced for >2 years after the procedure had become potentially appropriate), and premature (indicating that the procedure was likely inappropriate but had been performed). Utilization rates were calculated, and factors associated with each category were identified.

RESULTS

Among 8,002 participants, 3,417 knees fulfilled our inclusion and exclusion criteria and were classified into 1 of 3 utilization categories as follows: 290 knees (8% of the total and 9% of the knees for which replacement was potentially appropriate) were classified as "timely", 2,833 knees (83% of the total and 91% of those for which replacement was potentially appropriate) were classified as "potentially appropriate but not replaced", and 294 knees (comprising 9% of the total and 26% of the 1,114 total knee replacements performed) were considered to be "likely inappropriate" yet underwent total knee replacement and were classified as "premature". Of the knees that were potentially appropriate but were not replaced, 1,204 (42.5%) had severe symptoms. Compared with the patients who underwent timely total knee replacement, the likelihood of being classified as potentially appropriate but not undergoing total knee replacement was greater for black participants and the likelihood of having premature total knee replacement was lower among participants with a body mass index of >25 kg/m and those with depression.

CONCLUSIONS

In 2 multicenter cohorts of patients with knee osteoarthritis, we observed substantial numbers of patients who had premature total knee replacement as well as of patients for whom total knee replacement was potentially appropriate but had not been performed >2 years after it had become potentially appropriate. Further understanding of these observations is needed, especially among the latter group.

CLINICAL RELEVANCE

Undergoing total knee replacement too early may result in little or no benefit while exposing the patient to the risks of a major operation, whereas waiting too long may cause limitations in physical activity that in turn increase the risk of additional disability and chronic disease; however, little is known about timing of this surgery. We quantified the extent of premature, timely, and delayed use, and found a high prevalence of both premature and delayed use.

Brief Report: Leg Length Inequality and Hip Osteoarthritis in the Multicenter Osteoarthritis Study and the Osteoarthritis Initiative

OBJECTIVE

Studies suggest that persons with a leg length inequality (LLI) of ≥2 cm have an increased risk of developing knee osteoarthritis (OA) in that limb. The present study was undertaken to examine whether LLI also confers an increased risk of hip OA.

METHODS

Using long limb radiographs from subjects in the Multicenter Arthritis Study (MOST) and the Osteoarthritis Initiative (OAI), we measured LLI and scored hip radiographs that were obtained at baseline and 3-5-year follow-up. The associations of LLI of ≥1 cm and LLI of ≥2 cm with radiographic hip OA were examined cross-sectionally and longitudinally, assessing risk in shorter limbs and longer limbs compared to limbs from subjects with no LLI. We carried out logistic regression analyses with generalized estimating equations and adjusted for age, sex, body mass index, height, and cohort of origin.

RESULTS

There were 1,966 subjects from the MOST and 2,627 subjects from the OAI. Twelve percent had LLI of ≥1 cm and 1% had LLI of ≥2 cm. For LLI ≥1 cm, the adjusted odds ratio for prevalent hip OA in the shorter leg was 1.47 (95% confidence interval [95% CI] 1.07-2.02) and for LLI ≥2 cm, it was 2.15 (95% CI 0.87-5.34). For LLI ≥1 cm, the odds of incident hip OA in the shorter leg were 1.39 (95% CI 0.81-2.39) while for LLI ≥2 cm, they were 4.20 (95% CI 1.26-14.03). We found no increased risk of hip OA in longer limbs.

CONCLUSION

Our findings suggest that, as with knee OA, legs that are at least 2 cm shorter than the contralateral leg are at increased risk of hip OA.

Development and validation of risk stratification trees for incident slow gait speed in persons at high risk for knee osteoarthritis

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.

Pain Susceptibility Phenotypes in Those Free of Knee Pain With or at Risk of Knee Osteoarthritis: The Multicenter Osteoarthritis Study

OBJECTIVE

It is not clear why some individuals develop pain with knee osteoarthritis (OA). We undertook this study to identify pain susceptibility phenotypes (PSPs) and their relationship to incident persistent knee pain (PKP) 2 years later.

METHODS

We identified individuals free of PKP from the Multicenter Osteoarthritis Study, a longitudinal cohort of older adults with or at risk of knee OA. Latent class analysis was used to determine PSPs that may contribute to development of PKP apart from structural pathology. These included widespread pain, poor sleep, and psychological factors as well as pressure pain threshold and temporal summation (TS) as determined by quantitative sensory testing (QST). We used logistic regression to evaluate the association of sociodemographic factors with PSPs and the relationship of PSPs to the development of PKP over 2 years.

