Osteoarthritis of the Knee

Ice-Inspired Lubricated Drug Delivery Particles from Microfluidic Electrospray for Osteoarthritis Treatment

Particle-based drug delivery systems have a demonstrated value in osteoarthritis treatment. Research in this area trends to developing functional particles to improve the therapeutic effects. Herein, inspired by the super lubricated surface of ice that consists of a contiguous and ultrathin layer of bound water, we developed a 2-methylacryloyloxyethyl phosphorylcholine (MPC) decorated methacrylate anhydride- hyaluronic acid (HAMA) drug delivery particle with satisfying strength and enhanced lubrication from microfluidic electrospray for osteoarthritis treatment. Benefiting from the precise control of microfluidic electrospray flows, the generated drug delivery particles are imparted with well-tailored sizes and good dispersion. As the generated HAMA particles were modified by MPC with the positively (N⁺(CH₃)₃) and negatively (PO₄^-) charged chemical groups, they were imparted with enhanced lubrication effect and reduced friction on the joint interface by forming a hydrated lubricating layer. We have demonstrated that the MPC-modified HAMA particles could be employed as microcarriers for loading diclofenac sodium (DS) to inhibit the inflammatory response, thus further enhancing the osteoarthritis therapeutic effect in vivo and in vitro. Thus, the proposed drug delivery particles with satisfactory biocompatibility and therapeutic effect are great potential for clinical applications.

1,25-Dihydroxyvitamin D Inhibits Osteoarthritis by Modulating Interaction Between Vitamin D Receptor and NLRP3 in Macrophages

Background

Osteoarthritis (OA) is the most prevalent chronic joint disease globally. Loss of extracellular matrix (ECM) by chondrocytes is a classic feature of OA. Inflammatory cytokines, such as interleukin-1β (IL-1β) and interleukin-18 (IL-18), secreted mainly by macrophages, promote expression of matrix degrading proteins and further aggravate progression of OA. 1,25-dihydroxyvitamin D (1,25VD) modulates inflammation thus exerting protective effects on cartilage tissue. However, the underlying mechanisms of 1,25VD activity have not been fully elucidated.

Methods

The destabilization of the medial meniscus (DMM)-induced mice model of OA was established to investigate the protective effects of 1,25VD by micro-CT and Safranin-O and Fast Green staining. And the co-culture system between THP-1 cells and primary chondrocytes was constructed to explore the effects of vitamin D receptor (VDR) and 1,25VD on chondrogenic proliferation, apoptosis, and migration. The immunofluorescence staining and Western blot analysis were used to detect the expressions of ECM proteins and matrix degradation-associated proteases. Enzyme-linked immunosorbent assay (ELISA) was used to examine the expression levels of inflammatory cytokines.

Results

The findings of the study showed that 1,25VD prevented cartilage degeneration and osteophyte formation by inhibiting secretion of inflammatory cytokines in OA mice model. These protective effects were exerted through the vitamin D receptor (VDR). Further studies showed that 1,25VD increased ubiquitination level of NLRP3 by binding to VDR, resulting in decrease in IL-1β and IL-18 secretion. These findings indicate that 1,25VD binds to VDR thus preventing chondrogenic ECM degradation by modulating macrophage NLRP3 activation and secretion of inflammatory cytokines, thus alleviating OA progression.

Conclusion

Here, our study suggests that 1,25VD, targeting to VDR, prevents chondrogenic ECM degradation through regulating macrophage NLRP3 activation and inflammatory cytokines secretion, thereby alleviating OA. These findings provide information on a novel molecular mechanism for application of 1,25VD as OA therapy.

Does Bisphosphonate Increase the Sclerosis of Tibial Subchondral Bone in the Progression of Knee Osteoarthritis-A Propensity Score Matching Cohort Study Based on Osteoarthritis Initiative

Bisphosphonate has great potential in KOA therapy, but whether the anti-resorption mechanism of bisphosphonate aggravates sclerosis of subchondral bone remains unclear. We found that bisphosphonate use did not increase sclerosis of subchondral bone in established KOA, perhaps resolving some concerns about bisphosphonate in patients with KOA. Introduction: Most studies have focused on the protective effect of bisphosphonate on early knee osteoarthritis (KOA) through its anti-resorption mechanism in osteoclasts. However, late KOA has a decreased rate of resorption, which is the opposite of early KOA. The risk of subchondral bone sclerosis in late KOA after using bisphosphonate has not been investigated using morphometry. Methods: Forty-five patients who had ever used bisphosphonate (or 33 patients with current use) were matched with controls through propensity matching methods, including age, body mass index (BMI), sex, health status (12-Item Short Form Survey physical health score), physical activity level (Physical Activity Scale for the Elderly score), vitamin D use, and calcium use. At the baseline and 12-month (or 18-month) follow-up, bone mineral density (BMD) of the tibia and hip was measured by dual-energy X-ray absorptiometry (DXA), and medial tibial subchondral bone morphometry: bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp) were calculated based on 3-T trabecular MRI. Data were obtained from the Bone Ancillary Study in the Osteoarthritis Initiative (OAI) project. Results: The yearly percentage change in hip BMD of the current bisphosphonate-use group was significantly greater than that of the non-bisphosphonate-use group (0.7% vs. -1%, P = 0.02). The other outcomes (BV/TV, Tb.N, Tb.Sp, Tb.Th, tibia medial BMD, and tibia lateral BMD) between the two groups presented no significant difference. The non-bisphosphonate-use group experienced a significant increase in Tb.Th [2%, 95% CI = (1%, 4%), P = 0.01], while the bisphosphonate-use group presented no significant change [1%, 95% CI = (-2%, 4%), P = 0.54]. Conclusions: Bisphosphonate use did not increase sclerosis of subchondral bone in established KOA. Bisphosphonate might have a stage-dependent effect on subchondral bone in KOA initiation and progression.

