Physical activity, alignment and knee osteoarthritis: data from MOST and the OAI

The mediation effects of malalignment on the relation of sex to the risk of incidence tibiofemoral osteoarthritis

OBJECTIVE

To investigate to what extent the higher risk of tibiofemoral radiographic osteoarthritis (TFROA) in females vs. males can be explained by knee malalignment.

DESIGN

Using data from Multicenter Osteoarthritis Study (MOST) and Osteoarthritis Initiative (OAI), we examined the relation of sex to the incident medial and lateral TFROA and performed mediation analyses to assess to what extent varus and valgus malalignments account for sex differences in the incident medial or lateral TFROA.

RESULTS

Of the 3462 knees without medial and lateral TFROA in MOST, the 7-year risks of medial and lateral TFROA were 16.9% and 10.0% in females, and 15.8% and 4.2% in males, respectively. Females had 2.31-fold (95% confidence interval [95% CI]: 1.73 to 3.08) higher incident lateral TFROA than males, and the relative risk (RR) of the indirect effect of sex on lateral TFROA through valgus malalignment was 1.15 (95% CI: 1.09 to 1.20), accounting for 23% of its total effect on lateral TFROA. In OAI (n = 3095 knees), females had 1.54-fold (95% CI: 1.15 to 2.04) higher incident lateral TFROA than males, and RR of the indirect effect of sex on lateral TFROA through valgus malalignment was 1.10 (95% CI: 1.04 to 1.21), accounting for 26% of its total effect on lateral TFROA. No apparent sex difference in the incident medial TFROA was found in MOST (RR = 1.05, 95% CI: 0.89 to 1.25) or OAI (RR = 1.02, 95% CI: 0.84 to 1.19).

CONCLUSION

Females had a higher risk of developing lateral TFROA than males; however, valgus malalignment only modestly explained such a difference.

Association of physical activity trajectories over 8 years and risk of knee replacement: data from the osteoarthritis initiative

BACKGROUND

To identify physical activity (PA) trajectories in adults with or at risk of knee osteoarthritis and to evaluate the association of PA trajectories with incident knee replacement (KR).

METHODS

This study used data from the Osteoarthritis Initiative. The Physical Activity Scale for the Elderly and the KR were assessed annually from baseline to 9 years. Individuals were included if they did not undergo KR surgery at baseline and had data on PA at ≥ 1 visit before KR. Latent class growth mixture Modeling was used to identify the optimal trajectories of PA before KR. Log-binomial regression models were used to assess the association between PA trajectories and the risk of KR. Data analyses were conducted in all individuals and those with radiographic osteoarthritis (ROA) and significant knee pain (Western Ontario and McMaster Osteoarthritis Index pain score of ≥ 5 on a 0-20 scale) at baseline, respectively.

RESULTS

Of 4731 participants (mean age 61.1 years, 58.5% female), four distinct and slightly declined PA trajectories were identified. Compared to individuals with a "Low" PA trajectory, those with "Medium-low", "Medium-high", or "High" PA trajectories were not significantly associated with the risk of KR (risk ratios: 0.97-1.19, all p > 0.05). Similar PA trajectories and associations with the risk of KR were observed in the subgroups of individuals with radiographic osteoarthritis and those with significant knee pain at baseline, respectively.

CONCLUSION

In participants with or at risk of knee osteoarthritis, PA slightly declines over time and may play no role in the risk of KR.

Associations between weight change, knee subcutaneous fat and cartilage thickness in overweight and obese individuals: 4-Year data from the osteoarthritis initiative

OBJECTIVE

To assess (i) the impact of changes in body weight on changes in joint-adjacent subcutaneous fat (SCF) and cartilage thickness over 4 years and (ii) the relation between changes in joint-adjacent SCF and knee cartilage thickness.

DESIGN

Individuals from the Osteoarthritis Initiative (total=399) with > 10% weight gain (n=100) and > 10% weight loss (n=100) over 4 years were compared to a matched control cohort with less than 3% change in weight (n=199). 3.0T Magnetic Resonance Imaging (MRI) of the right knee was performed at baseline and after 4 years to quantify joint-adjacent SCF and cartilage thickness. Linear regression models were used to evaluate the associations between the (i) weight change group and 4-year changes in both knee SCF and cartilage thickness, and (ii) 4-year changes in knee SCF and in cartilage thickness. Analyses were adjusted for age, sex, baseline body mass index (BMI), tibial diameter (and weight change group in analysis (ii)).

RESULTS

Individuals who lost weight over 4-years had significantly less joint-adjacent SCF (beta range, medial/lateral joint sides: 2.2-4.2 mm, p < 0.001) than controls; individuals who gained weight had significantly greater joint-adjacent SCF than controls (beta range: -1.4 to -3.9 mm, p < 0.001). No statistically significant associations were found between weight change and cartilage thickness change. However, increases in joint-adjacent SCF over 4 years were significantly associated with decreases in cartilage thickness (p = 0.04).

CONCLUSIONS

Weight change was associated with joint-adjacent SCF, but not with change in cartilage thickness. However, 4-year increases in joint-adjacent SCF were associated with decreases in cartilage thickness independent of baseline BMI and weight change group.

Subchondral Insufficiency Fractures of the Knee: A Clinical Narrative Review

» Subchondral insufficiency fractures of the knee (SIFKs) are subchondral plate fractures with a prevalence of 2% to 4% of all knee injuries.» Magnetic resonance imaging is the gold standard for evaluating SIFK, while plain radiographs have limited the use in the diagnosis of SIFK.» Among patients with SIFK, 50% to 100% have meniscal pathology.» Medical therapies and standard treatments traditionally used in the management of knee osteoarthritis differ from recommended management of SIFK patients.» Randomized controlled trials and cohort studies with long-term follow-up are needed to determine the optimal rehabilitation protocol, interventional therapy, and prognosis of SIFK patients.

Disruption of Col9a2 expression leads to defects in osteochondral homeostasis and osteoarthritis-like phenotype in mice

Background/Objective

As one of the branched chains of Type IX collagen (Col9), Collagen IX alpha2 (Col9a2) has been reported to be associated with several orthopedic conditions. However, the relationship between Col9a2 and knee osteoarthritis (KOA) remains to be elucidated.

Methods

To probe the relationship between Col9a2 and KOA, we performed a systematic analysis of Col9a2-deficient (Col9a2-/-) mice using whole-mount skeletal staining, Micro-CT (μCT), biomechanics, histomorphometry, immunohistochemistry (IHC), immunofluorescence (IF) and Elisa.

Results

We found that the subchondral bone (SCB) in the knee joint of Col9a2-/- mice became sparse and deformed in the early stage, with altered bone morphometric parameters, reduced load-bearing capacity, dysfunctional bone homeostasis (decreased osteogenesis capacity and elevated bone resorption capacity), diminished cartilage proteoglycans and disrupted cartilage extracellular matrix (ECM) anabolism and catabolism compared with the Col9a2+/+ mice. In the late stage, the cartilage degeneration in Col9a2-/- mice were particularly pronounced compared to Col9a2+/+ mice, as evidenced by severe cartilage destruction and a marked reduction in cartilage thickness and area.

Conclusion

Overall, Col9a2 is essential for maintaining osteochondral homeostasis in the knee joint of mice, and the absence of this gene is accompanied by distinct sclerosis of the SCB and a reduction in load-bearing capacity; in the late stage, in the lack of SCB stress inhibition, excessive load is consistently exerted on the cartilage, ultimately leading to osteoarthritic-like articular cartilage damage.

Levothyroxine use and longitudinal changes in thigh muscles in at-risk participants for knee osteoarthritis: preliminary analysis from Osteoarthritis Initiative cohort

BACKGROUND

We examined the association between levothyroxine use and longitudinal MRI biomarkers for thigh muscle mass and composition in at-risk participants for knee osteoarthritis (KOA) and their mediatory role in subsequent KOA incidence.