RESULTS

A total of 852 participants were included (mean age 67 years, body mass index 29.5 kg/m² , 55% women). Four PSPs were identified, primarily characterized by varying proportions (low/absent, moderate, or high) of the presence of pressure pain sensitivity and of facilitated TS, reflecting different measures of sensitization. Subjects in the PSP with a high proportion of pressure pain sensitivity and a moderate proportion of facilitated TS were twice as likely to develop incident PKP over 2 years (odds ratio 1.98 [95% confidence interval 1.07-3.68]) compared with subjects in the PSP having a low proportion of sensitization by both measures.

CONCLUSION

Four PSPs were identified, 3 of which were predominated by QST evidence of sensitization and 1 of which was associated with developing PKP 2 years later. Prevention or amelioration of sensitization may be a novel approach to preventing onset of PKP in OA.

Risk of Knee Osteoarthritis With Obesity, Sarcopenic Obesity, and Sarcopenia

OBJECTIVE

Obesity, defined by anthropometric measures, is a well-known risk factor for knee osteoarthritis (OA), but there is a relative paucity of data regarding the association of body composition (fat and muscle mass) with risk of knee OA. We undertook this study to examine the longitudinal association of body composition categories based on fat and muscle mass with risk of incident knee OA.

METHODS

We included participants from the Multicenter Osteoarthritis Study, a longitudinal cohort of individuals with or at risk of knee OA. Based on body composition (i.e., fat and muscle mass) from whole-body dual x-ray absorptiometry, subjects were categorized as obese nonsarcopenic (obese), sarcopenic obese, sarcopenic nonobese (sarcopenic), or nonsarcopenic nonobese (the referent category). We examined the relationship of baseline body composition categories with the risk of incident radiographic OA at 60 months using binomial regression with robust variance estimation, adjusting for potential confounders.

RESULTS

Among 1,653 subjects without radiographic knee OA at baseline, significantly increased risk of incident radiographic knee OA was found among obese women (relative risk [RR] 2.29 [95% confidence interval {95% CI} 1.64-3.20]), obese men (RR 1.73 [95% CI 1.08-2.78]), and sarcopenic obese women (RR 2.09 [95% CI 1.17-3.73]), but not among sarcopenic obese men (RR 1.74 [95% CI 0.68-4.46]). Sarcopenia was not associated with risk of knee OA (for women, RR 0.96 [95% CI 0.62-1.49]; for men, RR 0.66 [95% CI 0.34-1.30]).

CONCLUSION

In this large longitudinal cohort, we found body composition-based obesity and sarcopenic obesity, but not sarcopenia, to be associated with risk of knee OA. Weight loss strategies for knee OA should focus on obesity and sarcopenic obesity.

Does the intensity of daily walking matter for protecting against the development of a slow gait speed in people with or at high risk of knee osteoarthritis? An observational study

OBJECTIVE

Knee osteoarthritis (OA) is a risk factor for a decline in gait speed. Daily walking reduces the risk of developing slow gait speed and future persistent functional limitation. However, the protective role of walking intensity is unclear. We investigated the association of substituting time spent not walking, with walking at light and moderate-to-vigorous intensities for incident slow gait over 2-years, among people with or at high risk of knee OA.

METHOD

We used baseline and 2-year follow-up data from the Multicenter Osteoarthritis (MOST) study (n = 1731) and the Osteoarthritis Initiative (OAI, n = 1925). Daily walking intensity was objectively assessed using accelerometer-enabled devices, and classified as; not walking (<1 steps/min), very-light (1-49 steps/min), light (50-100 steps/min), and moderate-to-vigorous (>100 steps/min). We defined slow gait during a 20-m walk, as <1 m/s and <1.2 m/s. Isotemporal substitution evaluated time-substitution effects on incident slow gait outcomes at 2-years.

RESULTS

Replacing 20 min/day of not walking with walking at a moderate-to-vigorous intensity, demonstrated small to moderate reductions in the risk of developing a gait speed <1.0 m/s (Relative Risk [95% confidence interval (CI)]; MOST = 0.51 [0.27, 0.98], OAI = 0.21 [0.04, 0.98]), and <1.2 m/s (MOST = 0.73 [0.53, 1.00], OAI = 0.65 [0.36, 1.18]). However, only risk reductions for <1.0 m/s met statistical significance. Replacing not walking with very-light or light intensity walking was not associated with the risk of developing slow gait outcomes.

