The role of atherosclerosis in osteoarthritis

Fundamentals of osteoarthritis. Rehabilitation: Exercise, diet, biomechanics, and physical therapist-delivered interventions

Insights related to the pathogenesis of osteoarthritis (OA) have informed rehabilitative treatments that aim to mitigate the influence of several known impairments and risk factors for OA, with the goal to improve pain, function, and quality of life. The purpose of this invited narrative review is to provide fundamental knowledge to non-specialists about exercise and education, diet, biomechanical interventions, and other physical therapist-delivered treatments. In addition to summarizing the rationale for common rehabilitative therapies, we provide a synthesis of current core recommendations. Robust evidence based on randomized clinical trials supports exercise with education and diet as core treatments for OA. Structured, supervised exercise therapy is advised. The mode of exercise may vary but should be individualized. The dose should be based on an initial assessment, the desired physiological changes, and progressed when appropriate. Diet combined with exercise is strongly recommended and studies demonstrate a dose-response relationship between the magnitude of weight loss and symptom improvement. Recent evidence suggests the use of technology to remotely deliver exercise, diet and education interventions is cost-effective. Although several studies support the mechanisms for biomechanical interventions (e.g., bracing, shoe inserts) and physical therapist-delivered (passive) treatments (e.g., manual therapy, electrotherapeutic modalities) fewer rigorous randomized trials support their clinical use; these therapies are sometimes recommended as adjuncts to core treatments. The mechanisms of action for all rehabilitative interventions include contextual factors such as attention and placebo effects. These effects can challenge our interpretation of treatment efficacy from clinical trials, yet also provide opportunities to maximize patient outcomes in clinical practice. When evaluating rehabilitative interventions, the field may benefit from increased emphasis on research that considers contextual factors while evaluating mechanistic, longer-term, clinically-important and policy-relevant outcome measures.

Characteristics of Preoperative Arteriosclerosis Evaluated by Cardio-Ankle Vascular Index in Patients with Osteoarthritis before Total Knee Arthroplasty

PURPOSE

Cardiovascular disease (CVD) is a major risk factor for mortality in patients with osteoarthritis, and comorbidities increase postoperative complications after total knee arthroplasty (TKA). Arteriosclerosis plays a main role in hemodynamic dysfunction and CVD; however, arteriosclerosis has not been preoperatively evaluated before TKA using the cardio-ankle vascular index (CAVI). In this study, we evaluated the degree of preoperative arteriosclerosis using the CAVI in patients undergoing TKA, as well as its correlations with several preoperative patient factors.

METHODS

Arteriosclerosis was evaluated in 209 consecutive patients (251 knees) with osteoarthritis who underwent TKA at our institution between May 2011 and June 2022. The CAVI was measured in the supine position 1 day before TKA, and the correlations between the CAVI and several clinical factors were analyzed.

RESULTS

The CAVI was normal in 62 knees (25%), borderline in 71 knees (28%), and abnormal in 118 knees (47%). Univariate analysis revealed a moderate positive correlation between preoperative CAVI and age (r = 0.451, p < 0.001) and a weak negative correlation between preoperative CAVI and body weight (r = -0.306, p < 0.001) and body mass index (BMI) (r = -0.319, p < 0.001). Multivariate analysis showed that age (β = 0.349, p < 0.001) and BMI (β = -0.235, p < 0.001) were significantly correlated with preoperative CAVI.

CONCLUSION

Arteriosclerosis should be carefully managed intraoperatively and postoperatively in patients with osteoarthritis undergoing TKA, particularly in older patients and patients with a low BMI.

Unsupervised machine-learning algorithms for the identification of clinical phenotypes in the osteoarthritis initiative database

OBJECTIVES

Osteoarthritis (OA) is a complex disease comprising diverse underlying patho-mechanisms. To enable the development of effective therapies, segmentation of the heterogenous patient population is critical. This study aimed at identifying such patient clusters using two different machine learning algorithms.

METHODS

Using the progression and incident cohorts of the Osteoarthritis Initiative (OAI) dataset, deep embedded clustering (DEC) and multiple factor analysis with clustering (MFAC) approaches, including 157 input-variables at baseline, were employed to differentiate specific patient profiles.