METHODS

Using the Osteoarthritis Initiative (OAI) data, we included the thighs and corresponding knees of participants at risk but without established radiographic KOA (baseline Kellgren-Lawrence grade (KL) < 2). Levothyroxine users were defined as self-reported use at all annual follow-up visits until the 4th year and were matched with levothyroxine non-users for potential confounders (KOA risk factors, comorbidities, and relevant medications covariates) using 1:2/3 propensity score (PS) matching. Using a previously developed and validated deep learning method for thigh segmentation, we assessed the association between levothyroxine use and 4-year longitudinal changes in muscle mass, including cross-sectional area (CSA) and muscle composition biomarkers including intra-MAT (within-muscle fat), contractile percentage (non-fat muscle CSA/total muscle CSA), and specific force (force per CSA). We further assessed whether levothyroxine use is associated with an 8-year risk of standard KOA radiographic (KL ≥ 2) and symptomatic incidence (incidence of radiographic KOA and pain on most of the days in the past 12 months). Finally, using a mediation analysis, we assessed whether the association between levothyroxine use and KOA incidence is mediated via muscle changes.

RESULTS

We included 1043 matched thighs/knees (266:777 levothyroxine users:non-users; average ± SD age: 61 ± 9 years, female/male: 4). Levothyroxine use was associated with decreased quadriceps CSAs (mean difference, 95%CI: - 16.06 mm²/year, - 26.70 to - 5.41) but not thigh muscles' composition (e.g., intra-MAT). Levothyroxine use was also associated with an increased 8-year risk of radiographic (hazard ratio (HR), 95%CI: 1.78, 1.15-2.75) and symptomatic KOA incidence (HR, 95%CI: 1.93, 1.19-3.13). Mediation analysis showed that a decrease in quadriceps mass (i.e., CSA) partially mediated the increased risk of KOA incidence associated with levothyroxine use.

CONCLUSIONS

Our exploratory analyses suggest that levothyroxine use may be associated with loss of quadriceps muscle mass, which may also partially mediate the increased risk of subsequent KOA incidence. Study interpretation should consider underlying thyroid function as a potential confounder or effect modifier. Therefore, future studies are warranted to investigate the underlying thyroid function biomarkers for longitudinal changes in the thigh muscles.

Quantitative CT of the knee in the IMI-APPROACH osteoarthritis cohort: Association of bone mineral density with radiographic disease severity, meniscal coverage and meniscal extrusion

OBJECTIVE

Osteoarthritis (OA) is a highly prevalent chronic condition. The subchondral bone plays an important role in onset and progression of OA making it a potential treatment target for disease-modifying therapeutic approaches. However, little is known about changes of periarticular bone mineral density (BMD) in OA and its relation to meniscal coverage and meniscal extrusion at the knee. Thus, the aim of this study was to describe periarticular BMD in the Applied Public-Private Research enabling OsteoArthritis Clinical Headway (APPROACH) cohort at the knee and to analyze the association with structural disease severity, meniscal coverage and meniscal extrusion.

DESIGN

Quantitative CT (QCT), MRI and radiographic examinations were acquired in 275 patients with knee osteoarthritis (OA). QCT was used to assess BMD at the femur and tibia, at the cortical bone plate (Cort) and at the epiphysis at three locations: subchondral (Sub), mid-epiphysis (Mid) and adjacent to the physis (Juxta). BMD was evaluated for the medial and lateral compartment separately and for subregions covered and not covered by the meniscus. Radiographs were used to determine the femorotibial angle and were evaluated according to the Kellgren and Lawrence (KL) system. Meniscal extrusion was assessed from 0 to 3.

RESULTS

Mean BMD differed significantly between each anatomic location at both the femur and tibia (p < 0.001) in patients with KL0. Tibial regions assumed to be covered with meniscus in patients with KL0 showed lower BMD at Sub (p < 0.001), equivalent BMD at Mid (p = 0.07) and higher BMD at Juxta (p < 0.001) subregions compared to regions not covered with meniscus. Knees with KL2-4 showed lower Sub (p = 0.03), Mid (p = 0.01) and Juxta (p < 0.05) BMD at the medial femur compared to KL0/1. Meniscal extrusion grade 2 and 3 was associated with greater BMD at the tibial Cort (p < 0.001, p = 0.007). Varus malalignment is associated with significant greater BMD at the medial femur and at the medial tibia at all anatomic locations.

CONCLUSION

BMD within the epiphyses of the tibia and femur decreases with increasing distance from the articular surface. Knees with structural OA (KL2-4) exhibit greater cortical BMD values at the tibia and lower BMD at the femur at the subchondral level and levels beneath compared to KL0/1. BMD at the tibial cortical bone plate is greater in patients with meniscal extrusion grade 2/3.

Is there any correlation between physical activity and severity of knee osteoarthritis in secondary referral hospital in Indonesia?

Introduction and Aim: Osteoarthritis is a pathological condition of the joints that is degenerative and progressive, affecting two-thirds of people over 65 years of age, with a prevalence of 1.39 million among males and 1.69 million in females. The main clinical manifestation of osteoarthritis is joint pain. The incidence and progression of knee osteoarthritis are strongly influenced by risk factors, consisting of systemic factors including age, sex, hormonal factors, and biomechanical factors such as obesity, physical activity, and muscle weakness. The purpose of this study was to determine if there was a relationship between physical activity, the severity of knee osteoarthritis and the level of pain based on the Kellgren-Lawrence system in gender.   Materials and Methods: This research was conducted in a cross-sectional design with 26 participants at Baptis Hospital in Batu City. As references for the interview, the GPPAQ and the WOMAC questionnaire were used. The Kellgren-Lawrence system is used to assess knee osteoarthritis.   Results: The Spearman correlation test results showed no significant relationship between physical activity and the severity of knee osteoarthritis, and no significance between physical activity and the degree of pain in general or by gender.   Conclusion: There was no statistically significant relationship between physical activity with the severity of knee osteoarthritis and the level of pain in males and females patients at Baptis Hospital in Batu City.

Heterogeneity of cartilage damage in Kellgren and Lawrence grade 2 and 3 knees: the MOST study

OBJECTIVE

Eligibility for clinical trials in osteoarthritis (OA) is usually limited to Kellgren-Lawrence (KL) grades 2 and 3 knees. Our aim was to describe the prevalence and severity of cartilage damage in KL 2 and 3 knees by compartment and articular subregion.

DESIGN

The Multicenter Osteoarthritis (MOST) study is a cohort study of individuals with or at risk for knee OA. All baseline MRIs with radiographic disease severity KL2 and 3 were included. Knee MRIs were read for cartilage damage in 14 subregions. We determined the frequencies of no, any and widespread full-thickness cartilage damage by knee compartment, and the prevalence of any cartilage damage in 14 articular subregions.

RESULTS

665 knees from 665 participants were included (mean age 63.8 ± 7.9 years, 66.5% women). 372 knees were KL2 and 293 knees were KL3. There was no cartilage damage in 78 (21.0%) medial tibio-femoral joint (TFJ), 157 (42.2%) lateral TFJ and 62 (16.7%) patello-femoral joint (PFJ) compartments of KL2 knees, and 17 (5.8%), 115 (39.3%) and 35 (12.0%) compartments, respectively, of KL3 knees. There was widespread full-thickness damage in 94 (25.3%) medial TFJ, 36 (9.7%) lateral TFJ and 176 (47.3%) PFJ compartments of KL2 knees, and 217 (74.1%), 70 (23.9%) and 104 (35.5%) compartments, respectively, of KL3 knees. The subregions most likely to have any damage were central medial femur (80.5%), medial patella (69.8%) and central medial tibia (69.9).

CONCLUSIONS

KL2 and KL3 knees vary greatly in cartilage morphology. Heterogeneity in the prevalence, severity and location of cartilage damage in in KL2 and 3 knees should be considered when planning disease modifying trials for knee OA.