CONCLUSION

When possible, walking at a moderate-to-vigorous intensity (>100 steps/min) may be best recommended in order to reduce the risk of developing critical slow gait speed among people with, or at high risk of knee OA.

Harmonising measures of knee and hip osteoarthritis in population-based cohort studies: an international study

OBJECTIVE

Population-based osteoarthritis (OA) cohorts provide vital data on risk factors and outcomes of OA, however the methods to define OA vary between cohorts. We aimed to provide recommendations for combining knee and hip OA data in extant and future population cohort studies, in order to facilitate informative individual participant level analyses.

METHOD

International OA experts met to make recommendations on: 1) defining OA by X-ray and/or pain; 2) compare The National Health and Nutrition Examination Survey (NHANES)-type OA pain questions; 3) the comparability of the Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC) scale to NHANES-type OA pain questions; 4) the best radiographic scoring method; 5) the usefulness of other OA outcome measures. Key issues were explored using new analyses in two population-based OA cohorts (Multicenter Osteoarthritis Study; MOST and Osteoarthritis Initiative OAI).

RESULTS

OA should be defined by both symptoms and radiographs, with symptoms alone as a secondary definition. Kellgren and Lawrence (K/L) grade ≥2 should be used to define radiographic OA (ROA). The variable wording of pain questions can result in varying prevalence between 41.0% and 75.4%, however questions where the time anchor is similar have high sensitivity and specificity (91.2% and 89.9% respectively). A threshold of 3 on a 0-20 scale (95% CI 2.1, 3.9) in the WOMAC pain subscale demonstrated equivalence with the preferred NHANES-type question.

CONCLUSION

This research provides recommendations, based on expert agreement, for harmonising and combining OA data in existing and future population-based cohorts.

Relation of meniscus pathology to prevalence and worsening of patellofemoral joint osteoarthritis: the Multicenter Osteoarthritis Study

OBJECTIVE

To determine the relationship of meniscal damage to magnetic resonance imaging (MRI) features of compartment-specific patellofemoral joint (PFJ) osteoarthritis (OA) at baseline and 2 years later.

METHOD

Individuals from a prospective cohort of individuals aged 50-79 with or at risk of knee OA were included. At the 60-month and 84-month study visit, Whole-Organ MRI Score (WORMS) was used to assess meniscal tears and extrusions as well as cartilage damage and bone marrow lesions (BMLs) in the medial and lateral patella and trochlea. Worsening of structural features was defined as any increase in WORMS score from 60 to 84 months. Logistic regression was used to determine the cross-sectional and longitudinal relation of meniscus damage to features of compartment-specific PFJ OA.

RESULTS

Relative to knees without lateral meniscal pathology at baseline, those with grades 3-4 lateral meniscal tear and extrusion had greater risk of worsening of cartilage damage in the lateral PFJ 2 years later (Risk ratio: 1.7 [95% CI: 1.1-2.7) and (1.7 [1.2-2.5]), respectively. Relative to those without medial meniscal pathology at baseline, those with grades 1-2 (0.6 [0.4-0.9]) and 3-4 (0.7 [0.5-1.0]) medial meniscal tears had lower risk of worsening of BMLs in the medial PFJ 2 years later.

CONCLUSION

Meniscal tear and extrusion are associated with increased risk of medial and lateral PFJ OA and more severe meniscal pathology is associated with worsening of PFJ OA 2 years later. Lateral meniscal pathology appears to be more detrimental to the lateral PFJ.

Predictive Validity of Radiographic Trabecular Bone Texture in Knee Osteoarthritis: The Osteoarthritis Research Society International/Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium

OBJECTIVE

To evaluate radiographic subchondral trabecular bone texture (TBT) as a predictor of clinically relevant osteoarthritis (OA) progression (combination of symptom and structural worsening).