RESULTS

DEC resulted in 5 and MFAC in 3 distinct patient phenotypes. Both identified a "comorbid" cluster with higher body mass index (BMI), relevant burden of comorbidity and low levels of physical activity. Both methods also identified a younger and physically more active cluster and an elderly cluster with functional limitations, but low disease impact. The additional two clusters identified with DEC were subgroups of the young/physically active and the elderly/physically inactive clusters. Overall pain trajectories over 9 years were stable, only the numeric rating scale (NRS) for pain showed distinct increase, while physical activity decreased in all clusters. Clusters showed different (though non-significant) trajectories of joint space changes over the follow-up period of 8 years.

CONCLUSION

Two different clustering approaches yielded similar patient allocations primarily separating complex "comorbid" patients from healthier subjects, the latter divided in young/physically active vs elderly/physically inactive subjects. The observed association to clinical (pain/physical activity) and structural progression could be helpful for early trial design as strategy to enrich for patients who may specifically benefit from disease-modifying treatments.

Prevention of Osteoarthritis Progression by Statins, Targeting Metabolic and Inflammatory Aspects: A Review

Background and purpose:

Several traditional risk factors of atherosclerosis such as age, obesity, and altered lipid metabolism are shared with osteoarthritis (OA). Metabolic abnormalities and atheromatous vascular disease are linked with systemic inflammation and progression of OA. Hence, treatment of OA with statins is expected to improve metabolic abnormalities and prevent OA progression. Many studies which have addressed this issue found inconsistent results. This review aims to elucidate the effect of statins in OA by summarizing the existing data.

Methods:

Potential studies in English language published in Medline/PubMed, Scopus and Google Scholar since 2000 were searched by using keywords such as osteoarthritis, statins, progression, treatment, prevalence, synovitis, pain. Fourteen papers were found to be relevant and were summarised.

Results:

Data regarding symptomatic effect of statins in OA are scarce and the results varied from no effect to a small improvement or even increased risk of pain in knee OA. However, most studies on the incidence and progression of OA found a significant decreased risk of incident OA, as well as reduced risk of radiographic progression in statin users vs. non-users. Factors such as patient adherence, duration of treatment, and higher cumulative statin doses were associated with greater efficacy.

Conclusion:

Existing data indicate a preventing effect of statin therapy on OA progression. However, unless a formal meta-analysis with weight analysis is made, a conclusion cannot be drawn.

Dual Role of SIRT1 in Autophagy and Lipid Metabolism Regulation in Osteoarthritic Chondrocytes

Background and Objectives: Osteoarthritis (OA) is one of the most common and highly prevalent types of arthritis, also considered a multiphenotypic disease with a strong metabolic component. Ageing is the primary risk factor for OA, while the age-related decline in autophagic activity affects cell function and chondrocyte homeostasis. The aim of this study was to investigate the role of sirtuin 1 (SIRT1) in autophagy dysregulation and lipid metabolism in human OA chondrocytes. Materials and Methods: OA chondrocytes were treated with Resveratrol, Hydroxycloroquine (HCQ) or 3-Methyladenine (3-MA) and HCQ or 3-MA followed by siRNA against SIRT1 (siSIRT1). Then, SIRT1, AcNF-κBp65, LOX-1 and autophagy-related proteins ATG5, ATG13, PI3K class III, Beclin-1, LC3 and ULK protein levels were evaluated using Western blot. Normal articular chondrocytes were treated under serum starvation and/or siSIRT1, and the protein expression levels of the above autophagy-related proteins were evaluated. The staining patterns of LC3/p62 and LOX-1 were analyzed microscopically by immunofluorescence. SIRT1/LC3 complex formation was analyzed by immunoprecipitation. Results: SIRT1 and LOX-1 protein expression were negatively correlated in OA chondrocytes. SIRT1 regulated LOX-1 expression via NF-κΒ deacetylation, while treatment with Resveratrol enhanced SIRT1 enzymatic activity, resulting in LOX-1 downregulation and autophagy induction. In OA chondrocytes, SIRT1 was recognized as an autophagy substrate, formed a complex with LC3 and was consequently subjected to cytoplasmic autophagosome-lysosome degradation. Moreover, siSIRT1-treated normal chondrocytes showed decreased autophagic activity, while double-treated (siSIRT1 and serum starvation) cells showed no induction of autophagy. Conclusions: Our results suggest that SIRT1 regulates lipid homeostasis through LOX-1 expression regulation. Additionally, we indicate that the necessity of SIRT1 for autophagy induction in normal chondrocytes, together with its selective autophagic degradation in OA chondrocytes, could contribute to autophagy dysregulation in OA. We, therefore, suggest a novel regulatory scheme that functionally connects lipid metabolism and autophagy in late-stage OA.