DADP: Dynamic abnormality detection and progression for longitudinal knee magnetic resonance images from the Osteoarthritis Initiative

Osteoarthritis (OA) is the most common disabling joint disease. Magnetic resonance (MR) imaging has been commonly used to assess knee joint degeneration due to its distinct advantage in detecting morphologic cartilage changes. Although several statistical methods over conventional radiography have been developed to perform quantitative cartilage analyses, little work has been done capturing the development and progression of cartilage lesions (or abnormal regions) and how they naturally progress. There are two major challenges, including (i) the lack of building spatial-temporal correspondences and correlations in cartilage thickness and (ii) the spatio-temporal heterogeneity in abnormal regions. The goal of this work is to propose a dynamic abnormality detection and progression (DADP) framework for quantitative cartilage analysis, while addressing the two challenges. First, spatial correspondences are established on flattened 2D cartilage thickness maps extracted from 3D knee MR images both across time within each subject and across all subjects. Second, a dynamic functional mixed effects model (DFMEM) is proposed to quantify abnormality progression across time points and subjects, while accounting for the spatio-temporal heterogeneity. We systematically evaluate our DADP using simulations and real data from the Osteoarthritis Initiative (OAI). Our results show that DADP not only effectively detects subject-specific dynamic abnormal regions, but also provides population-level statistical disease mapping and subgroup analysis.

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.

Linking physical activity with clinical, functional, and structural outcomes: an evidence map using the Osteoarthritis Initiative

Physical activity is consistently recommended across clinical practice guidelines for managing knee osteoarthritis, yet prescription rates are low. Evidence mapping uses a systematic approach to visually illustrate and summarize published evidence, highlight gaps in the literature, and formulate research questions. The purpose of this study was to review and summarize evidence published from the Osteoarthritis Initiative (OAI) linking physical activity with clinical, functional, and structural knee osteoarthritis outcomes. Electronic databases were searched until June 2021. Studies from the OAI reporting subjective (Physical Activity Scale for the Elderly, PASE) or objective (accelerometry) physical activity data were included. Scatter plots were created to represent each outcome group (clinical, functional, structural) and physical activity measure (PASE, accelerometry) to map the evidence by the directional effect (positive, interaction, negative, or no effect) associated with physical activity. Forty-two articles were included in this review. Physical activity was quantified using PASE (n = 21), accelerometry (n = 20), or both (n = 1). Studies reported consistently positive physical activity effects on clinical (n = 22) and functional (n = 20) outcomes, with few exceptions. Structural (n = 15) outcomes were largely reported as interaction effects by physical activity intensity or sex, or as no significant effect. A network of interconnected outcomes emerged, with clinical and functional outcomes often reported together, and structural outcomes reported individually. This study provides an overview of current evidence linking physical activity to multiple interrelated knee osteoarthritis outcomes using an OAI-driven model. These evidence maps can be used as a framework to guide future investigations of the effects of physical activity on knee osteoarthritis.

Associations of Comorbid Conditions and Transitions Across States of Knee Osteoarthritis in a Community-Based Cohort

OBJECTIVE

To examine relationships between knee osteoarthritis (KOA) and obesity, diabetes mellitus (DM), and cardiovascular disease (CVD).

METHODS

Associations of time-dependent obesity, DM, and CVD with KOA transition states over approximately 18 years were examined among 4093 participants from a community-based cohort. Transition states were 1) no knee symptoms and no radiographic KOA (rKOA; Kellgren-Lawrence grade ≥2 in at least one knee), 2) asymptomatic rKOA, 3) knee symptoms only, 4) symptomatic rKOA (sxKOA; rKOA and symptoms in same knee). Markov multistate models estimated adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for associations between comorbid conditions and transitions across states, adjusting for baseline age, sex, race, education, enrollment cohort, birth year, and time-dependent knee injury history.

RESULTS

At baseline, 40% of participants had obesity, 13% had DM, and 22% had CVD (mean age = 61 years; 34% Black; 37% male). Compared with those without obesity, those with obesity had a higher hazard of worsening from no rKOA/no symptoms to asymptomatic rKOA (aHR = 1.7; 95% CI = 1.3-2.2) and from knee symptoms to sxKOA (aHR = 1.7; 95% CI = 1.3-2.3), as well as a lower hazard of symptom resolution from sxKOA to asymptomatic rKOA (aHR = 0.5 [95% = CI 0.4-0.7]). Compared with those without CVD, those with CVD had a higher hazard of worsening from no rKOA/symptoms to knee symptoms (aHR = 1.5; 95% CI = 1.1-2.1). DM was not associated with transitions of rKOA.

CONCLUSION

Prevention of obesity and CVD may limit the development or worsening of rKOA and symptoms.

The Longitudinal Relationship Between Physical Activity and Joint Space Narrowing: 48-Month Follow-Up Data from the Osteoarthritis Initiative

OBJECTIVE

To determine whether amount of physical activity (PA) is a determinant of joint space narrowing (JSN) worsening over 48-months in participants with knee osteoarthritis (OA).

METHODS

Data were obtained from the Osteoarthritis Initiative. PA, measured using the Physical Activity Scale for the Elderly (PASE), was defined as the mean value of the annual measurements conducted prior to development of worsening JSN. Worsening JSN was defined as at least a partial grade increase in OARSI JSN score over 48 months, in comparison with baseline. Restricted cubic spline (RCS) function was used to group participants based on the linear association between PA and JSN worsening. A pooled logistic regression model was used to evaluate the association between PA and JSN worsening adjusted for confounders.

RESULTS

2,167 participants were included. In total, 625 (28.8%) participants had JSN worsening over 48 months. Compared with PASE score of 140-180, PASE scores of 100-140 and >220 associated with an increased risk of JSN worsening in men with OR (95% CI) of 1.73 (1.07, 2.81) and 1.83 (1.14, 2.93) respectively. Similarly, in participants with Kellgren and Lawrence grade 2, compared with a PASE score of 140-180, PASE score of <100 and >220 were associated with increased risks of JSN worsening, with OR (95% CIs) of 1.69 (1.13, 2.54) and 1.64 (1.05, 2.56) respectively.

CONCLUSION

Compared to moderate PA, higher or lower amounts of PA are associated with elevated risk for JSN worsening in men and in participants with KL grade 2 knees.

The association between walking speed from short- and standard-distance tests with the risk of all-cause mortality among adults with radiographic knee osteoarthritis: data from three large United States cohort studies

OBJECTIVE

Adults with radiographic knee OA (rKOA) are at increased risk of mortality and walking difficulty may modify this relation. Little is known about specific aspects of walking difficulty that increase mortality risk. We investigated the association of walking speed (objective measure of walking difficulty) with mortality and examined the threshold that best discriminated this risk in adults with rKOA.

METHODS

Participants with rKOA from the Johnston County Osteoarthritis Project (JoCoOA, longitudinal population-based cohort), Osteoarthritis Initiative and Multicenter Osteoarthritis Study (OAI and MOST, cohorts of individuals with or at high risk of knee OA) were included. Baseline speed was measured via 2.4-meter (m) walk test (short-distance) in JoCoOA and 20-m walk test (standard-distance) in OAI and MOST. To examine the association of walking speed with mortality risk over 9 years, hazard ratios (HR) and 95% confidence intervals (CI) were calculated from Cox regression models adjusted for potential confounders. A Maximal Likelihood Ratio Chi-square Approach was utilized to identify an optimal threshold of walking speed predictive of mortality.

RESULTS

Deaths after 9 years of follow-up occurred in 23.3% (290/1244) of JoCoOA and 5.9% (249/4215) of OAI + MOST. Walking 0.2 m/s slower during short- and standard-distance walk tests was associated with 23% (aHR [95%CI]; 1.23 [1.10, 1.39]) and 25% (1.25 [1.09, 1.43]) higher mortality risk, respectively. Walking <0.5 m/s on short-distance and <1.2 m/s standard-distance walk tests, best discriminated those with and without mortality risk.

