Molecular Classification of Knee Osteoarthritis

A thorough analysis of data on the correlation between IL-16 polymorphisms and the susceptibility to knee osteoarthritis: A meta-analysis

BACKGROUND

Knee osteoarthritis (KOA) is a multifactorial condition affected by genetic and environmental factors. Studies have explored the relationship between IL-16 genetic polymorphisms and KOA risk, but findings have been inconclusive. This meta-analysis seeks to assess the association between IL-16 polymorphisms and KOA risk.

METHODS

A systematic literature search was conducted in several databases, including PubMed, Web of Science, EMBASE, SciELO, and CNKI, for studies published until June 1, 2024. Two independent researchers identified peer-reviewed articles in English, Portuguese, and Chinese using keywords related to "Knee Osteoarthritis" and "Interleukin 16." Relevant references were also manually reviewed for additional studies. Pooled odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated to assess the association strength. Additionally, minor allele frequencies (MAFs), Hardy-Weinberg equilibrium (HWE) data, heterogeneity, publication bias, and Newcastle-Ottawa scores (NOS) were evaluated.

RESULTS

This analysis included 15 case-control studies, encompassing 1747 individuals with KOA and 1627 healthy controls. Within these studies, five investigated the genetic variations rs11556218 (584 cases, 542 controls), rs4778889 (583 cases, 543 controls), and rs4072111 (580 cases, 542 controls). The findings suggest that the IL-16 variants rs11556218 and rs4072111 may offer protection against KOA development, while no link exists between the rs4778889 variant and KOA susceptibility. The variability in IL-16 polymorphisms, particularly in Asian and Chinese populations, indicates different genetic associations with KOA risk. Strong results, supported by sensitivity analyses and the absence of significant publication bias, emphasize the influence of study methods on the relationship between these polymorphisms and KOA risk.

CONCLUSIONS

The analysis of three polymorphisms-rs11556218, rs4778889, and rs4072111-shows varying associations with KOA. Rs11556218 and rs4072111 offer protective effects in non-Asian populations, while rs4778889 shows no significant association across cohorts. Notably, rs11556218 and rs4072111 do not correlate with KOA susceptibility in Asian and Chinese populations, suggesting ethnic differences in genetic influences on KOA.

Beyond symptomatic alignment: evaluating the integration of causal mechanisms in matching animal models with human pathotypes in osteoarthritis research

Osteoarthritis (OA) is a highly prevalent and disabling condition lacking curative treatments, with only symptomatic relief available. Recognizing OA as a heterogenous disorder with diverse aetiologies and molecular foundations underscores the need to classify patients by both phenotypes and molecular pathomechanisms (endotypes). Such stratification could enable the development of targeted therapies to surmount existing treatment barriers. From a scientific, economic, and ethical perspective, it is crucial to employ animal models that accurately represent the endotype of the target patient population, not merely their clinical symptoms. These models must also account for intrinsic and extrinsic factors, like age, sex, metabolic status, and comorbidities, which impact OA's pathogenesis and its clinical and molecular variability and can profoundly influence not only structural and symptomatic disease severity and progression but also the underlying molecular pathophysiology. The molecular definition of the OA subpopulation must also be reflected in the read-outs, as the traditional methods-macroscopic and histological scoring, along with limited gene expression profiling of established biomarkers for cartilage degradation, extracellular matrix (ECM) turnover, and synovial inflammation-are inadequate for discovering new, phenotype- and endotype-specific biomarkers or therapeutic targets. Thus, animal model characterisation should evolve to include both clinically and pathophysiologically pertinent measures of disease progression and response to treatment. This review evaluates the utility and accuracy of current animal models in OA research, focusing on their capacity to replicate the disease's pathophysiological processes.