Preventative and Disease-Modifying Investigations for Osteoarthritis Management Are Significantly Under-represented in the Clinical Trial Pipeline: A 2020 Review

PURPOSE

To conduct a review of active United States-based clinical trials investigating preventative, symptom resolution, and disease-modifying therapies for osteoarthritis (OA).

METHODS

We conducted a review of currently active clinical trials for OA using data obtained from the ClinicalTrials.gov database as of August 2020. The inclusion criteria were active studies registered in the United States that involved the prevention, symptom resolution, or disease modification of OA. Descriptive statistics were recorded and summarized.

RESULTS

A total of 3,859 clinical trials were identified, and 310 were included in the final analysis. Of the currently active trials, 89% (n = 275) targeted symptom resolution in patients with existing OA, 6% (n = 19) targeted OA disease-modifying therapeutics, and 5% (n = 16) targeted the prevention of OA in high-risk patients (P < .001). Primary interventions included medical devices (44%, n = 137), pharmaceutical drugs (14%, n = 42), surgical procedures (14%, n = 42), cellular biologics (13%, n = 41), and behavioral therapies (13%, n = 41). There was a significantly higher number of disease-modifying therapeutics for cellular biologics than pharmaceutical drugs (30% vs 14%) (P = .015). Most trials targeted the knee joint (63%, P = .042), with 38% of all trials evaluating joint arthroplasty. There were no significant differences between private sector and government funding sources (43% and 49%, respectively) (P = .288), yet there was a significantly lower rate of funding from industry (8%) (P = .026).

CONCLUSIONS

There was a significantly higher number of clinical trials investigating symptomatic resolution therapy (89%) for existing OA in comparison to preventative (5%) and disease-modifying (6%) therapies. The most common interventions involved medical devices and joint replacement surgery, with the knee joint accounting for more than 60% of the current clinical trials for OA. There was a significantly higher number of disease-modifying therapeutics for cellular biologics than pharmaceutical drugs. Funding of clinical trials was split between the private sector and government, with a low rate of reported funding from industry partners.

CLINICAL RELEVANCE

Identifying existing needs in the current market may help increase rates of research funding or optimize current funding pathways, in this study, specifically for targeting unaddressed focus areas in OA research. Our systematic review highlights the potential need for additional research and development regarding OA preventative and disease-modifying therapies.

Mediation of the association between obesity and osteoarthritis by blood pressure, vessel wall stiffness and subclinical atherosclerosis

Objective

We investigated the role of blood pressure, vessel wall stiffness [pulse wave velocity (PWV)] and subclinical atherosclerosis markers [carotid intima-media thickness (cIMT), popliteal vessel wall thickness (pVWT)] as mediators of the association of obesity with OA.

Methods

We used cross-sectional data from a subset of the population-based NEO study (n = 6334). We classified clinical hand and knee OA by the ACR criteria, and structural knee OA, effusion and bone marrow lesions on MRI (n = 1285). cIMT was assessed with ultrasonography. pVWT was estimated on knee MRI (n = 1285), and PWV by abdominal velocity-encoded MRIs (n = 2580), in subpopulations. Associations between BMI and OA were assessed with logistic regression analyses, adjusted for age, sex and education. Blood pressure, cIMT, pVWT and PWV were added to the model to estimate mediation.

Results

The population consisted of 55% women, with a mean (s.d.) age of 56(6) years. Clinical hand OA was present in 8%, clinical knee OA in 10%, and structural knee OA in 12% of participants. BMI was positively associated with all OA outcomes. cIMT partially mediated the association of BMI with clinical hand OA [10.6 (6.2; 30.5)%], structural knee OA [3.1 (1.9; 7.3)%] and effusion [10.8 (6.0; 37.6)%]. Diastolic blood pressure [2.1 (1.6; 3.0)%] minimally mediated the association between BMI and clinical knee OA. PWV and pVWT did not mediate the association between BMI and OA.

Conclusions

cIMT and diastolic blood pressure minimally mediated the association of BMI with OA. This suggests that such mediation is trivial in the middle-aged population.