CONCLUSION

Slower walking speed measured via short- and standard-distance walk tests was associated with increased mortality risk in adults with rKOA.

Molecular Signaling Interactions and Transport at the Osteochondral Interface: A Review

Articular joints are comprised of different tissues, including cartilage and bone, with distinctive structural and mechanical properties. Joint homeostasis depends on mechanical and biological integrity of these components and signaling exchanges between them. Chondrocytes and osteocytes actively sense, integrate, and convert mechanical forces into biochemical signals in cartilage and bone, respectively. The osteochondral interface between the bone and cartilage allows these tissues to communicate with each other and exchange signaling and nutritional molecules, and by that ensure an integrated response to mechanical stimuli. It is currently not well known how molecules are transported between these tissues. Measuring molecular transport in vivo is highly desirable for tracking cartilage degeneration and osteoarthritis progression. Since transport of contrast agents, which are used for joint imaging, also depend on diffusion through the cartilage extracellular matrix, contrast agent enhanced imaging may provide a high resolution, non-invasive method for investigating molecular transport in the osteochondral unit. Only a few techniques have been developed to track molecular transport at the osteochondral interface, and there appear opportunities for development in this field. This review will describe current knowledge of the molecular interactions and transport in the osteochondral interface and discuss the potential of using contrast agents for investigating molecular transport and structural changes of the joint.

Risk factors for pain and functional impairment in people with knee and hip osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

To identify risk factors for pain and functional deterioration in people with knee and hip osteoarthritis (OA) to form the basis of a future 'stratification tool' for OA development or progression.

DESIGN

Systematic review and meta-analysis.

METHODS

An electronic search of the literature databases, Medline, Embase, CINAHL, and Web of Science (1990-February 2020), was conducted. Studies that identified risk factors for pain and functional deterioration to knee and hip OA were included. Where data and study heterogeneity permitted, meta-analyses presenting mean difference (MD) and ORs with corresponding 95% CIs were undertaken. Where this was not possible, a narrative analysis was undertaken. The Downs & Black tool assessed methodological quality of selected studies before data extraction. Pooled analysis outcomes were assessed and reported using the Grading of Reccomendation, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

82 studies (41 810 participants) were included. On meta-analysis: there was moderate quality evidence that knee OA pain was associated with factors including: Kellgren and Lawrence≥2 (MD: 2.04, 95% CI 1.48 to 2.81; p<0.01), increasing age (MD: 1.46, 95% CI 0.26 to 2.66; p=0.02) and whole-organ MRI scoring method (WORMS) knee effusion score ≥1 (OR: 1.35, 95% CI 0.99 to 1.83; p=0.05). On narrative analysis: knee OA pain was associated with factors including WORMS meniscal damage ≥1 (OR: 1.83). Predictors of joint pain in hip OA were large acetabular bone marrow lesions (BML; OR: 5.23), chronic widespread pain (OR: 5.02) and large hip BMLs (OR: 4.43).

CONCLUSIONS

Our study identified risk factors for clinical pain in OA by imaging measures that can assist in predicting and stratifying people with knee/hip OA. A 'stratification tool' combining verified risk factors that we have identified would allow selective stratification based on pain and structural outcomes in OA.

PROSPERO REGISTRATION NUMBER

CRD42018117643.

Total physical activity and risk of chronic low back and knee pain in middle-aged and elderly Japanese people: The Murakami cohort study

BACKGROUND

Specific components of physical activity, such as vigorous exercise and heavy occupational work, are known to increase the risk of chronic low back pain (CLBP) and chronic knee pain (CKP), but impacts of other components are less known. This study aimed to assess the relationship between total physical activity and risk of CLBP and CKP from a public health perspective.

METHODS

Participants were 7,565 individuals, aged 40-74 years, who did not have CLBP or CKP, and who participated in the 5-year follow-up survey. A self-administered questionnaire was used to obtain information on demographics, body size and lifestyle (including physical activity) in the baseline survey in 2011-2013, and on CLBP and CKP using Short Form 36 (SF-36) in the follow-up survey. Sitting, standing, walking and strenuous work for occupational activity were assessed for total physical activity, and walking slowly, walking quickly, light to moderate exercise and strenuous exercise were assessed for leisure-time physical activity using metabolic equivalent hours/day (METs score).

RESULTS

Mean age of participants was 60.1 years (SD, 8.8). Participants with higher METs scores had a significantly higher risk of CKP (p for trend = 0.0089, OR of 4th quartile = 1.29, 95% CI: 1.04-1.59 vs. 1st quartile), but not CLBP. An intermediate leisure-time METs score was associated with a lower risk of CLBP (OR = 0.75, 95%CI: 0.61-0.92 vs. 0 METs-group).

CONCLUSIONS

A high level of total physical activity may increase the risk of CKP, whereas an intermediate level of leisure-time physical activity may decrease the risk of CLBP, in middle-aged and elderly individuals.

SIGNIFICANCE

Evidence on the longitudinal association between total physical activity and CLBP and CKP in middle-aged and elderly people is lacking. We conducted a cohort study to assess this association, and found that high levels of total physical activity increased risk of CKP, and intermediate levels of leisure-time physical activity decreased risk of CLBP. This suggests that the effect of physical activity on chronic pain differed by pain site.

Association of Diabetes Mellitus and Biomarkers of Abnormal Glucose Metabolism With Incident Radiographic Knee Osteoarthritis

OBJECTIVE

The association of diabetes mellitus (DM) with increased risk of knee osteoarthritis (OA) is uncertain. We evaluated associations of DM and biomarkers of abnormal glucose metabolism with incident radiographic knee OA, controlling for body mass index (BMI).

METHODS

Participants (mean ± SD age 60.6 ± 7.8 years; mean ± SD body mass index [BMI] 29.1 ± 4.9 kg/m2 ) were from the Multicenter Osteoarthritis Study and did not have radiographic knee OA at baseline (Kellgren/Lawrence [K/L] grade <2 bilaterally). A random sample (n = 987) was selected and stratified by BMI. Baseline serum fasting glucose and homeostasis model assessment-estimated insulin resistance (HOMA-IR) were measured. Participants were categorized as having DM based on self-report, use of medication, or fasting glucose ≥126 mg/dl. Incident radiographic knee OA (K/L grade ≥2 or knee replacement) was assessed at 3 follow-up visits (30, 60, and 84 months). Knee-level pooled logistic regression analysis was performed to obtain odds ratios (ORs) (95% confidence interval [95% CI]) for associations of DM status and biomarkers of abnormal glucose metabolism with incident radiographic knee OA.

RESULTS

After adjustment for BMI, the odds of incident radiographic knee OA were not associated with baseline DM status nor with levels of fasting glucose and HOMA-IR, overall and in men. In women, HOMA-IR was inversely associated with odds of incident radiographic knee OA (adjusted OR 0.80 [95% CI 0.69-0.94], P = 0.005).

CONCLUSION

DM and higher levels of biomarkers of abnormal glucose metabolism were not associated with increased odds of incident radiographic knee OA after adjusting for BMI in this cohort overall. A possible protective association of higher HOMA-IR with incident radiographic knee OA in women warrants further investigation.

Effects of Physical Activity in Knee and Hip Osteoarthritis: A Systematic Umbrella Review

INTRODUCTION

We conducted a systematic umbrella review to evaluate the literature relating to effects of physical activity on pain, physical function, health-related quality of life, comorbid conditions and osteoarthritis (OA) structural disease progression in individuals with lower-extremity OA.

METHODS

Our primary search encompassed 2011 to February 2018 for existing systematic reviews (SR), meta-analyses (MA) and pooled analyses dealing with physical activity including exercise (not mixed with any other intervention and compared to a no-activity control group). A supplementary search encompassed 2006 to February 2018 for original research related to physical activity (including exercise) and lower limb OA progression. Study characteristics were abstracted, and risk of bias was assessed.