Patients with Higher Pulse Wave Velocity Are More Likely to Develop a More Severe Form of Knee Osteoarthritis: Implications for Cardiovascular Risk

Background/Objectives: Knee osteoarthritis (KOA) is a progressive degenerative joint disease characterised by low-grade inflammation and is associated with increased cardiovascular (CV) risk and arterial stiffness. Pulse wave velocity (PWV) is a quantitative measure of arterial stiffness and an important tool for detecting subclinical arterial calcification and CV risk. This study aimed to determine whether PWV can distinguish radiographically mild KOA (Kellgren-Lawrence grades 1-2) from severe KAO (Kellgren-Lawrence grades 3-4) in terms of CV risk factors. Methods: A total of 223 postmenopausal women with KOA participated in this cross-sectional study. Assessments included anthropometry, laboratory analyses, blood pressure and PWV measurements, a 6 min walk test, pain evaluation using a visual analogue scale (VAS), and completion of the International Physical Activity Questionnaire (IPAQ). Results: PWV was significantly higher in the severe KOA group (10.53 m/s vs. 8.78 m/s, p < 0.001). A cut-off value of 8.4 m/s effectively distinguished between severe and mild forms of KOA (AUC = 0.798, p = 0.001). OA grade, pain, age, waist circumference, WHR, SCORE 2/SCORE 2OP, systolic blood pressure, serum glucose, HbA1c, uric acid, creatinine, and erythrocyte sedimentation rate were increased in the group with PWV > 8.4 m/s, compared to the group with PWV ≤ 8.4 m/s. Conversely, eGFR, the 6 min walk test and physical activity of patients were reduced in the group with PWV > 8.4 m/s. A patient with a PWV > 8.4 m/s has a 1.77 times higher chance of developing a more severe form of the disease than a patient with a lower PWV. Conclusions: Patients with a higher PWV are more likely to develop a more severe form of KOA, which is associated with increased cardiovascular risk.

Mediating Role of the ANGPTL3/TFPI Protein Ratio in Regulating T-Cell Surface Glycoprotein CD5 Levels on Knee Osteoarthritis (KOA): A Mendelian Randomization Study

This study utilized Mendelian randomization (MR) to investigate the impact of inflammatory proteins on knee osteoarthritis (KOA), measured using the ratio of protein levels (rQTLs). The primary objective was to identify potential intervention targets to mitigate KOA progression. Data from 2821 rQTLs, 91 inflammatory proteins, and KOA-related genetic variations were obtained through genome-wide association studies (GWAS). Bidirectional MR identified rQTLs with unidirectional causal relationships with KOA. Further analyses included false discovery rate (FDR) correction, colocalization, and mediation analysis. Two inflammatory proteins were found to be associated with KOA: T-cell surface glycoprotein CD5 [OR (95% CI) = 0.867 (0.760-0.990), PIVW = 0.035] and C-X-C motif chemokine 9 [OR (95% CI) = 1.150 (1.001-1.320), PIVW = 0.048]. Variations in their levels influenced rQTLs, producing differential effects on KOA. Specifically, rQTL-ANGPTL3/TFPI (human recombinant angiopoietin-like protein 3/Tissue factor pathway inhibitor) was identified as a mediator in the effect of T-cell surface glycoprotein CD5 levels on KOA. T-cell surface glycoprotein CD5 levels were negatively correlated with rQTL-ANGPTL3/TFPI (β1 = -0.084), while rQTL-ANGPTL3/TFPI was positively correlated with KOA (β2 = 0.159). These findings align with the total effect, where T-cell surface glycoprotein CD5 levels were negatively associated with KOA (β = -0.143). Thus, rQTL-ANGPTL3/TFPI may serve as a reliable mediator in the pathway through which T-cell surface glycoprotein CD5 levels affect KOA. This mediator may not only represent a potential therapeutic target but also serve as a biomarker for assessing KOA treatment efficacy, offering a novel direction for KOA diagnosis and management.

Efficacy of arthroscopic cartilage transplantation combined with platelet-rich plasma in the treatment of early knee osteoarthritis: a retrospective cohort study

BACKGROUND

Knee osteoarthritis (KOA) is a common degenerative disease that leads to functional decline in the knee joint and a significant reduction in quality of life. Arthroscopic cartilage transplantation combined with platelet-rich plasma (ACT-PRP) has emerged as a novel treatment method and is gradually being applied to patients with early KOA. This study aimed to evaluate the therapeutic efficacy of ACT-PRP compared to conventional conservative treatment.