Trunk lean and toe out gait strategies impact on lower limb joints

Gait retraining as a non-invasive prospective approach to restore mechanical loading at the knee joint and slowing down knee osteoarthritis (OA) progression shows great promise. However, the impact of gait modifications such as an increase in foot progression angle (FPA) or lateral trunk lean (LTL) on the ankle and hip is not yet well understood. Thus, the goal of this study is to provide insight on the impact of FPA and LTL on the sagittal and frontal external moments at the ankle and hip of healthy participants. We hypothesize that there is an optimum, for which an increase in FPA and/or LTL minimize the knee adduction moment (KAM) without increasing significantly the frontal and sagittal external moments at the ankle and hip during gait. To test this hypothesis, 23 participants performed walking trials with modified FPA and/or LTL angles following a real-time visual feedback. The hypothesis was not confirmed and while not all the gait modifications performed by the participants in this study reduced the KAM, they significantly increased the sagittal moment at the ankle and the frontal moment at the hip. This study highlights the importance to consider the biomechanical consequences of gait modifications on the ankle and hip before considering a clinical application of gait retraining approaches.

Acupuncture for the Treatment of Knee Osteoarthritis: An Overview of Systematic Reviews

Background

Acupuncture has been widely used in the clinical management of osteoarthritis of the knee (KOA). Many systematic reviews (SRs) and meta-analyses (MAs) have reported its effectiveness in relieving pain. This overview aimed to summarize SRs and MAs on the effectiveness and safety of acupuncture for KOA and evaluate their methodological and evidence quality of the included SRs and MAs.

Methods

We conducted a comprehensive literature search for SRs and MAs in four Chinese and four international databases from their inception until August 2021. Two researchers independently searched the reviews, extracted the data, and cross-checked the data. The Assessing the Methodological Quality of Systematic Reviews 2 (AMSTAR 2) tool was used to evaluate the methodological quality of the included SRs and MAs. The Grades of Recommendations, Assessment, Development, and Evaluation (GRADE) system was used to assess the quality of evidence for the outcomes of the included SRs and MAs.

Results

A total of 14 SRs and MAs were included. The evaluation results of the AMSTAR 2 tool showed that the methodological quality of all the 14 SRs and MAs was critically low. The principal causes are the lack of a pre-registration proposal and a list of excluded studies and justify the exclusions, the report on the sources of funding, and the reasons for the study designs for inclusion. The results of the GRADE evaluation showed 25 of 46 outcomes were very low-level evidence. Seventeen were of low level, four were of moderate level and none were of high level. Most outcomes were downgraded in quality of evidence mainly because of publication bias and imprecision.

Conclusion

The existing evidence suggests that acupuncture seems to be an effective and safe therapy for KOA. However, the deficiencies in the methodological quality and quality of evidence of the included SRs/MAs have limited the reliability of the conclusions. Therefore, further rigorous and comprehensive studies are warranted to verify the effectiveness and safety of acupuncture in KOA.

Efficacy and cost-effectiveness of Stem Cell injections for symptomatic relief and strUctural improvement in people with Tibiofemoral knee OsteoaRthritis: protocol for a randomised placebo-controlled trial (the SCUlpTOR trial)

INTRODUCTION

Knee osteoarthritis (KOA) is a highly prevalent disabling joint disease. Intra-articular stem cell therapy is increasingly being used for treating KOA with little high-quality evidence to support its use. The aim of this study is to investigate the efficacy, safety and cost-effectiveness of allogeneic mesenchymal stem cells (Cymerus MSCs) for treating symptomatic tibiofemoral KOA and improving knee structure over 24 months.

METHODS AND ANALYSIS

The Stem Cell injections for symptomatic relief and strUctural improvement in people with Tibiofemoral knee OsteoaRthritis study is a phase III, multi-centre, parallel, superiority, randomised, double-blind, placebo-controlled trial, which will be conducted in Sydney and Hobart, Australia. 440 participants (220 per arm) aged over 40 years with painful KOA and mild to moderate structural change on X-ray (Kellgren and Lawrence grade 2 or 3) with medial minimum joint space width between 1 and 4 mm in the study knee will be recruited from the community and randomly allocated to receive either intra-articular MSCs or saline at baseline, week 3 and week 52. The coprimary outcomes will be the proportion of participants achieving patient-acceptable symptom state for knee pain at 24 months and quantitative central medial femorotibial compartment cartilage thickness change from baseline to 24 months. Main secondary outcomes include change in knee pain, Patient Global Assessment, physical function, quality of life and other structural changes. Additional data for cost-effectiveness analysis will also be recorded. Adverse events will be monitored throughout the study. The primary analysis will be conducted using modified intention-to-treat.

ETHICS AND DISSEMINATION

This protocol has been approved by The University of Sydney (USYD) Human Research Ethics Committee (HREC) #: 2020/119 and The University of Tasmania (UTAS) HREC #: H0021868. All participants will be required to provide informed consent. Dissemination will occur through conferences, social media, and scientific publications.

TRIAL REGISTRATION NUMBERS

Australian New Zealand Clinical Trials Registry (ACTRN12620000870954); U1111-1234-4897.

Exercise and education versus saline injections for knee osteoarthritis: a randomised controlled equivalence trial

OBJECTIVE

To compare the efficacy of an exercise and education programme with open-label placebo given as intra-articular injections of inert saline on pain and function in individuals with knee osteoarthritis (OA).

METHODS

In this open-label, randomised controlled trial, we recruited adults aged ≥50 years with symptomatic and radiographically confirmed knee OA in Denmark. Participants were randomised 1:1 to undergo an 8-week exercise and education programme or four intra-articular saline injections over 8 weeks. Primary outcome was change from baseline to week 9 in the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire pain subscale (range 0 (worst)-100 (best)). Prespecified equivalence margins of ±8 KOOS pain points were chosen for the demonstration of comparable efficacy. Key secondary outcomes were the KOOS function and quality of life subscales, and patients' global assessment of disease impact.

RESULTS

206 adults were randomly assigned: 102 to exercise and education and 104 to intra-articular saline injections. For the primary outcome, the least squares mean changes in KOOS pain were 10.0 for exercise and education and 7.3 for saline injections (difference 2.7 points, 95% CI -0.6 to 6.0; test for equivalence p=0.0008). All group differences in the key secondary outcomes respected the predefined equivalence margins. Adverse events and serious adverse events were similar in the two groups.