RESULTS

Physical activity decreased pain and improved physical function (strong evidence) and improved health-related quality of life (moderate evidence) among people with hip or knee OA relative to less active adults with OA. There was no evidence to suggest accelerated OA progression for physical activity below 10,000 steps per day. Both physical activity equivalent to the 2008 Physical Activity Guidelines for Americans (150 min·wk of moderate-intensity exercise in bouts ≥10 min) and lower levels of physical activity (at least 45 total minutes per week of moderate-intensity) were associated with improved or sustained high function. No SR/MA addressing comorbid conditions in OA were found. Measurable benefits of physical activity appeared to persist for periods of up to 6 months following cessation of a defined program.

CONCLUSIONS

People with lower-extremity OA should be encouraged to engage in achievable amounts of physical activity, of even modest intensities. They can choose to accrue minutes of physical activity throughout the entire day, irrespective of bout duration, and be confident in gaining some health and arthritis-related benefits.

[The clinical status and treatment options for osteoarthritis in patients with frailty]

Aging is an independent risk factor for the development of many diseases and geriatric syndromes. Osteoarthritis (OA), as the most common joint disease in the elderly, can be attributed to age - associated conditions. And the most significant geriatric syndrome, which dramatically affects the management and prognosis of an elderly, is frailty. The review provides current information on the prevalence of OA and frailty, their clinical and prognostic significance, and also shows the mutually aggravating role of these two conditions. The difference between non - and medication management of patients with OA and frailty is emphasized.

Physical Activity and Worsening of Radiographic Findings in Persons With or at Higher Risk of Knee Osteoarthritis

OBJECTIVE

The benefits of physical activity among persons with or at higher risk for knee osteoarthritis are well established. However, activity levels in this population are low, in part due to concern that activity will damage the knee joint. We hypothesized that sedentary and moderate-vigorous physical activity are each associated with greater risk of radiographic worsening of knee OA.

METHODS

In Osteoarthritis Initiative participants with or at higher risk for knee OA enrolled in an accelerometer substudy at 48 months (study baseline), physical activity was measured by a uniaxial accelerometer (ActiGraph GT1M). Radiographic progression was defined as any 48 month to 96 month worsening of Kellgren/Lawrence (K/L) grade scores. All analyses were knee-level; we used multivariable logistic regression with generalized estimating equations, adjusting for key covariates.

RESULTS

Of the 1,206 participants, 631 (52%) were female, the mean ± SD age was 64 ± 9 years, and mean ± SD body mass index (BMI) was 28 ± 5. The mean ± SD average daily sedentary activity was 602 ± 86 minutes, average daily light activity was 284 ± 75 minutes, and average daily moderate-vigorous activity was 20 ± 20 minutes. In 1,978 knees, 267 (14%) had worsening of K/L grade scores. In the multivariable model, age, sex, BMI, and pain, were associated with K/L grade worsening, but neither sedentary activity (adjusted odds ratio [OR] 0.99 [95% confidence interval (95% CI) 0.97-1.01]) nor moderate-vigorous activity (adjusted OR 1.00 [95% CI 0.91-1.09]) were associated with K/L grade worsening.

CONCLUSION

In persons with or at higher risk for knee OA, age, sex, BMI, and pain, but not objectively measured average daily minutes of sedentary or moderate-vigorous activity, were associated with subsequent worsening of K/L grade. Whether findings differ in persons with more severe knee OA and/or engaged more frequently in moderate-vigorous activity should be examined in future studies.

The different influence of high levels of physical activity on the incidence of knee OA in overweight and obese men and women-a gender specific analysis

OBJECTIVE

To investigate the influence of physical activity on incidence of knee osteoarthritis (OA) in overweight and obese men and women.

DESIGN

Data were extracted from the Osteoarthritis Initiative cohort on 1,667 participants without symptomatic knee OA at baseline. We used logistic regression and marginal effect models to estimate the effect of body mass index (BMI) and reported physical activity score, together with the interaction between them, on the development of radiographic knee OA, symptomatic knee OA and joint space narrowing (JSN) after 96-months.

RESULTS

Men in the most active quartile had almost double the likelihood of knee OA, independent of OA definition [e.g., odds ratio (OR) 2.4 (95%CI: 1.2-4.5) for radiographic knee OA]. Interaction analyses showed statistically significant interactions between physical activity and BMI on developing knee OA (i) radiographic OA _interaction(P = 0.039), (ii) symptomatic OA _interaction(P = 0.022), (iii) JSN _interactionP = 0.012). The margin plots in men also demonstrated that the effect of physical activity on different measures of knee OA were modified by high levels of BMI. These effects were not mirrored in women where at all BMI levels, the level of reported physical activity did not influence likelihood of knee OA independent of OA definition.

CONCLUSIONS

In overweight and obese men, there appears to be a threshold above which increasing levels of physical activity are associated with higher risk of knee OA. This is absent in women.

Risk factor heterogeneity for medial and lateral compartment knee osteoarthritis: analysis of two prospective cohorts

OBJECTIVE

To evaluate the etiologic heterogeneity between medial and lateral tibiofemoral radiographic osteoarthritis (ROA).

METHODS

Knees without medial or lateral tibiofemoral ROA at baseline were followed for 60-month in Multicenter Osteoarthritis Study (MOST) and for 48-month in Osteoarthritis Initiative (OAI). We examined the relation of previously reported risk factors to incident medial and lateral tibiofemoral ROA separately and determined the etiology heterogeneity with a ratio of rate ratios (RRs) (i.e., the RR for medial tibiofemoral ROA divided by the RR for lateral tibiofemoral ROA) using a duplication method for Cox proportional hazard regression.

RESULTS

Of 2,016 participants in MOST, 436 and 162 knees developed medial or lateral tibiofemoral ROA, respectively. Obesity and varus malalignment were 95% and 466% more strongly associated with incident medial tibiofemoral ROA than with lateral tibiofemoral ROA, respectively (ratios of RRs, 1.95 [95% confidence interval (CI):1.05-3.62] and 5.66 [95% CI:3.20-10.0]). In contrast, the associations of female sex and valgus malalignment with incident medial tibiofemoral ROA were weaker or in an opposite direction compared with lateral tibiofemoral Osteoarthritis (OA) (ratios of RRs, 0.40 [95% CI:0.26-0.63] and 0.20 [95% CI:0.12-0.34], respectively). Older age tended to show a weaker association with incident medial tibiofemoral ROA than with incident lateral tibiofemoral ROA. No heterogeneity was observed for the relation of race, knee injury, or contralateral knee ROA. These findings were closely replicated in OAI.

CONCLUSION

Risk factor profiles for medial and lateral tibiofemoral ROA are different. These results can provide a framework for the development of targeted prevention and potential treatment strategies for specific knee OA subtypes.

Objectively Measured Physical Activity and Risk of Knee Osteoarthritis

PURPOSE

This study aimed to examine the association between objectively measured physical activity and risk of developing incident knee osteoarthritis (OA) in a community-based cohort of middle-age and older adults.

METHODS

We used data from the Osteoarthritis Initiative, an ongoing prospective cohort study of adults 45 to 83 yr of age at initial enrollment with elevated risk of symptomatic knee OA. Moderate-vigorous physical activity (MVPA) was measured by a uniaxial accelerometer for seven continuous days in two data collection cycles and was categorized as inactive (<10 min·wk), low activity (10-<150 min·wk), and active (≥150 min·wk). Incident knee OA based on radiographic and symptomatic OA and joint space narrowing were analyzed as outcomes over 4 yr of follow-up. Participants free of the outcome of interest in both knees at study baseline were included (sample sizes ranged from 694 to 1331 for different outcomes). We estimated hazard ratio (HR) with 95% confidence intervals (CI).