Pain Pharmacotherapy in a Large Cohort of Patients with Osteoarthritis: A Real-World Data Analysis

INTRODUCTION

There is limited evidence on the consumption of analgesics in real-world large cohorts of patients with osteoarthritis (OA), especially in those with comorbidities. We aimed to characterize the use of pharmacological analgesic treatments, evaluate standardized comorbidity rates, and assess treatment trends. Our hypotheses were: (1) OA patients generally consume low and inconsistent pharmacological analgesic treatments; (2) analgesic treatment is often non-congruent with comorbidity-related safety concerns.

METHODS

The study was carried out at the second largest health maintenance organization in Israel. Members aged 18 years or above who were diagnosed with OA before December 31, 2018, were included. Information was obtained from the members' electronic medical record (EMR) including data on dispensed prescriptions, which were used to estimate analgesic consumption.

RESULTS

A total of 180,126 OA patients were included in our analyses; analgesics were dispensed to 64.2% of the patients, with oral NSAIDs and opioids dispensed to 34.1 and 22.9% of the OA population, respectively. Analgesic use increased with time lapsed from OA diagnosis (p < 0.001), up to a median of 59 days covered (IQR, 20-175) after 21 years. Rates of most comorbidities in the OA population were higher compared to the MHS general population. Patients with comorbidities used more NSAIDs and opioids compared to those without them.

CONCLUSIONS

Most OA patients use analgesics, usually oral NSAIDs. Analgesic use remains relatively low throughout the years, indicating that many OA patients are not being treated pharmacologically for pain on a regular basis. Despite having higher rates of several comorbidities compared to MHS general population, many OA patients are still treated with analgesics that can be associated with a worsening in comorbidity.

Correlation of atherosclerosis and osteoarthritis in ancient Egypt: A standardized evaluation of 45 whole-body CT examinations

OBJECTIVE

To correlate atherosclerosis (Ath) and osteoarthritis (OA) in mummies from ancient Egypt.

MATERIALS

Whole-body CT examinations of 23 mummies from the Ägyptisches Museum und Papyrussammlung, Berlin, Germany, and 22 mummies from the Museo Egizio, Turin, Italy.

METHODS

Ath was assessed in five anatomical regions by means of preserved arterial calcifications. OA was assessed using the Kellgren and Lawrence (1957) classification.

RESULTS

Statistical analysis revealed no correlation between Ath and total OA. A significant association was found for Ath and the upper limb group for OA grade >1 and for Ath and the lower limb group, consisting mainly of the hip and knee, for OA grade >2 OA.

CONCLUSIONS

The association of Ath and advanced OA of the hip and knee is comparable in prevalence to those reported in recent clinical studies, despite the low life expectancy and the different environment and lifestyle of the ancient Egyptians.

SIGNIFICANCE

This is the first study to correlate findings of Ath and OA in ancient Egypt statistically. The diseases of Ath and OA are common ailments with enormous and increasing impacts on public health.

LIMITATIONS

The large number of cardiovascular diseases was indicated only by arterial calcifications that resisted the post-mortem changes of the mummification process. Also, the assessed OA was on radiological OA.

SUGGESTIONS FOR FURTHER RESEARCH

Genomic studies of ancient Egyptian mummies may reveal genetic risk factors for Ath and OA that could be shared in ancient and modern populations.

The role of oxidation of low-density lipids in pathogenesis of osteoarthritis: A narrative review

Osteoarthritis (OA) is a chronic joint disorder that causes degeneration of cartilage, synovial inflammation, and formation of osteophytes. Aging, obesity, and sex are considered the main risk factors of OA. Recent studies have suggested that metabolic syndrome (MetS) disorders, such as hypertension, hyperlipidemia, diabetes mellitus, and obesity, may be involved in the pathogenesis and progression of OA. MetS disorders are common diseases that also result in atherosclerosis. Researchers believe that OA and atherosclerosis have underlying similar molecular mechanisms because the prevalence of both diseases increases with age. Oxidation of low-density lipoprotein (ox-LDL) is believed to play a role in the pathogenesis of atherosclerosis. Recent reports have shown that ox-LDL and low-density lipoprotein receptor 1 (LOX-1) are involved in the pathogenesis of OA. The purpose of this narrative review is to summarize the current understanding of the role of the LOX-1/ox-LDL system in the pathogenesis of OA and to reveal common underlying molecular pathways that are shared by MetS in OA and the LOX-1/ox-LDL system.