CONCLUSION

In individuals with knee OA, an 8-week exercise and education programme provided efficacy for symptomatic and functional improvements equivalent to that of four open-label intra-articular saline injections over 8 weeks.

TRIAL REGISTRATION NUMBER

NCT03843931.

Analysis of Serum Metabolomics in Rats with Osteoarthritis by Mass Spectrometry

Osteoarthritis is a common multifactorial chronic disease that occurs in articular cartilage, subchondral bone, and periarticular tissue. The pathogenesis of OA is still unclear. To investigate the differences in serum metabolites between OA and the control group, liquid chromatography/mass spectrometry (LC/MS)-based metabolomics was used. To reveal the pathogenesis of OA, 12 SD male rats were randomly divided into control and OA groups using collagenase to induce OA for modeling, and serum was collected 7 days after modeling for testing. The OA group was distinguished from the control group by principal component analysis and orthogonal partial least squares-discriminant analysis, and six biomarkers were finally identified. These biomarkers were metabolized through tryptophan metabolism, glutamate metabolism, nitrogen metabolism, spermidine metabolism, and fatty acid metabolism pathways. The study identified metabolites that may be altered in OA, suggesting a role in OA through relevant metabolic pathways. Metabolomics, as an important tool for studying disease mechanisms, provides useful information for studying the metabolic mechanisms of OA.

Potential New Treatments for Knee OA: A Prospective Review of Registered Trials

We aimed to evaluate potential new treatments for knee osteoarthritis (OA). The National Institute of Health ClinicalTrials.gov database was searched for “Osteoarthritis, Knee”. We found 565 ongoing interventional studies with a total planned enrollment of 111,276 subjects. Ongoing studies for knee OA represent a very small fraction of the registered clinical trials, but they are over a quarter of all knee trials and over two thirds of all OA studies. The most researched topic was arthroplasty, with aspects such as implant design changes, cementless fixation, robotic guidance, pain management, and fast track recovery. Intraarticular injections focused on cell therapies with mesenchymal stem cells sourced from adipose tissue, bone marrow, or umbilical cord. We could see the introduction of the first disease modifying drugs with an impact on knee OA, as well as new procedures such as geniculate artery embolization and geniculate nerve ablation.

The possibilities of using topical nonsteroidal anti-inflammatory drugs in the complex pain syndrome therapy of musculoskeletal system diseases

Diseases of the peripheral joints (osteoarthritis OA) and the spine are the most common pathology among other chronic conditions. One of the most common diseases characterized by degenerative periarticular changes with various clinical manifestations is periarthritis. Unlike OA, periarthritis is characterized by a discrepancy between active and passive movements, increased pain during strictly defined movements, the absence of joint swelling or local swelling in the projection of the affected tendon. As the basic therapy of OA (step 1), it is recommended to prescribe locally nonsteroidal anti-inflammatory drugs (NSAIDs), as drugs with less systemic adverse effects. Local NSAIDs have a sufficient analgesic effect in knee joints OA. Among topical NSAIDs for reducing pain in knee joints OA and periarticular tissues, diclofenac gel (Voltaren Emulgel 2%) is approved for use, the effectiveness of which has been demonstrated in many studies. To achieve maximum effect, the gel is applied according to the instructions for use of the drug: 2 ml on the anterior, posterior and lateral surfaces of the knee 2 times a day (every 12 hours) for 4 weeks.

Electroacupuncture Upregulates HIF-1α and SOX9 Expression in Knee Osteoarthritis

Electroacupuncture (EA) has been clinically used in knee osteoarthritis broadly and proved to be effective than other therapies with fewer side effects; however, the mechanism of electroacupuncture to work on cartilage remains unclear. In this study, we aimed to evaluate the effect of EA treatment on cartilage and the relationship between EA and proteins such as HIF-a and SOX9. EA (dilatational wave, 3-15 HZ, 1 mA) has been applied to bilateral Zusanli (ST36), Xuehai (SP10), Taixi (KI3), and Yanglingquan (GB34) of rats. Results showed that the cartilage of the knee osteoarthritis group had obvious damage and fissure formation while the EA group showed that the cartilage destruction was generally milder. In addition, the protein expression levels of HIF-1α, and chondrogenic markers such as Sox9, and ACAN in the electroacupuncture group were higher than those in the ACLT group. Also, the extracellular matrix protein expression levels of MMP13 and ADAMTS5 were decreased in the EA group. These findings indicate that EA could alleviate the severity of knee osteoarthritis, and HIF-a and SOX9 may closely attribute to the treatment.

G Protein-Coupled Receptors in Osteoarthritis: A Novel Perspective on Pathogenesis and Treatment

G protein-coupled receptors (GPCRs) are transmembrane receptor proteins that trigger numerous intracellular signaling pathways in response to the extracellular stimuli. The GPCRs superfamily contains enormous structural and functional diversity and mediates extensive biological processes. Until now, critical roles have been established in many diseases, including osteoarthritis (OA). Existing studies have shown that GPCRs play an important role in some OA-related pathogenesis, such as cartilage matrix degradation, synovitis, subchondral bone remodeling, and osteophyte formation. However, current pharmacological treatments are mostly symptomatic and there is a paucity of disease-modifying OA drugs so far. Targeting GPCRs is capable of inhibiting cartilage matrix degradation and synovitis and up-regulating cartilage matrix synthesis, providing a new therapeutic strategy for OA. In this review, we have comprehensively summarized the structures, biofunctions, and the novel roles of GPCRs in the pathogenesis and treatment of OA, which is expected to lay the foundation for the development of novel therapeutics against OA. Even though targeting GPCRs may ameliorate OA progression, many GPCRs-related therapeutic strategies are still in the pre-clinical stage and require further investigation.