METHODS

Patients diagnosed with KOA who were treated in the Department of Orthopedics at the First People's Hospital of Lianyungang from January 2020 to January 2022 were included in the study. Patients were divided into two groups: the ACT-PRP group, receiving arthroscopic cartilage transplantation combined with PRP, and the conservative treatment group, receiving standard conservative treatment. All patients were followed for six months, and knee function and pain relief were assessed using the Lysholm score, IKDC score, KOOS, and VAS.

RESULTS

A total of 113 patients were enrolled, with 43 in the ACT-PRP group and 70 in the conservative treatment group. Baseline characteristics showed no significant differences (P > 0.05). At the final follow-up, the ACT-PRP group showed greater improvements in knee function and pain relief compared to the conservative treatment group, with significantly higher Lysholm score (P < 0.001), IKDC score (P < 0.001), and KOOS (P < 0.001), and lower VAS (P < 0.001). These findings suggest the ACT-PRP approach is more effective for early knee osteoarthritis.

CONCLUSIONS

Arthroscopic cartilage transplantation combined with platelet-rich plasma is significantly superior to conventional conservative treatment in improving knee function, alleviating pain, and enhancing patient satisfaction, making it a recommended option for early KOA.

Advance signal processing and machine learning approach for analysis and classification of knee osteoarthritis vibroarthrographic signals

Osteoarthritis is a common cause of disability among elderly significantly affecting their quality of life due to pain and functional limitations. This study proposes a novel, non-invasive, and cost-effective diagnostic technique using vibroarthrography (VAG) for early detection and grading of knee osteoarthritis (KOA) overcoming the limitations of traditional methods like X-rays, CT scans, and MRIs. Signal acquisition involved capturing of VAG signals from KOA patients using Thinklabs One digital stethoscope and a specialized knee brace within a frequency range of 20 Hz to 2000 Hz with a ± 3 dB tolerance at 44,000 samples per second. Various signal processing techniques, like time domain, statistical, PSD, wavelet, and Hilbert-Huang transform analysis, were used to study the resultant signal. Subsequently, a novel combination of self-organizing maps (SOMs) and K-means clustering was proposed to categorize VAG signals into distinct OA grade clusters. The resulting analysis identified distinct patterns in the time domain correlating with joint alteration severity. A SD/Mean ratio differentiated OA grades. Hilbert-Huang Transform established intrinsic mode functions relating frequency bands to OA stages, while wavelet and spectrogram analysis demonstrated increased signal complexity and variability with disease progression. The effectiveness of proposed clustering model was indicated by high mean Silhouette Coefficient (∼0.80) and low Davies-Bouldin Index (∼0.33) indicating distinct and accurate segmentation of OA stages. These findings clearly highlighted the potential of SOMs and K-means clustering in analysing VAG signals for classifying into different KOA grades. These results demonstrate the substantial potential of advanced signal processing, SOMs, and K-means clustering in uncovering complex patterns in VAG data, linking increasing knee sound signal complexity with OA progression. This highlights the potential of our approach in medical diagnostics, especially for chronic conditions like KOA, where early detection and ongoing monitoring are crucial.

Research progress and prospect of MAPK signaling pathway in knee osteoarthritis

The knee joint, one of the most vulnerable joints in the human body, is susceptible to degenerative changes due to factors such as aging, obesity, trauma, inflammation, and genetic predisposition. These factors contribute to primary or secondary degeneration of knee joint cartilage and bone hyperplasia. Knee osteoarthritis (KOA), a prevalent condition particularly among the elderly, significantly impacts patients' quality of life. Aberrant activation of cellular signaling pathways, namely the NF-κB, MAPK, and Wnt pathways, has been identified as a key factor in the pathogenesis of KOA. These pathways contribute to inflammation, cartilage degradation, and disruption of the anabolic-catabolic balance within articular cartilage. Understanding the precise roles of these pathways is crucial for developing targeted therapies to prevent and treat knee OA. Therefore, further exploration of the pathogenesis of knee osteoarthritis is essential to develop more effective therapeutic strategies.