METHODS

The Foundation for the National Institutes of Health (FNIH) OA Biomarkers Consortium undertook a study of progressive knee OA cases (n = 194 knees with both radiographic and pain progression over 24-48 months) and comparators (n = 406 OA knees not meeting the case definition). TBT parameters were extracted from a medial subchondral tibial region of interest by fractal signature analysis of radiographs using validated semiautomated software. Baseline TBT and time-integrated values over 12 and 24 months were evaluated for association with case status and separately with radiographic and pain progression status, adjusted for age, sex, body mass index, race, baseline Kellgren/Lawrence grade, baseline joint space width, Western Ontario and McMaster Universities Osteoarthritis Index pain score, and pain medication use. C statistics were generated from receiver operating characteristic curves.

RESULTS

Relative to comparators, cases were characterized by thinner vertical and thicker horizontal trabeculae. The summed composite of 3 TBT parameters at baseline and over 12 and 24 months best predicted case status (odds ratios 1.24-1.43). The C statistic for predicting case status using the TBT composite score (0.633-0.649) was improved modestly but statistically significantly over the use of covariates alone (0.608). One TBT parameter, reflecting thickened horizontal trabeculae in cases, at baseline and over 12 and 24 months, predicted risk of any progression (radiographic and/or pain progression).

CONCLUSION

Although associations are modest, TBT could be an attractive means of enriching OA trials for progressors since it can be generated from screening knee radiographs already standard in knee OA clinical trials.

Varus Thrust and Incident and Progressive Knee Osteoarthritis

OBJECTIVE

To determine if varus thrust, a bowing out of the knee during gait (i.e., the first appearance or worsening of varus alignment during stance), is associated with incident and progressive knee osteoarthritis (OA), we undertook an Osteoarthritis Initiative ancillary study. We further considered hypothesized associations adjusted for static alignment, anticipating some attenuation.

METHODS

Gait was observed for the presence of thrust by 1 of 2-3 examiners per study site at 4 sites. In eligible knees, incident OA was defined as subsequent incident Kellgren/Lawrence grade ≥2, whole- and partial-grade medial joint space narrowing (JSN), and annualized loss of joint space width (JSW); progression was defined as medial JSN and JSW loss. Outcome measures were assessed for up to 7 years of follow-up. Analyses were knee-level, using multivariable logistic and linear regression with generalized estimating equations to account for between-limb correlation.

RESULTS

The incident OA sample included 4,187 knees (2,610 persons); the progression sample included 3,421 knees (2,284 persons). In knees with OA, thrust was associated with progression as assessed by each outcome measure, with adjustment for age, sex, body mass index, and pain on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale. In knees without OA, varus thrust was not associated with incident OA or other outcomes. After adjustment for alignment, the thrust-progression association was attenuated, but an independent association persisted for partial-grade JSN and JSW loss outcome models. WOMAC pain and alignment were consistently associated with all outcome measures. Within the stratum of varus knees, thrust was associated with an increased risk of progression.

CONCLUSION

Varus thrust visualized during gait is associated with knee OA progression and should be a target of intervention development.

Relationship of knee pain to time in moderate and light physical activities: Data from Osteoarthritis Initiative

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.

Associations of Musculoskeletal Pain With Mobility in Older Adults: Potential Cerebral Mechanisms

BACKGROUND

Musculoskeletal pain is highly prevalent and limits mobility in older adults. A potential mechanism by which pain affects mobility could be through its negative impact on the brain. We examined whether structural integrity of cerebral gray and white matter (WM) mediated the relationship between pain and mobility in community-dwelling older adults.

METHODS

Musculoskeletal pain, gait speed, and neuroimaging data were obtained concurrently from the Health ABC study (mean age = 83/56% female, n = 212). Microstructural gray matter integrity was measured by mean diffusivity (MD), WM microstructure and macrostructure were measured by fractional anisotropy (FA) and WM hyperintensities (WMH), respectively. Regression models were adjusted for gray matter atrophy, age, gender, medication use, and obesity. Bootstrapped mediation methods were used (1,000 bootstrapped samples, 95% confidence intervals).

RESULTS

The associations of musculoskeletal pain with WMH (β = .19, p < .05) and FA (β = -.18, p < .05) were robust to adjustment for gender, medication use, age, body mass index (BMI), and brain atrophy. Participants who experienced both knee and back pain had a significantly slower gait speed (~0.11 m/s) than those without knee or back pain (p < .05) independent of gender, medication, age, and BMI. WMH and FA significantly mediated the pain-gait speed relationship. Associations between pain and MD were not significant, and MD did not modify the association between pain and gait speed.