Video-Assisted Health Education Promotes Rehabilitation Training of Total Knee Arthroplasty Patients and Reduces Stress and Burnout in Nurses Compared to Oral Education

Emerging evidence suggests video-assisted health education being an effective way in promoting rehabilitation. The present study was aimed at evaluating the effectiveness of video-assisted health education in promoting rehabilitation training in postoperative OA patients and at comparing it with oral education. This study was a noncontemporaneous control study involving 179 patients who underwent TKA. For the intervention group, a bedside interactive system that recorded a series of educational videos showing a rehabilitation training program was established. For the control group, oral education having the same content as that in the videos for the intervention group was provided. After education, clinical outcomes such as occurrence of complications, circulating biomarkers of inflammation, and rehabilitation progress of the patients were obtained. Furthermore, job stress and burnout in nurses who participated in the present study were assessed. Results showed that C-reactive protein levels of patients were significantly lower in the intervention group than in the control group (84.54 ± 36.09 vs. 99.45 ± 31.73 mg/L, P = 0.004). Faster achievement of postoperative knee flexion to 90 degrees (21.31 ± 5.83 vs. 35.72 ± 9.93 h, P < 0.001) and first ambulation (19.91 ± 4.57 vs. 50.15 ± 7.00 h, P < 0.001), reduced number of postoperative complications such as postoperative orthostatic intolerance (7 vs. 19, P = 0.008) and constipation (10 vs. 23, P = 0.009), and reduced length of hospital stay (7.51 ± 1.79 vs. 8.21 ± 2.15 days, P = 0.019) in the intervention group in comparison to the control group were noted. Emotional exhaustion and burnout of nurses were reduced significantly in the intervention group than in the control group (21.00 ± 8.04 vs. 36.50 ± 11.22, P = 0.002; 55.90 ± 11.57 vs. 85.50 ± 6.80, P < 0.001, respectively). Reduced personal accomplishments in nurses were improved significantly in the intervention group when compared with the control group (41.90 ± 4.91 vs. 32.80 ± 7.07, P = 0.004). We concluded that video-assisted health education may promote TKA patient recovery and reduce burnout and stress in nurses when compared with oral education. Video-assisted health education could be helpful in situation where manpower of nurse is in shortage.

Low-level laser therapy and static stretching exercises for patients with knee osteoarthritis: A randomised controlled trial

OBJECTIVES

To investigate the laser effect associated with stretching exercise on pain and functionality in patients with knee osteoarthritis.

DESIGN

A randomised controlled trial.

SETTING

Special Rehabilitation Services.

SUBJECTS

We enrolled 215 knee osteoarthritis patients (430 knees were treated).

INTERVENTION

Group Laser + Stretch (n = 43), Placebo + Stretch (n = 43), Stretch (n = 43), Laser (n = 43) and Control (n = 43) were treated with active laser and stretching exercises; placebo laser and stretching exercises; stretching exercises; active laser, and control, respectively. Interventions were conducted 3 times a week for 8 or 11 weeks.

MAIN OUTCOME MEASURES

The primary outcome was the change in knee pain and disability. Secondary outcomes included severity of osteoarthritis, mobility, knee range of motion, flexibility, activity, severity of osteoarthritis and medication intake for pain relief.

RESULTS

The patients' average age was 63.52 (6.8) years. Pain scores at baseline and post treatment (p < 0.001) were 7.43 (2.10) and 2.79 (1.92) for group Laser + Stretch, 7.39 (1.98) and 4.47 (2.82) for group Placebo + Stretch, 6.83 (1.42) and 4.24 (2.43) for group Stretch, 6.61 (1.68) and 2.94 (2.65) for group Laser, 6.74 (1.75) and 6.47 (2.29) for group Control, respectively. Disability score at baseline and post treatment (p = 0.000237) were 12.36 (5.02) and 8.08 (4.64) for group Laser + Stretch, 12.71 (5.12) and 9.90 (4.95) for group Placebo + Stretch, 11.83 (2.77) and 7.20 (5.28) for group Stretch, 11.58 (5.59) and 8.21 (6.18) for group Laser, 11.23 (4.68) and 11.45 (4.83) for group Control, respectively.

CONCLUSION

Laser therapy combined with stretching exercises improves pain during rest, activities of daily living, stiffness, muscle shortening and range of motion in patients with knee osteoarthritis.

Proprioceptive Training for Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: There is increased interest in proprioceptive training for knee osteoarthritis (KOA). However, little consensus supports the effectiveness of this intervention. Objective: This meta-analysis aimed to assess the effects of proprioceptive training on symptoms, function, and proprioception in people with KOA. Methods: The PubMed, Cochrane Library, Web of Science, and EMBASE databases were systematically searched from the inception dates to April 16, 2021 for relevant randomized controlled trials (RCTs). Data were pooled by calculating the standardized mean differences (SMDs) and 95% confidence intervals (CIs). A random-effects model was used for the analyses. Results: A total of 24 RCTs involving 1,275 participants were included in our analysis. This study indicated that compared to no intervention, proprioceptive training significantly improved pain, stiffness, physical function, joint position sense (JPS), muscle strength, mobility, and knee ROM (P < 0.05) in people with KOA. When compared to other non-proprioceptive training, proprioceptive training provided better results in terms of JPS (SMD = -1.28, 95%CI: [-1.64, -0.92], I 2 = 0%, P < 0.00001) and mobility (timed walk over spongy surface) (SMD = -0.76, 95%CI: [-1.33, -0.18], I 2 = 64%, P = 0.01), and other results are similar. When proprioceptive training plus other non-proprioceptive training compared to other non-proprioceptive training, the two groups showed similar outcomes, but there was a greater improvement for JPS (SMD = -1.54, 95%CI: [-2.74, -0.34], I 2 = 79%, P = 0.01), physical function (SMD = -0.34, 95%CI: [-0.56, -0.12], I 2 = 0%, P = 0.003), and knee ROM (P < 0.05) in the proprioceptive training plus other non-proprioceptive training group. When proprioceptive training plus conventional physiotherapy compared against conventional physiotherapy, the two groups demonstrated similar outcomes, but there was a significant improvement for JPS (SMD = -0.95, 95%CI: [-1.73, -0.18], I 2 = 78%, P = 0.02) in the proprioceptive training plus conventional physiotherapy group. Conclusions: Proprioceptive training is safe and effective in treating KOA. There is some evidence that proprioceptive training combined with general non-proprioceptive training or conventional physiotherapy appears to be more effective and should be considered as part of the rehabilitation program. However, given that the majority of current studies investigated the short-term effect of these proprioceptive training programs, more large-scale and well-designed studies with long-term follow up are needed to determine the long-term effects of these proprioceptive training regimes in KOA. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/#recordDetails, PROSPERO, identifier: CRD42021240587.