RESULTS

In multivariate analyses, active MVPA participation was not significantly associated with risk of incident radiographic knee OA (HR = 1.52, 95% CI = 0.68-3.40), symptomatic knee OA (HR = 1.17, 95% CI = 0.44-3.09), or joint space narrowing (HR = 0.87, 95% CI = 0.37-2.06) when compared with inactive MVPA participation. Similar results were found for participants with low activity MVPA.

CONCLUSION

MVPA was not associated with the risk of developing incident knee OA or joint space narrowing over 4 yr of follow-up among Osteoarthritis Initiative participants who are at increased risk of knee OA.

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.

Acute and mid-term (six-week) effects of an ankle-foot-orthosis on biomechanical parameters, clinical outcomes and physical activity in knee osteoarthritis patients with varus malalignment

BACKGROUND

Knee osteoarthritis (KOA) is a painful disease commonly caused by high loads on the articular cartilage. Orthotic interventions aim to reduce mechanical loading, thereby alleviating pain. Traditional orthotics appear effective, but high drop-out rates have been reported over prolonged periods.

RESEARCH QUESTION

The aim of this study was to examine the effect of a novel ankle-foot orthosis (AFO) on gait parameters, physical function and activity of KOA patients.

METHODS

29 clinically diagnosed KOA patients with varus malalignment wore an AFO for 6 weeks. Prior to and after the intervention period, 3D gait analysis, physical function tests and the KOOS questionnaire were administered. Physical activity was objectively assessed with accelerometers.

RESULTS

The AFO immediately reduced the first peak of the knee adduction moment (KAM) and the KAM impulse by 41% and 19%. The knee flexion moment (KFM) was increased by 48%. After six weeks, the first KAM peak and KAM impulse were decreased by 27% and 19% while using the AFO. The KFM was increased by 71%. Furthermore, patients completed the functional tests faster (1.4-2.6%). The KOOS scores decreased significantly. No significant differences were found in physical activity parameters.

SIGNIFICANCE

The six-week AFO application significantly reduced the KAM. The patients' physical function appeared improved; yet these improvements were only minor and therefore arguably clinically irrelevant. The KFM appeared to be negatively affected after six weeks, as were the scores on the KOOS subscales. In summary, even though the AFO reduced the KAM and improved physical function, the clinical benefit for KOA patients with varus malalignment after the 6-week AFO application is debatable.

ShortFuse: Biomedical Time Series Representations in the Presence of Structured Information

In healthcare applications, temporal variables that encode movement, health status and longitudinal patient evolution are often accompanied by rich structured information such as demographics, diagnostics and medical exam data. However, current methods do not jointly optimize over structured covariates and time series in the feature extraction process. We present ShortFuse, a method that boosts the accuracy of deep learning models for time series by explicitly modeling temporal interactions and dependencies with structured covariates. ShortFuse introduces hybrid convolutional and LSTM cells that incorporate the covariates via weights that are shared across the temporal domain. ShortFuse outperforms competing models by 3% on two biomedical applications, forecasting osteoarthritis-related cartilage degeneration and predicting surgical outcomes for cerebral palsy patients, matching or exceeding the accuracy of models that use features engineered by domain experts.

Gait analysis of patients with knee osteoarthritis highlights a pathological mechanical pathway and provides a basis for therapeutic interventions

Knee osteoarthritis (OA) is a painful and incapacitating disease affecting a large portion of the elderly population, for which no cure exists. There is a critical need to enhance our understanding of OA pathogenesis, as a means to improve therapeutic options.

Knee OA is a complex disease influenced by many factors, including the loading environment. Analysing knee biomechanics during walking - the primary cyclic load-bearing activity - is therefore particularly relevant.

There is evidence of meaningful differences in the knee adduction moment, flexion moment and flexion angle during walking between non-OA individuals and patients with medial knee OA. Furthermore, these kinetic and kinematic gait variables have been associated with OA progression.

Gait analysis provides the critical information needed to understand the role of ambulatory biomechanics in OA development, and to design therapeutic interventions. Multidisciplinary research is necessary to relate the biomechanical alterations to the structural and biological components of OA.

Cite this article: Favre J, Jolles BM. Analysis of gait, knee biomechanics and the physiopathology of knee osteoarthritis in the development of therapeutic interventions. EFORT Open Rev 2016;1:368-374. DOI: 10.1302/2058-5241.1.000051.

Longitudinal Course of Physical Function in People With Symptomatic Knee Osteoarthritis: Data From the Multicenter Osteoarthritis Study and the Osteoarthritis Initiative

OBJECTIVE

Pain and functional decline are hallmarks of knee osteoarthritis (OA). Nevertheless, longitudinal studies unexpectedly reveal stable or improved physical function. The aim of this study was to impute missing and pre-total knee replacement (TKR) values to describe physical function over time among people with symptomatic knee OA.

METHODS

We included participants from the Multicenter Osteoarthritis Study (MOST) and the Osteoarthritis Initiative (OAI) with incident symptomatic knee OA, observed during the first 30 months in MOST and 36 months in OAI. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function (WOMAC-PF), the 5-times sit-to-stand test, and the 20-meter-walk test were assessed at 4 and 5 years in MOST and at 6 years in OAI. We used a multiple imputation method for missing visits, and estimated pre-TKR values close to the time of TKR, using a fitted local regression smoothing curve. In mixed-effect models, we investigated the physical function change over time, using data before and after imputation and calculation of pre-TKR values.

RESULTS

In MOST, 225 (8%) had incident knee OA, with corresponding 577 (12.7%) in OAI. After adjusting for pre-TKR values and imputing missing values, we found that WOMAC-PF values remained stable or slightly declined over time, and the 20-meter-walk test results changed from stable in nonimputed analyses to worsening using imputed data.

CONCLUSION

Data from MOST and OAI showed stable to worsening physical function over time in people with incident symptomatic knee OA after imputing missing values and adjusting pre-TKR values.

Determinants of knee replacement in subjects with a history of arthroscopy: data from the osteoarthritis initiative

OBJECTIVE

To investigate the risk and determinants of knee replacement (KR) in subjects with or at risk of osteoarthritis (OA) and a history of arthroscopy.

METHODS

Data from the osteoarthritis initiative cohort were analyzed (n = 4796, up to the seventh year of follow-up). Cox proportional hazard analysis was used to determine the risk of KR according to the history of arthroscopy. A multivariable model was used to determine the risk factors for KR among subjects with a history of arthroscopy (n = 842), including age, gender, body mass index, history of knee injury, and baseline physical activity scale for the elderly, Western Ontario and McMaster (WOMAC) total score, and radiographic Kellgren and Lawrence (KL) score.

RESULTS

History of arthroscopy was associated with risk of KR after adjustments for the mentioned determinants of OA (HR: 1.90 (1.49-2.44); P value <0.001). Female gender (HR: 1.86 (1.30-2.68); P value <0.001), higher WOMAC (HR: 1.02 (1.01-1.03); P value <0.001), and KL score (HR: 2.64 (2.08-3.35); P value <0.001) increased the risk of KR among subjects with a history of arthroscopy. Subjects with a history of knee injury had 50 % lower risk of KR (HR: 0.50 (0.35-0.72); P value <0.001) after arthroscopy.

CONCLUSION

Female gender, more clinical symptoms and radiographic signs of OA, was associated with higher risk of future KR in subjects with a history of arthroscopy. Subjects with arthroscopy in the setting of concomitant knee injury were 50 % less likely to undergo KR compared to subjects who underwent arthroscopy without a history of concomitant knee injury.

Association of Physical Activity Measured by Accelerometer, Knee Joint Abnormalities, and Cartilage T2 Measurements Obtained From 3T Magnetic Resonance Imaging: Data From the Osteoarthritis Initiative

OBJECTIVE

To study the cross-sectional association between physical activity measured with an accelerometer, structural knee abnormalities, and cartilage T2 values assessed with 3T magnetic resonance imaging (MRI).