CONCLUSIONS

Cerebral WM integrity may contribute to the detrimental effects of musculoskeletal pain on mobility, although pre-existing WM integrity may also simultaneously amplify pain and decrease mobility. Future studies are needed to further understand whether successful pain management may significantly improve both brain health and mobility.

Multiple Nonspecific Sites of Joint Pain Outside the Knees Develop in Persons With Knee Pain

OBJECTIVE

Many persons with knee pain have joint pain outside the knee, but despite the impact and high frequency of this pain, its distribution and causes have not been studied. We undertook this study to test the hypothesis of those studying gait abnormalities who have suggested that knee pain causes pain in adjacent joints but that pain adaptation strategies are highly individualized.

METHODS

We studied persons ages 50-79 years with or at high risk of knee osteoarthritis who were recruited from 2 community-based cohorts, the Multicenter Osteoarthritis Study and the Osteoarthritis Initiative, and we followed them up for 5-7 years. We excluded those with knee pain at baseline and compared those who had developed knee pain at the first follow-up examination (the index visit) with those who had not. We examined pain on most days at joint regions outside the knee in examinations after the index visit. Logistic regression analyses examined the risk of joint-specific pain adjusted for age, sex, body mass index, and symptoms of depression, and we performed sensitivity analyses excluding those with widespread pain.

RESULTS

In the combined cohorts, 693 persons had knee pain at the index visit and 2,793 did not. A total of 79.6% of those with bilateral knee pain and 63.8% of those with unilateral knee pain had pain during follow-up in a joint region outside the knee, compared with 49.9% of those without knee pain. There was an increased risk of pain at most extremity joint sites, without a predilection for specific sites. Results were unchanged when those with widespread pain were excluded.

CONCLUSION

Persons with chronic knee pain are at increased risk of pain in multiple joints in no specific pattern.

Knee tissue lesions and prediction of incident knee osteoarthritis over 7 years in a cohort of persons at higher risk

OBJECTIVE

Among high risk individuals, whether knee lesions in tissues involved in osteoarthritis (OA) can improve prediction of knee OA is unclear. We hypothesized that models predicting (1) incident osteophytes and (2) incident osteophytes and joint space narrowing can be improved by including symptoms or function, and further improved by lesion status.

DESIGN

In Osteoarthritis Initiative (OAI) participants with normal knee X-rays, we assessed cartilage damage, bone marrow lesions (BMLs), and menisci. Cox proportional hazards models were used to develop risk prediction models for risk of each outcome. Nested models (increasingly larger baseline covariable sets) were compared using likelihood ratio tests and Schwarz Bayesian Information Criterion (SBC). Model discrimination used receiver operating characteristic (ROC) curves and area under the curve (AUC).

RESULTS

In 841 participants [age 59.6, body mass index (BMI) 26.7, 55.9% women] over up to 7 years follow-up, each larger set improved prediction (+hand OA, injury, surgery, activities; +symptoms/function). Prediction was further improved by including cartilage damage both compartments, BMLs both compartments, meniscal tear, meniscal extrusion, sum of lesion types, number of subregions with cartilage damage, number of subregions with BMLs, and (concurrently) subregion number with cartilage damage, subregion number with BMLs, and meniscal tear. AUCs were ≥0.80 for both outcomes for number of subregions with cartilage damage and the combined model.

CONCLUSIONS

Among persons at higher risk for knee OA with normal X-rays, MRI tissue lesions improved prediction of mild as well as moderate disease. These findings support that disease onset is likely occurring during the "high-risk" period and encourage a reorientation of approach.

Knee Pain and Structural Damage as Risk Factors for Incident Widespread Pain: Data From the Multicenter Osteoarthritis Study

OBJECTIVE

To examine the longitudinal relationship of knee pain, radiographic osteoarthritis (OA), symptomatic knee OA, and knee pain severity to incident widespread pain.

METHODS

The Multicenter Osteoarthritis Study is a longitudinal cohort of persons with or at risk of knee OA. Participants were characterized as having consistent frequent knee pain, radiographic OA (Kellgren/Lawrence scale grade ≥2), symptomatic OA, and knee pain severity at the 60-month visit (baseline). Widespread pain was categorized as pain above and below the waist, on both sides of the body and axially, using a standard homunculus, excluding knee pain. Incident widespread pain was defined as the presence of widespread pain at 84 months in those who were free of widespread pain at baseline. We assessed the relationship of baseline radiographic OA, symptomatic OA, consistent frequent knee pain, and knee pain severity, respectively, with incident widespread pain using logistic regression, adjusting for potential confounders, including models with and without pain severity.