MAPK inhibitors protect against early‑stage osteoarthritis by activating autophagy

Osteoarthritis (OA) is a chronic, age-related osteoarthropathy that causes a considerable decline in quality of life, as well as economic losses due to its high incidence and poor prognosis. Mitogen-activated protein kinases (MAPKs) regulate multiple cellular processes, including proliferation, differentiation and apoptosis, in certain diseases, such as cancer, diabetes and Alzheimer's disease. The present study aimed to investigate the regulatory role of the MAPK signaling pathway in early-stage OA. A rabbit model of early-stage OA was induced by treatment with the enzyme papain. U0126 [an extracellular signal-regulated kinase (ERK) inhibitor], SP600125 [a Jun NH2-terminal kinase (JNK) inhibitor] and SB203580 (a p38 inhibitor) were administered to the rabbits via intra-articular injection. The severity of OA was assessed by histological examination using H&E, toluidine blue and safranin-O/fast green staining, as well by analyzing the glycosaminoglycan (GAG) content and determining the OA Research Society International (OARSI) score. Western blotting was used to detect the protein expression levels of matrix metalloproteinase-3 (MMP3), ERK, phosphorylated (p)-ERK, p38, p-p38, JNK, p-JNK, Beclin1, UNC-51-like kinase 1 (ULK1) and microtubule-associated protein 1 light chain 3 (LC3)II/I. U0126, SP600125 or SB203580 treatment significantly decreased the OARSI scores and significantly increased the GAG levels in the cartilaginous tissues of OA model rabbits. These results indicated that the MAPK inhibitors reduced the severity of OA-induced injury at the early stage. Western blotting results demonstrated that MAPK inhibition significantly decreased the protein expression levels of MMP3 in OA cartilage. The protective effect of MAPK inhibitors in OA was mediated via the activation of autophagy, as demonstrated by the increased protein expression levels of LC3II/I, ULK1 and Beclin1. Overall, the data indicated that MAPK inhibitors may exert a protective effect against OA by restoring compromised autophagy. Furthermore, the present study suggested that MAPK inhibitors may represent a potential pharmacological strategy for treating OA in the future.

Targeted treatment for osteoarthritis: drugs and delivery system

The management of osteoarthritis (OA) is a clinical challenge due to the particular avascular, dense, and occluded tissue structure. Despite numerous clinical reports and animal studies, the pathogenesis and progression of OA are still not fully understood. On the basis of traditional drugs, a large number of new drugs have been continuously developed. Intra-articular (IA) administration for OA hastens the development of targeted drug delivery systems (DDS). OA drugs modification and the synthesis of bioadaptive carriers contribute to a qualitative leap in the efficacy of IA treatment. Nanoparticles (NPs) are demonstrated credible improvement of drug penetration and retention in OA. Targeted nanomaterial delivery systems show the prominent biocompatibility and drug loading-release ability. This article reviews different drugs and nanomaterial delivery systems for IA treatment of OA, in an attempt to resolve the inconsonance between in vitro and in vivo release, and explore more interactions between drugs and nanocarriers, so as to open up new horizons for the treatment of OA.

Molecular Classification of Knee Osteoarthritis

Knee osteoarthritis (KOA) is the most common form of joint degeneration with increasing prevalence and incidence in recent decades. KOA is a molecular disorder characterized by the interplay of numerous molecules, a considerable number of which can be detected in body fluids, including synovial fluid, urine, and blood. However, the current diagnosis and treatment of KOA mainly rely on clinical and imaging manifestations, neglecting its molecular pathophysiology. The mismatch between participants' molecular characteristics and drug therapeutic mechanisms might explain the failure of some disease-modifying drugs in clinical trials. Hence, according to the temporal alteration of representative molecules, we propose a novel molecular classification of KOA divided into pre-KOA, early KOA, progressive KOA, and end-stage KOA. Then, progressive KOA is furtherly divided into four subtypes as cartilage degradation-driven, bone remodeling-driven, inflammation-driven, and pain-driven subtype, based on the major pathophysiology in patient clusters. Multiple clinical findings of representatively investigated molecules in recent years will be reviewed and categorized. This molecular classification allows for the prediction of high-risk KOA individuals, the diagnosis of early KOA patients, the assessment of therapeutic efficacy, and in particular, the selection of homogenous patients who may benefit most from the appropriate therapeutic agents.

The trajectories of depression symptoms and comorbidity in knee osteoarthritis subjects

BACKGROUND

Previous cross-sectional studies have demonstrated the high prevalence of depression and comorbidity in knee osteoarthritis (KOA), and KOA or its impact on lifestyle was seen as a potential trigger factor of depression and comorbidity. However, the exact onset and progression pattern of depression and comorbidity in KOA was still unknown.

METHODS

Group-based trajectory modeling (GBTM) analysis was conducted in the 2833 subjects selected from the osteoarthritis initiative (OAI) database. Eight-year trajectories were determined and described. Baseline characteristics were investigated in multi-variable regression to detect the risk factors of the unfavored trajectory.

RESULTS

Stable trajectory (70.4%) and worsening trajectory (29.6%) were identified in comorbidity. The risk factors for the worsening trajectory membership were the obesity (OR = 1.47 CI = [1.20, 1.79], P < 0.001), older age (OR = 1.74, CI = [1.41, 2.16], P < 0.001), and smoke (OR = 1.30, CI = [1.08, 1.57], P < 0.01) at baseline. Stable trajectory (52.0%), slow-worsening trajectory (40.5%), and fast-worsening trajectory (7.5%) were identified in depression symptoms. The risk factors for the fast-worsening trajectory membership were female (OR = 1.51 CI = [1.03, 2.20], P < 0.05), lower income (OR = 1.52, CI = [1.01, 2.27], P < 0.05), and smoke (OR = 1.30, CI = [1.08, 1.57], P < 0.01) at baseline.