METHODS

We included 274 subjects from the Osteoarthritis Initiative cohort without definite radiographic osteoarthritis (Kellgren/Lawrence grades 0 and 1) and with at most mild pain, stiffness, and functional limitation in the study knee (Western Ontario and McMaster Universities Osteoarthritis Index scale 0-1), which had not limited their activity due to knee pain. Physical activity was measured over 7 days with an ActiGraph GT1M accelerometer. Subjects were categorized by quartile of physical activity based on the average daily minutes of moderate to vigorous physical activity (mv-PA). MRI images of the right knee (at 48-month visit) were assessed for structural abnormalities using a modified Whole-Organ Magnetic Resonance Imaging Score (WORMS) and for T2 relaxation times derived from segmented cartilage of 4 femorotibial regions and the patella. WORMS grades and T2 measurements were compared between activity quartiles using a linear regression model. Covariates included age, sex, body mass index, knee injury, family history of knee replacement, knee symptoms, hip and ankle pain, and daily wear time of the accelerometer.

RESULTS

Higher mv-PA was associated with increased severity (P = 0.0087) and number of lesions of the medial meniscus (P = 0.0089) and with severity of bone marrow edema lesions (P = 0.0053). No association between cartilage lesions and mv-PA was found. T2 values of cartilage (loss, damage, and abnormalities) tended to be greater in the higher quartiles of mv-PA, but the differences were nonsignificant.

CONCLUSION

In knees without radiographic osteoarthritis in subjects with no or mild knee pain, higher physical activity levels were associated with increases in meniscal and bone marrow edema pattern lesions.

Predictive value of semi-quantitative MRI-based scoring systems for future knee replacement: data from the osteoarthritis initiative

PURPOSE

To evaluate, in a confirmatory fashion, whether baseline and change from baseline to 24-month follow-up in cartilage damage, bone marrow lesions and meniscal damage are predictors of knee replacement (KR) in subjects with a high risk of osteoarthritis (OA), independent of the level of physical activity, symptom severity and radiographic abnormalities.

METHODS

Data from the Osteoarthritis Initiative's (OAI) baseline and 24-month follow-up knee MRIs of 115 patients (age range: 45-78 years; 48 % female; BMI: 20.9-48.7) were analyzed. Cartilage, bone marrow and menisci were semi-quantitatively scored according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS) and Boston-Leeds Osteoarthritis Knee Score (BLOKS) systems in all compartments. Baseline and 24-month interval changes in structural tissue damage assessed by BLOKS and WORMS were used as predictors of KR independent of clinical and radiographic parameters using Cox hazard analysis. Adjustments were performed for age, gender, BMI and physical activity (Physical Activity Scale for the Elderly: PASE), Western Ontario and McMaster Questionnaire (WOMAC) total score and radiographic Kellgren-Lawrence (KL) score.

RESULTS

BLOKS and WORMS baseline cartilage scores were predictors of KR independent of the PASE, WOMAC and KL score. One score increase in the average baseline BLOKS full-thickness cartilage defect score was associated with a [hazard ratio (95 % CI)] 13.55 (3.61-50.89) times greater risk of KR independent of the PASE, WOMAC and KL score. Net reclassification improvements (NRIs) of the additional evaluation of 24-month follow-up MRI scores and assessment of changes were not significant for prediction of KR (NRI range: - 7.23 - 24.8 %).

CONCLUSIONS

The BLOKS cartilage score for full-thickness cartilage defects had the highest hazard for KR. Follow-up MRI changes in structural tissue damage, detected by BLOKS and WORMS cartilage, bone marrow or meniscus scores (up to 24 months) had no significant predictive value in addition to the baseline MRI.

[Osteotomy around the knee vs. unicondylar knee replacement]

BACKGROUND

Osteotomy around the knee and unicondylar knee replacement can both produce excellent results in unilateral knee osteoarthritis. The indications for these procedures differ significantly and are discussed in this article.

METHODS

A weight-bearing long-leg radiograph, clinical stability tests and varus-valgus-stress radiographs are mandatory for a preoperative analysis. Osteotomy is a safe and reproducible procedure when a biplanar cutting technique is used and fixation is achieved with a plate fixator. Unicondylar knee replacement can be performed minimally invasive with a quadriceps-sparing arthrotomy.

EVALUATION

High tibial osteotomy and unicondylar knee may produce good results in unilateral osteoarthritis of the knee. Our multicenter follow-up study with 533 patients revealed good functional outcome scores with a low complication rate. The subjective ratings were better than in comparable groups with unicondylar knee replacement and with total knee arthroplasty.

CONCLUSIONS

The main criterium for osteotomy versus unicondylar knee replacement is constitutional deformity of femur or tibia. In constitutional deformity, osteotomy has a very good prognosis. The results are not dependent on age, BMI, or grade of osteoarthritis. Activity and ligament stability of the knee are secondary criteria in favor of osteotomy. Medial osteoarthritis without constitutional deformity should be treated with unicondylar knee replacement.

The effects of oxygen level and glucose concentration on the metabolism of porcine TMJ disc cells

OBJECTIVE

To determine the combined effect of oxygen level and glucose concentration on cell viability, ATP production, and matrix synthesis of temporomandibular joint (TMJ) disc cells.

DESIGN

TMJ disc cells were isolated from pigs aged 6-8 months and cultured in a monolayer. Cell cultures were preconditioned for 48 h with 0, 1.5, 5, or 25 mM glucose DMEM under 1%, 5%, 10%, or 21% O2 level, respectively. The cell viability was measured using the WST-1 assay. ATP production was determined using the Luciferin-Luciferase assay. Collagen and proteoglycan synthesis were determined by measuring the incorporation of [2, 3-(3)H] proline and [(35)S] sulfate into the cells, respectively.

RESULTS

TMJ disc cell viability significantly decreased (P < 0.0001) without glucose. With glucose present, decreased oxygen levels significantly increased viability (P < 0.0001), while a decrease in glucose concentration significantly decreased viability (P < 0.0001). With glucose present, decreasing oxygen levels significantly reduced ATP production (P < 0.0001) and matrix synthesis (P < 0.0001). A decreased glucose concentration significantly decreased collagen synthesis (P < 0.0001). The interaction between glucose and oxygen was significant in regards to cell viability (P < 0.0001), ATP production (P = 0.00015), and collagen (P = 0.0002) and proteoglycan synthesis (P < 0.0001).

CONCLUSIONS

Although both glucose and oxygen are important, glucose is the limiting nutrient for TMJ disc cell survival. At low oxygen levels, the production of ATP, collagen, and proteoglycan are severely inhibited. These results suggest that steeper nutrient gradients may exist in the TMJ disc and it may be vulnerable to pathological events that impede nutrient supply.

Diseased Region Detection of Longitudinal Knee Magnetic Resonance Imaging Data

Magnetic resonance imaging (MRI) has become an important imaging technique for quantifying the spatial location and magnitude/direction of longitudinal cartilage morphology changes in patients with osteoarthritis (OA). Although several analytical methods, such as subregion-based analysis, have been developed to refine and improve quantitative cartilage analyses, they can be suboptimal due to two major issues: the lack of spatial correspondence across subjects and time and the spatial heterogeneity of cartilage progression across subjects. The aim of this paper is to present a statistical method for longitudinal cartilage quantification in OA patients, while addressing these two issues. The 3D knee image data is preprocessed to establish spatial correspondence across subjects and/or time. Then, a Gaussian hidden Markov model (GHMM) is proposed to deal with the spatial heterogeneity of cartilage progression across both time and OA subjects. To estimate unknown parameters in GHMM, we employ a pseudo-likelihood function and optimize it by using an expectation-maximization (EM) algorithm. The proposed model can effectively detect diseased regions in each OA subject and present a localized analysis of longitudinal cartilage thickness within each latent subpopulation. Our GHMM integrates the strengths of two standard statistical methods including the local subregion-based analysis and the ordered value approach. We use simulation studies and the Pfizer longitudinal knee MRI dataset to evaluate the finite sample performance of GHMM in the quantification of longitudinal cartilage morphology changes. Our results indicate that GHMM significantly outperforms several standard analytical methods.