RESULTS

At baseline, 1,129 subjects were eligible for analysis (mean ± SD age 66.7 ± 7.8 years; mean ± SD body mass index 30.1 ± 5.8 kg/m² ; 52% women). Radiographic OA in either knee (adjusted odds ratio [OR_adj ] 0.90 [95% confidence interval (95% CI) 0.63-1.30]; P = 0.587) was not associated with incident widespread pain. Baseline bilateral consistent frequent knee pain (OR_adj 2.35 [95% CI 1.37-4.03]), bilateral symptomatic OA (OR_adj 2.11 [95% CI 1.04-4.24]), and knee pain severity (worst knee) (OR_adj 1.11 [95% CI 1.05-1.17]; P < 0.001) were significantly associated with incident widespread pain.

CONCLUSION

Consistent frequent knee pain, symptomatic OA, and knee pain severity increased the risk of developing widespread pain, independently of structural pathology. These results suggest that knee pain, and not structural pathology, contributes to the onset of widespread pain.

Modeling the shape and composition of the human body using dual energy X-ray absorptiometry images

There is growing evidence that body shape and regional body composition are strong indicators of metabolic health. The purpose of this study was to develop statistical models that accurately describe holistic body shape, thickness, and leanness. We hypothesized that there are unique body shape features that are predictive of mortality beyond standard clinical measures. We developed algorithms to process whole-body dual-energy X-ray absorptiometry (DXA) scans into body thickness and leanness images. We performed statistical appearance modeling (SAM) and principal component analysis (PCA) to efficiently encode the variance of body shape, leanness, and thickness across sample of 400 older Americans from the Health ABC study. The sample included 200 cases and 200 controls based on 6-year mortality status, matched on sex, race and BMI. The final model contained 52 points outlining the torso, upper arms, thighs, and bony landmarks. Correlation analyses were performed on the PCA parameters to identify body shape features that vary across groups and with metabolic risk. Stepwise logistic regression was performed to identify sex and race, and predict mortality risk as a function of body shape parameters. These parameters are novel body composition features that uniquely identify body phenotypes of different groups and predict mortality risk. Three parameters from a SAM of body leanness and thickness accurately identified sex (training AUC = 0.99) and six accurately identified race (training AUC = 0.91) in the sample dataset. Three parameters from a SAM of only body thickness predicted mortality (training AUC = 0.66, validation AUC = 0.62). Further study is warranted to identify specific shape/composition features that predict other health outcomes.

The relationship between meniscal pathology and osteoarthritis depends on the type of meniscal damage visible on magnetic resonance images: data from the Osteoarthritis Initiative

OBJECTIVE

To determine the association of different types of meniscal pathology with knee pain, bone marrow lesion (BML) volume, and end-stage knee osteoarthritis (esKOA).

DESIGN

Participants were selected from an ancillary project to the Osteoarthritis Initiative (OAI) who had at least one knee with symptomatic osteoarthritis. Baseline magnetic resonance images (MRI) were evaluated for meniscal pathology using a modified International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine (ISAKOS) classification system. We collapsed 10 types of meniscal pathology into five categories: normal, intrameniscal signal, morphological deformity/extrusion (altered meniscal shape and/or extrusion but no apparent substance loss), tear, and maceration. Outcomes included Western Ontario and McMaster Universities osteoarthritis index (WOMAC) knee pain and BML volume at baseline and after 2 years. We defined the prevalence of esKOA based on a validated algorithm. We performed logistic regression and adjusted for age, sex, and body mass index (BMI).

RESULTS

The 463 participants (53% male) included in the analysis had mean age 63 (9.2) years, BMI 29.6 (4.6) kg/m², and 71% had Kellgren-Lawrence grade ≥2. Morphological deformity/extrusion and maceration, but no other types of meniscal pathology, were associated with BML volume (morphological deformity/extrusion odds ratio [OR] = 2.47, 95% CI: 1.49, 4.09, maceration OR = 5.85, 95% CI: 3.40, 10.06) and change in BML volume (morphological deformity/extrusion OR = 2.17, 95% CI: 1.37, 3.45, maceration OR = 3.12, 95% CI: 1.87, 5.19). Only maceration was associated with baseline WOMAC knee pain (OR = 2.82, 95% CI: 1.79, 4.43) and prevalence of esKOA (OR = 7.53, 95% CI: 4.25, 13.31).