CONCLUSION

A significant amount of KOA subjects tends to develop depression symptoms and comorbidity. Managing related risk factors, like weight loss or smoking cessation, might have considerable significance in preventing or delaying depression symptoms and comorbidity in KOA. Key Points • The first study investigating the trajectory of comorbidity progression in KOA. • Approximately 7.5% of KOA patients tend to develop depression symptoms quite rapidly, and 30% of KOA patients tend to develop comorbidity • Risk factors of worsening trajectories were identified: obesity, older age, smoking, female, and lower income.

Curcumenol mitigates chondrocyte inflammation by inhibiting the NF‑κB and MAPK pathways, and ameliorates DMM‑induced OA in mice

At present, an increasing number of individuals are affected by osteoarthritis (OA), resulting in a heavy socioeconomic burden. OA in knee joints is caused by the release of inflammatory cytokines and subsequent biomechanical and structural deterioration. To determine its anti‑inflammatory function, the current study investigated the use of the plant‑derived medicine, curcumenol, in OA treatment. Curcumenol was not cytotoxic to ATDC5 chondrocytes and primary chondrocytes, as determined using a cell viability test. When these cells were treated with TNF‑α and IL‑1β to induce inflammation, curcumenol treatment inhibited the progression of inflammation by inactivating the NF‑κB and MAPK signaling pathways, as well as decreasing the expression levels of MMP3 (as indicated by reverse transcription‑quantitative PCR and western blotting). Moreover, to analyze metabolic and catabolic status in high‑density and pellet culture, catalytic changes and the degradation of the extracellular matrix induced by TNF‑α and IL‑1β, were evaluated by alcian blue staining. These catalytic deteriorations were ameliorated by curcumenol. Using curcumenol in disease management, the mechanical and metabolic disruption of cartilage caused in the destabilization of medial meniscus (DMM) model was prevented in vivo. Thus, curcumenol mitigated inflammation in ATDC5 chondrocytes and primary mice chondrocytes, and also ameliorated OA in a DMM‑induced mouse model.

Sprifermin: a recombinant human fibroblast growth factor 18 for the treatment of knee osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a serious and incurable disease leading the disability. Surgical treatment is the last but not necessarily the best approach for patients with high risks and costs. However, there are no disease-modifying OA drugs (DMOADs) developed for the disease so far, leaving a huge unmet need for drug treatments. Sprifermin is a recombinant human fibroblast growth factor 18 (rhFGF18) and has been confirmed to have anabolic effects on articular cartilage, which makes it a promising DMOAD.

AREAS COVERED

The content of this review includes overview of the market, discovery and development, molecular mechanism, preclinical studies, clinical efficacy, safety, and tolerability of sprifermin. It examines the potential of sprifermin as a disease modifying drug for the treatment of knee OA.

EXPERT OPINION

Sprifermin could be one of the most promising DMOADs, especially for cartilage phenotype. Current studies show good tolerability and no safety concerns. Well-designed phase 3 clinical trials are required to examine its effects on symptoms and cartilage loss in knee OA.

The Role of Extracellular Vesicles in the Pathogenesis, Diagnosis, and Treatment of Osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease that affects the entire joint and has been a tremendous burden on the health care system worldwide. Although cell therapy has made significant progress in the treatment of OA and cartilage regeneration, there are still a series of problems. Recently, more and more evidence shows that extracellular vesicles (EVs) play an important role in the progression and treatment of OA. Here, we discuss that EVs from different cell sources not only participate in OA progression, but can also be used as effective tools for the diagnosis and treatment of OA. In addition, cell pretreatment strategies and EV tissue engineering play an increasingly prominent role in the field of OA treatment. This article will systematically review the latest developments in these areas. As stated above, it may provide new insights for improving OA and cartilage regeneration.

The incidence and risk factors of contralateral knee arthroplasty after primary unilateral unicompartmental knee arthroplasty

Unicompartmental knee arthroplasty (UKA) is one of the commonly used surgical methods for unicompartmental osteoarthritis in recent years. Although the prognosis of the operated knee has been widely studied, there are relatively little data on the natural history of the contralateral knee after unilateral replacement. The aim of this study was to explore the incidence and risk factors of consequential knee arthroplasty in patients with bilateral knee osteoarthritis (KOA) after receiving primary unilateral UKA, so as to provide a theoretical basis for making a more comprehensive treatment strategy for patients with KOA.We conducted a retrospective study and enrolled patients with bilateral KOA received unilateral UKA from June 2015 to December 2019 in the third department of joint orthopedics, the third hospital of Hebei Medical University. The patients were divided into replacement group and non-replacement group according to whether the contralateral knee joint received knee arthroplasty. Information about treatment of contralateral knee joint was collected from medical records to determine the incidence. Univariate analysis and multivariate logistic regression analysis were performed to identify the independent risk factors.A total of 502 patients were enrolled in this study. The incidence of contralateral knee arthroplasty was 38.64%. In the univariate analysis, vertical angle of mechanical axis, knee joint's internal and external joint space, Kellgren-Lawrence (K-L) classification, femoral tibial angle were the significant risk factors for contralateral knee arthroplasty. In the multivariate model, only vertical angle of mechanical axis ≥3.03° (odds ratio [OR] 4.36, 95% confidence interval [CI], 2.47-9.11), K-L classification grades 3 and 4 (OR 2.46,3.72; 95%CI, 1.31-4.25, 1.98-6.87), and femoral tibial angle ≥187.32° (OR 6.32, 95%, 2.23-18.87) remained associated with the occurrence of knee arthroplasty.About a quarter of patients with bilateral KOA received unilateral UKA will receive contralateral knee arthroplasty. Higher K-L classification, femoral tibial angle, and mechanical axis vertical angle are identified risk factors.

Medium-term efficacy of arthroscopic debridement vs conservative treatment for knee osteoarthritis of Kellgren-Lawrence grades I-III

BACKGROUND

Arthroscopic debridement is a mature treatment for knee osteoarthritis (KOA). Due to the differences in the research subjects, methods, and efficacy evaluation indexes, there are great differences in the surgical efficacy reported in the literature.

AIM

To compare the medium-term efficacy of arthroscopic debridement and conservative treatment for KOA of Kellgren-Lawrence grades I-III.