JP4-039 protects chondrocytes from ferroptosis to attenuate osteoarthritis progression by promoting Pink1/Parkin-dependent mitophagy

Background

Osteoarthritis (OA) is the most common degenerative joint disease, and its main pathological mechanism is articular cartilage degeneration. The purpose of this study was to investigate the role of mitophagy in the pathogenesis of chondrocyte ferroptosis in OA.

Methods

The expressions of ferroptosis related proteins (GPX4, FTH1, COX2) and ubiquitin-dependent mitophagy related proteins (PARKIN, PINK1) in the intact and injured areas of OA cartilage were analyzed. Nitro oxide JP4-039, a mitochondrial targeting antioxidant, has bifunctional role of targeting mitochondria. Then we evaluated the potential protective effect of JP4-039 in OA using the destabilization of medial meniscus (DMM)-induced OA model, as well as tert-butyl hydrogen peroxide (TBHP)-treated primary mouse chondrocytes and human cartilage explants.

Results

The concentrations of iron and lipid peroxidation and the expression of ferroptosis drivers in the damaged areas of human OA cartilages were significantly higher than those in the intact cartilage. Pink1/Parkin-dependent mitophagy decreased in the injured area of human OA cartilage and was negatively correlated with ferroptosis. Then, the toxicity and effectiveness of JP4-039 are tested to determine its working concentration. Next, at the molecular biological level, we found that JP4-039 showed the effect of anti-chondrocyte ferroptosis. Moreover, it was verified on DMM-induced OA model mice, that JP4-039 could delay the progression of OA. Finally, JP4-039 was re-verified in vivo and in vitro to inhibit chondrocyte ferroptosis and delay the progression of OA by promoting Pink1/Parkin-dependent mitophagy.

Conclusion

JP4-039 inhibits ferroptosis of chondrocytes by promoting Pink1/Parkin-dependent mitophagy and delays OA progression.

Injectable Chondroitin Sulfate Microspheres with Gallic Acid-Magnesium MOF for Anti-Inflammatory and Cartilage Degeneration Alleviation in Osteoarthritis Treatment

Inflammation and cartilage degeneration are critical challenges in osteoarthritis (OA) treatment. Achieving sustained drug efficacy while mitigating the adverse effects of inflammation and reactive oxygen species remains a significant challenge. This study synthesizes a gallic acid-magnesium (GA-Mg) metal-organic framework (MOF) as a drug carrier for puerarin (PA). The PA-loaded GA-Mg MOF (pGM) is encapsulated within chondroitin sulfate methacrylate, forming monodisperse hybrid microspheres (CM@pGM) under ultraviolet light using microfluidic technology. The pGM is physically confined within the microspheres through a network of structural obstructions and noncovalent interactions. During degradation, GA and Mg2+ ions release from pGM, improving the inflammatory microenvironment of the articular cavity and mitigating oxidative stress. The sustained release of Mg2+ and PA supports chondrocyte anabolism and facilitates cartilage repair. In vitro studies confirm that injectable microspheres extend the drug release period to over 2 weeks. In vivo experiments demonstrate that CM@pGM significantly reduces osteophyte formation, alleviates degenerative changes in articular cartilage, and delays OA progression. In conclusion, CM@pGM, as a drug delivery platform that ameliorates the inflammatory microenvironment, alleviates oxidative stress, and promotes cartilage repair, holds significant potential for OA treatment.

MSCs-EVs harboring OA immune memory reprogram macrophage phenotype via modulation of the mt-ND3/NADH-CoQ axis for OA treatment

BACKGROUND

Osteoarthritis (OA) is a prevalent degenerative joint disease and current therapies are insufficient to halt its progression. Mesenchymal stem cells-derived extracellular vesicles (MSCs-EVs) offer promising therapeutic potential for OA treatment, and their efficacy can be enhanced through strategic engineering approaches.