Osteoarthritis in Pseudoxanthoma Elasticum Patients: An Explorative Imaging Study

Pseudoxanthoma elasticum (PXE) is a systemic disease affecting the skin, eyes, and cardiovascular system of patients. Cardiovascular disease is associated with osteoarthritis (OA), which is the most common cause of joint pain. There is a lack of systematic investigations on joint manifestations in PXE in the literature. In this explorative study, we aimed to investigate whether patients with PXE are more at risk for developing osseous signs of OA. Patients with PXE and hospital controls with whole-body low-dose CT examinations available were included. OA was assessed using the OsteoArthritis Computed Tomography (OACT)-score, which is a 4-point Likert scale, in the acromioclavicular (AC), glenohumeral (GH), facet, hip, knee, and ankle joints. Additionally, intervertebral disc degeneration was scored. Data were analyzed using ordinal logistic regression adjusted for age, body mass index (BMI), and smoking status. In total, 106 PXE patients (age 56 (48-64), 42% males, BMI 25.3 (22.7-28.2)) and 87 hospital controls (age 55 (43-67), 46% males, BMI 26.0 (22.5-29.2)) were included. PXE patients were more likely to have a higher OA score for the AC joints (OR 2.00 (1.12-3.61)), tibiofemoral joint (OR 2.63 (1.40-5.07)), and patellofemoral joint (2.22 (1.18-4.24)). For the other joints, the prevalence and severity of OA did not differ significantly. This study suggests that patients with PXE are more likely to have structural OA of the knee and AC joints, which needs clinical confirmation in larger groups and further investigation into the mechanism.

Prevalence of multimorbid degenerative lumbar spinal stenosis with knee and/or hip osteoarthritis: protocol for a systematic review and meta-analysis

BACKGROUND

Lumbar spinal stenosis (LSS) and knee and hip osteoarthritis (OA) are prevalent conditions in the aging population and published literature suggests they share many symptoms and often are present at the same time in patients. However, no prevalence estimates of multimorbid LSS and knee and/or hip OA are currently available. The primary objective of this systematic review is therefore to estimate the prevalence of multimorbid LSS with knee and/or hip OA using radiological, clinical, and combined case definitions.

METHODS

This systematic review protocol has been designed according to the guidelines from the Cochrane Collaboration and is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols. A comprehensive search will be performed in the following databases: MEDLINE, EMBASE, CENTRAL, and CINAHL. Forward citation tracking will be performed in Web of Science. No restriction for publication date and language will be applied in the literature search, but only articles in English will be included. The search strategy will include the following domains: LSS, knee OA, and hip OA. Retrieved citations will be screened by two authors independently. Disagreements will be discussed until consensus, and a third reviewer will be consulted if consensus cannot be reached. Data extraction and assessment of risk of bias assessment will be done by two authors independently, using a standardized data extraction form and a modified risk of bias tool for prevalence studies. Meta-analysis estimating prevalence with 95% CI will be performed using a random effects model. Meta-regression analyses will be performed to investigate the impact of the following covariates: LSS clinical presentations, sample population, healthcare setting, risk of bias, and other patient characteristics on prevalence estimates for multimorbid LSS and knee and/or hip OA.

DISCUSSION

The results of this review will provide the first estimates of the prevalence of multimorbid LSS and hip and knee OA based on various case definitions. The impact of covariates such as LSS clinical presentations, sample population, healthcare setting, risk of bias, and patient characteristics on prevalence estimates will also be presented.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, awaiting registration.

Osteoarthritis

Osteoarthritis is a leading cause of disability and source of societal cost in older adults. With an ageing and increasingly obese population, this syndrome is becoming even more prevalent than in previous decades. In recent years, we have gained important insights into the cause and pathogenesis of pain in osteoarthritis. The diagnosis of osteoarthritis is clinically based despite the widespread overuse of imaging methods. Management should be tailored to the presenting individual and focus on core treatments, including self-management and education, exercise, and weight loss as relevant. Surgery should be reserved for those that have not responded appropriately to less invasive methods. Prevention and disease modification are areas being targeted by various research endeavours, which have indicated great potential thus far. This narrative Seminar provides an update on the pathogenesis, diagnosis, management, and future research on osteoarthritis for a clinical audience.