METHODS

Patients with KOA of Kellgren-Lawrence grades I-III who were admitted to the orthopedic clinic of our hospital from July 2018 to December 2018 and agreed to undergo arthroscopic surgery were included in an arthroscopic debridement group, and those who refused surgical treatment were included in a conservative treatment group. Gender, age, body mass index (BMI), side of KOA, American hospital for special surgery knee score (HSS score) before treatment, visual analogue scale (VAS) score during walking and rest before treatment, conservative treatment content, and surgical procedure were recorded. Outpatient visits were conducted at the 1^st, 3^rd, 6^th, 12^th, and 24^th mo after treatment in the two groups. The changes of HSS score and VAS score in each group before and after treatment were statistically analyzed, and the differences of HSS score and VAS score in different treatment stages between the two groups were also compared.

RESULTS

In the conservative treatment group, there were 80 patients with complete follow-up data, including 20 males and 60 females, aged 58.75 ± 14.66 years old. And in the knee arthroscopic debridement group, there were 98 patients with complete follow-up data, including 24 males and 74 females, aged 59.27 ± 14.48 years old. There was no statistically significant difference in the general data (gender, age, BMI, side of KOA, Kellgren-Lawrence grade distribution, HSS score, and VAS score) between the two groups before treatment. The HSS scores of the conservative treatment group at the 1^st, 3^rd, 6^th, 12^th, and 24^th mo after treatment were significantly higher than that before treatment (P < 0.05). There was no statistical difference in HSS score of the conservative treatment group among the 1^st, 3^rd, 6^th, 12^th, and 24^th mo (P > 0.05). The HSS score of the knee arthroscopic debridement group at the 1^st mo after surgery was significantly higher than that before surgery (P < 0.05). HSS scores of the knee arthroscopic debridement group at the 3^rd, 6^th, 12^th, and 24^th mo were significantly higher than those before surgery and at the 1^st mo after surgery (P < 0.05). There were no statistically significant differences in HSS scores at the 3^rd, 6^th, 12^th, and 24^th mo after surgery (P > 0.05). HSS scores at the 3^rd, 6^th, 12^th, and 24^th mo were significantly higher in the arthroscopic debridement group than in the conservative treatment group (P < 0.05). There was no statistical difference in HSS scores between the two groups before treatment and at the 1^st mo of follow-up (P > 0.05). VAS scores during walking and rest were significantly decreased in both groups, and the VAS score during rest was significantly lower in the arthroscopic debridement group than in the conservative treatment group, but there was no significant difference in the VAS score during walking between the two groups after treatment.

CONCLUSION

Compared with conservative treatment, arthroscopic debridement can significantly improve the knee resting pain and knee functional status of patients with KOA of Kellgren-Lawrence grades I-III within 2 years after treatment.

IRE1-mTOR-PERK Axis Coordinates Autophagy and ER Stress-Apoptosis Induced by P2X7-Mediated Ca2+ Influx in Osteoarthritis

Moderate-intensity exercise can help delay the development of osteoarthritis (OA). Previous studies have shown that the purinergic receptor P2X ligand gated ion channel 7 (P2X7) is involved in OA development and progression. To investigate the effect of exercise on P2X7 activation and downstream signaling in OA, we used the anterior cruciate ligament transection (ACLT)-induced OA rat model and primary chondrocyte culture system. Our in vivo experiments confirmed that treadmill exercise increased P2X7 expression and that this effect was more pronounced at the later time points. Furthermore, P2X7 activation induced endoplasmic reticulum (ER) stress and increased the expression levels of ER stress markers, such as 78 kDa glucose-regulated protein (GRP78), protein kinase R-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme-1 (IRE1), and activating transcription factor 6 (ATF6). At the early time points, IRE1 and PERK were activated, and mTOR was inhibited. At the later time points, mTOR was activated, mediating PERK to promote ER stress-apoptosis, whereas IRE1 and autophagy were inhibited. To confirm our observations in vitro, we treated primary chondrocytes with the P2X7 agonist benzoylbenzoyl-ATP (Bz-ATP). Our results confirmed that P2X7-mediated Ca²⁺ influx activated IRE1-mediated autophagic flux and induced PERK-mediated ER stress-apoptosis. To further investigate the role of P2X7 in OA, we injected mTOR antagonist rapamycin or P2X7 antagonist A740003 into the knee joints of ACLT rats. Our results demonstrated that mTOR inhibition induced autophagy, decreased apoptosis, and reduced cartilage loss. However, injection of mTOR agonist MHY1485 or Bz-ATP had the opposite effect. In summary, our results indicated that during the early stages of moderate-intensity exercise, P2X7 was activated and autophagic flux was increased, delaying OA development. At the later stages, P2X7 became over-activated, and the number of apoptotic cells increased, promoting OA development. We propose that the IRE1-mTOR-PERK signaling axis was involved in the regulation of autophagy inhibition and the induction of apoptosis. Our findings provide novel insights into the positive and preventative effects of exercise on OA, suggesting that the intensity and duration of exercise play a critical role. We also demonstrated that on a molecular level, P2X7 and its downstream pathways could be potential therapeutic targets for OA.

HTR2B and SLC5A3 Are Specific Markers in Age-Related Osteoarthritis and Involved in Apoptosis and Inflammation of Osteoarthritis Synovial Cells

Objective: Osteoarthritis (OA) is a heterogeneous age-related disease, which is badly difficult to cure due to its complex regulatory networks of pathogenesis. This study explored OA-specific genes in synovial tissues and validated their roles on apoptosis and inflammation of OA synovial cells.

Methods: Weighted correlation network analysis (WGCNA) was employed to explore OA-related co-expression modules in the GSE55235 and GSE55457 datasets. Then, this study screened OA-specific genes. After validation of these genes in the GSE12021 and GSE32317 datasets, HTR2B and SLC5A3 were obtained. Their expression was detected in human OA and healthy synovial tissues by RT-qPCR and western blot. OA rat models were constructed by anterior cruciate ligament transection (ACLT) operation. In OA synovial cells, HTR2B and SLC5A3 proteins were examined via western blot. After transfection with sh-HTR2B or sh-SLC5A3, apoptosis and inflammation of OA synovial cells were investigated by flow cytometry and western blot.