CT imaging for evaluation of calcium crystal deposition in the knee: initial experience from the Multicenter Osteoarthritis (MOST) study

OBJECTIVE

Role of intra-articular calcium crystals in osteoarthritis (OA) is unclear. Imaging modalities used to date for its evaluation have limitations in their ability to fully characterize intra-articular crystal deposition. Since Computed Tomography (CT) imaging provides excellent visualization of bones and calcified tissue, in this pilot project we evaluated the utility of CT scan in describing intra-articular calcium crystal deposition in the knees.

METHOD

We included 12 subjects with and four subjects without radiographic chondrocalcinosis in the most recent visit from the Multicenter Osteoarthritis (MOST) study, which is a longitudinal cohort of community-dwelling older adults with or at risk for knee OA. All subjects underwent CT scans of bilateral knees. Each knee was divided into 25 subregions and each subregion was read for presence of calcium crystals by a musculoskeletal radiologist. To assess reliability, readings were repeated 4 weeks later.

RESULTS

CT images permitted visualization of 25 subregions with calcification within and around the tibio-femoral and patello-femoral joints in all 24 knees with radiographic chondrocalcinosis. Intra-articular calcification was seen universally including meniscal cartilage (most common site involved in 21/24 knees), hyaline cartilage, cruciate ligaments, medial collateral ligament and joint capsule. Readings showed good agreement for specific tissues involved with calcium deposition (kappa: 0.70, 95% CI 0.62-0.80).

CONCLUSION

We found CT scan to be a useful and reliable tool for describing calcium crystal deposition in the knee and therefore potentially for studying role of calcium crystals in OA. We also confirmed that "chondrocalcinosis" is a misnomer because calcification is present ubiquitously.

The influence of long-term exposure and timing of physical activity on new joint pain and stiffness in mid-age women

OBJECTIVE

To examine the influence of long-term exposure and timing of physical activity (PA) on new joint pain/stiffness in mid-age women.

METHODS

Data were from 5105 participants (born 1946-51) in the Australian Longitudinal Study on Women's Health (ALSWH) who completed survey items on PA (1998, 2001 and 2004) and joint pain/stiffness (2007 and 2010). PA was categorized in five levels at each survey and summed into a cumulative PA score (CPA, range 0-12). Associations were analysed using logistic regression, with separate models for the cumulative model (using CPA), the sensitive periods model (i.e., PA measured at each survey in one regression model) and the critical periods model (i.e., separate regression models for PA at each survey).

RESULTS

951 (18.6%) participants reported new-onset joint pain/stiffness. In the cumulative model, CPA was associated joint pain/stiffness when included as a continuous variable (adjusted odds ratio [OR] = 0.97, 95% confidence interval [CI] = 0.95-0.99), but not when included as a categorical variable. In both the sensitive periods and critical periods models, low to high levels of PA in 2001 and 2004 had stronger inverse associations with joint pain/stiffness than PA levels in 1998. The model fit was better for the sensitive periods than the cumulative or critical periods models.

CONCLUSIONS

In mid-age women, PA between the ages 47 and 58 was associated with a lower risk of joint pain/stiffness 9 years later. Associations were stronger for PA in the last 6 years than for earlier PA.

Knee osteoarthritis and frailty: findings from the Multicenter Osteoarthritis Study and Osteoarthritis Initiative

BACKGROUND

Knee osteoarthritis (OA) and frailty are two conditions that are associated with functional limitation and disability in elders, yet their relation to one another is not known.

METHODS

We included participants from two large, multicenter studies enriched with community dwelling older adults with knee OA (Multicenter Osteoarthritis Study and Osteoarthritis Initiative). Knee OA was defined radiographically (ROA) and symptomatically (SOA). Frailty was defined using the Study of Osteoporotic Fracture index as the presence of ≥2 of the following: (i) weight loss >5% between two consecutive visits; (ii) inability to arise from chair five times without support; (iii) poor energy. Cross-sectional and longitudinal associations of knee OA with prevalent and incident frailty, respectively, were examined using binomial regression with robust variance estimation, adjusting for potential confounders.

RESULTS

In the cross-sectional analyses, frailty was more prevalent among participants with ROA (4.39% vs 2.77%; PR 1.60 [1.07, 2.39]) and SOA (5.88% vs 2.79%; PR 1.92 [1. 35, 2.74]) compared with those without ROA or SOA, respectively. In the longitudinal analyses, risk of developing frailty was greater among those with ROA (4.73% vs 2.50%; RR 1.45 [0.91, 2.30]) and SOA (6.30% vs 2.83%; RR 1.66 [1.11, 2.48]) than those without ROA or SOA, respectively.

CONCLUSIONS

Knee OA is associated with greater prevalence and risk of developing frailty. Understanding the mechanisms linking these two common conditions of older adults would aid in identifying novel targets for treatment or prevention of frailty.

Imaging research results from the osteoarthritis initiative (OAI): a review and lessons learned 10 years after start of enrolment

The Osteoarthritis Initiative (OAI) is a multicentre, prospective, observational, cohort study of knee osteoarthritis (OA) that began recruitment in 2004. The OAI provides public access to clinical and image data, enabling researchers to examine risk factors/predictors and the natural history of knee OA incidence and progression, and the qualification of imaging and other biomarkers. In this narrative review, we report imaging findings and lessons learned 10 years after enrolment has started. A literature search for full text articles published from the OAI was performed up to 31 December 2013 using Pubmed and the OAI web page. We summarise the rationale, design and imaging protocol of the OAI, and the history of OAI publications. We review studies from early partial, and later full OAI public data releases. The latter are structured by imaging method and tissue, reviewing radiography and then MRI findings on cartilage morphology, cartilage lesions and composition (T2), bone, meniscus, muscle and adipose tissue. Finally, analyses directly comparing findings from MRI and radiography are summarised. Ten years after the first participants were enrolled and first papers published, the OAI has become an invaluable resource to the OA research community. It has fuelled novel methodological approaches of analysing images, and has provided a wealth of information on OA pathophysiology. Continued collection and public release of long-term observations will help imaging measures to gain scientific and regulatory acceptance as 'prognostic' or 'efficacy of intervention' biomarkers, potentially enabling shorter and more efficient clinical trials that can test structure-modifying therapeutic interventions (NCT00080171).

Fit and Strong! Plus: design of a comparative effectiveness evaluation of a weight management program for older adults with osteoarthritis

Osteoarthritis (OA) is the most common chronic condition and principal cause of disability among older adults. The current obesity epidemic has contributed to this high prevalence rate. Fortunately both OA symptoms and obesity can be ameliorated through lifestyle modifications. Physical activity (PA) combined with weight management improves physical function among obese persons with knee OA but evidence-based interventions that combine PA and weight management are limited for this population. This paper describes a comparative effectiveness trial testing an evidence-based PA program for adults with lower extremity (LE) OA, Fit and Strong!, against an enhanced version that also addresses weight management based on the evidence-based Obesity Reduction Black Intervention Trial (ORBIT). Adult participants (n=400) with LE OA, age 60+, overweight/obese, and not meeting PA requirements of ≥ 150 min per week, are randomized to one of the two programs. Both 8-week interventions meet 3 times per week and include 60 min of strength, flexibility, and aerobic exercise instruction followed by 30 min of education/group discussion. The Fit and Strong! education sessions focus on using PA to manage OA; whereas Fit and Strong! Plus addresses PA and weight loss management strategies. Maintenance of behavior change is reinforced in both groups during months 3-24 through telephone calls and mailed newsletters. Outcomes are assessed at baseline, and 2, 6, 12, 18, and 24 months. Primary outcomes are dietary change at 2 months followed by weight loss at 6 months that is maintained at 24 months. Secondary outcomes assess PA, physical performance, and anxiety/depression.