CONCLUSIONS

Based on MRI, morphologic deformity/extrusion and maceration rather than intrameniscal signal or tear were associated with osteoarthritis severity and progression, which highlights the importance of differentiating distinct types of meniscal pathology.

Association of Serum Klotho with Loss of Bone Mineral Density and Fracture Risk in Older Adults

OBJECTIVES

Klotho deficiency has been previously linked to aging-like phenotypes such as osteoporosis, cognitive impairment, and sarcopenia. Low serum klotho was shown to be related to grip strength and disability. Nonetheless, no previous study has explored the association between serum klotho and fractures. The purpose of this report is to examine the relationship of serum klotho with bone mineral density (BMD) loss and fractures in older adults.

DESIGN

The Health, Aging, and Body Composition (Health ABC) Study is a longitudinal cohort study of 3,075 community-dwelling older adults.

SETTING

US clinical centers.

PARTICIPANTS

Two thousand seven hundred and seventy six well-functioning black and white adults aged 70 to 79 years with serum klotho measurements were followed up for a median of 5 years.

MEASUREMENTS

Percent annualized BMD change and fracture risk were compared across klotho quartiles. A Poisson distribution was used to calculate age-adjusted fracture incidence rates, and Cox proportional hazards models for multivariable-adjusted hazard ratios.

RESULTS

The annualized percent changes in hip, femoral neck, and vertebral BMD were similar across klotho quartiles. Participants experienced 507 nonspine fractures, 203 hip fractures, and 135 vertebral fractures. The Incidence rate (IR) of nonspine fractures was 17 per 1,000 person-years. The most frequent site was hip (IR = 6 per 1,000 person-years) and the IR of vertebral fractures was 3 per 1,000 person-years. There was no association between the lowest quartile of plasma klotho and nonspine (hazard ratio (HR) = 1.19, 95% confidence interval (CI) = 0.86-1.65), hip (HR = 1.34, 95% CI = 0.79-2.27), or vertebral fractures (HR = 1.17, 95% CI = 0.65-2.11).

CONCLUSION

Although klotho gene is a susceptible gene for reduced BMD, klotho blood concentration does not appear to be a predictor of bone loss or fracture risk in well-functioning older adults.

Exploratory analysis of osteoarthritis progression among medication users: data from the Osteoarthritis Initiative

BACKGROUND

We conducted an exploratory analysis of osteoarthritis progression among medication users in the Osteoarthritis Initiative to identify interventions or pathways that may be associated with disease modification and therefore of interest for future clinical trials.

METHODS

We used participants from the Osteoarthritis Initiative with annual medication inventory data between the baseline and 36-month follow-up visit (n = 2938). Consistent medication users were defined for each medication classification as a participant reporting at all four annual visits that they were regularly using an oral prescription medication at the time of the visit. The exploratory analysis focused on medication classes with 40 or more users. The primary outcome measures were medial tibiofemoral joint space width change and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) knee pain score change (12-36-month visits). Within each knee, we explored eight comparisons between users and matched or unmatched nonusers (defined two ways). An effect size of each comparison was calculated. Medication classes had potential signals if (a) both knees had less progression among users compared with nonusers, or (b) there was less progression based on structure and symptoms in one knee.

RESULTS

We screened 28 medication classes. Six medication classes had signals for fewer structural changes and better knee pain changes: alpha-adrenergic blockers, antilipemic (excluding statins and fibric acid), anticoagulants, selective serotonin reuptake inhibitors, antihistamines, and antineoplastic agents. Four medication classes had signals for structural changes alone: anti-estrogen (median effect size = 0.28; range = -0.41-0.64), angiotensin-converting enzyme inhibitors (median effect size = 0.13; range = -0.08-0.28), beta-adrenergic blockers (median effect size = 0.09; range = 0.01-0.30), and thyroid agents (median effect size = 0.04; range = -0.05-0.14). Thiazide diuretics had evidence for symptom modification (median effect size = -0.12; range = -0.24-0.04).

CONCLUSIONS

Users of neurovascular, antilipemic, or hormonal interventions may have less disease progression compared with nonusers.