Results: A total of 17 OA-specific DEGs were identified, which were significantly enriched in inflammation pathways. Among them, HTR2B and SLC5A3 were highly expressed in end-than early-stage OA. Their up-regulation was validated in human OA synovial tissues and ACLT-induced OA synovial cells. Knockdown of HTR2B and SLC5A3 restrained apoptosis and increased TGF-β and IL-4 expression as well as reduced TNF-α and IL-1β expression in OA synovial cells.

Conclusion: Collectively, this study identified two OA-specific markers HTR2B and SLC5A3 and their knockdown ameliorated apoptosis and inflammation of OA synovial cells.

Expression of Piezo mRNA is unaffected in a rat model of knee osteoarthritis

Osteoarthritis of the knee impairs activities of daily living of those affected. Its irreversible degenerative changes to the knee joint induce functional disturbance and unpleasant arthralgia. The pain has inflammatory components and often is manifested with mechanical allodynia and hyperalgesia. Sustained weight bearing and joint movements increase pain sensitivity in knee osteoarthritis. Understanding the mechanisms underlying the mechanical allodynia and hyperalgesia might provide a therapeutical target for pain relief in patients with such symptoms. Piezo channel is a mechanically activated ion channel that may be involved in mechanical transduction in the articular cartilage. Although it has been shown that inflammation potentiates Piezo channel current induced by mechanical stimulation, whether Piezo expression levels are influenced by knee osteoarthritis has remained unknown. We measured Piezo mRNA in knee joints and dorsal root ganglia after establishing a model of knee osteoarthritis in rats using monosodium iodoacetate and found Piezo mRNA level is not upregulated. This finding raises a question as whether and how Piezo channels may be involved in mechanically induced pain in osteoarthritis.

Acupoint injection in improving pain and joint function of knee osteoarthritis patients: A protocol for systematic review and meta-analysis

BACKGROUND

Knee osteoarthritis is a common chronic progressive disease, which seriously affects the quality of life of the middle-aged and elderly, and even leads to disability. More and more evidence shows that acupoint injection is beneficial to the clinical treatment of knee osteoarthritis, but there are differences in the efficacy of different acupoints and injection drugs, and there is no systematic review to assess this therapy at present. The purpose of this study is to systematically evaluate the efficacy and safety of acupoint injection in improving pain and joint function in patients with knee osteoathrosis.

METHODS

According to the retrieval strategy, we will search from CNKI, Wanfang, VIP, Chinese Biomedical Science, PubMed, Embase, Web of Science and the Cochrane Library for randomized controlled trials of acupoint injection in the treatment of knee osteoarthritis from the establishment of the database to February 2021. The study will be screened according to the inclusion and exclusion criteria, and the Cochrane risk bias assessment tool will be used to evaluate the quality of the study. Revman 5.4 software is used for meta-analysis.

RESULTS

This study will evaluate the efficacy of acupoint injection in the treatment of knee osteoarthritis by evaluating the total effective rate, the degree of pain relief, joint function score, adverse reactions, and so on.

CONCLUSION

This study will provide reliable evidence-based basis for the clinical application of acupoint injection in the treatment of knee osteoarthritis.

ETHICS AND DISSEMINATION

Private information from individuals will not be published. This systematic review also does not involve endangering participant rights. Ethical approval will not be required. The results may be published in a peer-reviewed journal or disseminated at relevant conferences.OSF Registration number-doi: 10.17605/OSF.IO/M5FTK.

Comprehensive Review of Knee Osteoarthritis Pharmacological Treatment and the Latest Professional Societies' Guidelines

Osteoarthritis is the most common musculoskeletal progressive disease, with the knee as the most commonly affected joint in the human body. While several new medications are still under research, many symptomatic therapy options, such as analgesics (opioid and non-opioid), nonsteroid anti-inflammatory drugs, symptomatic slow-acting drugs in osteoarthritis, and preparations for topical administration, are being used, with a diverse clinical response and inconsistent conclusions across various professional societies guidelines. The concept of pharmacogenomic-guided therapy, which lies on principles of the right medication for the right patient in the right dose at the right time, can significantly increase the patient’s response to symptom relief therapy in knee osteoarthritis. Corticosteroid intra-articular injections and hyaluronic acid injections provoke numerous discussions and disagreements among different guidelines, even though they are currently used in daily clinical practice. Biological options, such as platelet-rich plasma and mesenchymal stem cell injections, have shown good results in the treatment of osteoarthritis symptoms, greatly increasing the patient’s quality of life, especially when combined with other therapeutic options. Non-inclusion of the latter therapies in the guidelines, and their inconsistent stance on numerous therapy options, requires larger and well-designed studies to examine the true effects of these therapies and update the existing guidelines.

Mechanistic insights into AMPK-SIRT3 positive feedback loop-mediated chondrocyte mitochondrial quality control in osteoarthritis pathogenesis

Osteoarthritis (OA) is a major cause of disability in the elderly population and represents a significant public health problem and socioeconomic burden worldwide. However, no disease-modifying therapeutics are currently available for OA due to an insufficient understanding of the pathogenesis of this disability. As a unique cell type in cartilage, chondrocytes are essential for cartilage homeostasis and play a critical role in OA pathogenesis. Mitochondria are important metabolic centers in chondrocytes and contribute to cell survival, and mitochondrial quality control (MQC) is an emerging mechanism for maintaining cell homeostasis. An increasing number of recent studies have demonstrated that dysregulation of the key processes of chondrocyte MQC, which involve mitochondrial redox, biogenesis, dynamics, and mitophagy, is associated with OA pathogenesis and can be regulated by the chondroprotective molecules 5' adenosine monophosphate-activated protein kinase (AMPK) and sirtuin 3 (SIRT3). Moreover, AMPK and SIRT3 regulate each other, and their expression and activity are always consistent in chondrocytes, which suggests the existence of an AMPK-SIRT3 positive feedback loop (PFL). Although the precise mechanisms are not fully elucidated and need further validation, the current literature indicates that this AMPK-SIRT3 PFL regulates OA development and progression, at least partially by mediating chondrocyte MQC. Therefore, understanding the mechanisms of AMPK-SIRT3 PFL-mediated chondrocyte MQC in OA pathogenesis might yield new ideas and potential targets for subsequent research on the OA pathomechanism and therapeutics.