METHODS

Inspired by the immune memory of the adaptive immune system, we developed an engineered strategy to impart OA-specific immune memory to MSCs-EVs. Using Luminex technology, inflammatory factors (IFN-γ, IL-6, and TNF-α), which mimic the OA inflammatory microenvironment, were identified and used to prime MSCs, generating immune memory-bearing MSCs-EVs (iEVs). Proteomic analysis and complementary experiments were conducted to evaluate iEVs' effects on macrophage phenotypic reprogramming.

RESULTS

iEVs, particularly IL-6-EV, exhibited potent immunoregulatory functions along with the ability to modulate mitochondrial metabolism. Both in vitro and in vivo, IL-6-EV significantly reprogrammed macrophages towards the M2 subtype, effectively suppressing articular inflammation and OA progression. Mechanistic studies revealed that IL-6-EV facilitated M2 polarization by regulating mitochondrial oxidative phosphorylation via the mt-ND3/NADH-CoQ axis.

CONCLUSION

This study introduces a strategy to enhance MSCs-EVs' therapeutic efficacy in OA. Multi-omics analysis and biological validation demonstrate its potential, providing new insights for MSCs-EVs' future application in OA and other clinical conditions.

Clinical research progress of umbilical cord blood mesenchymal stem cells in Knee articular cartilage repair: A review

Umbilical cord blood mesenchymal stem cells (UCB-MSCs) are a type of adult stem cell with multipotent differentiation potential and immunoregulatory functions, primarily found in neonatal cord blood. Due to their noninvasive collection method, abundance, and ease of preservation, UCB-MSCs represent a promising biological material. This review examines the clinical research on UCB-MSCs in knee articular cartilage repair, highlighting their regenerative potential for treating knee joint cartilage defects. Our aim is to provide insights into current applications and propose directions for future research, focusing on optimizing clinical use and enhancing patient outcomes.

Hydrogen-oxygen mixture inhalation as an adjunctive treatment to home-based exercise in older patients with knee osteoarthritis: an open-label, blinded-endpoint, randomized controlled trial

Objective

Knee osteoarthritis (KOA) is a degenerative joint condition, leading to disability and diminished quality of life. Molecular hydrogen has been proven to have antioxidant and anti-inflammatory properties, but few studies have investigated its effects on osteoarthritis. Our study aims to assess the therapeutic potential of hydrogen-oxygen mixture (H2-O2) inhalation for KOA.

Methods

In this randomized controlled trial, eligible elderly KOA patients were randomly assigned to either Group H or Group C. Both groups participated in a 12-week home-based exercise (HBE) program, which included knee-joint exercises and health education. Group H additionally received H2-O2 inhalation for 60 min per day over 2 weeks, while Group C did not. The primary outcome was measured using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Secondary outcomes included inflammation levels (hs-CRP, NLR, PLR, LMR), Chair Stand Test (CST), Timed Up and Go (TUG), 36-item short-form health survey (SF-36), Exercise Adherence Rating Scale (EARS), and adverse events.

Results

A total of 121 subjects were enrolled, with an average age of 81.2 years, and 80.2% were female. The between-group mean difference in the WOMAC total score was -5.2 (95% CI -12.1 to 1.7, P = 0.140) at week 12, with Group H showing an improvement of -22.9 (95% CI -26.3 to -19.6, P < 0.001) and Group C showing an improvement of -19.4 (95% CI -22.7 to -16.0, P < 0.001) compared to baseline, revealing a significant group × time interaction (F (3, 356.034) = 14.425, P < 0.001). No significant differences were observed between both groups at week 12 in CST, TUG, SF-36 scores, EARS scores, or the incidence of adverse events.

Conclusion

Although clinical significance was not achieved, H2-O2 inhalation alleviated KOA symptoms and enhanced functional activity in elderly patients undergoing the HBE program during the initial 2 weeks. However, its sustained effects on improving KOA symptoms were not observed.

Duhuo Jisheng Decoction in reduction of inflammatory response via Transforming growth factor-β/Smad signaling pathway for repairing rabbit articular cartilage Injury: A Randomized Controlled Trial

OBJECTIVE

This study aims to investigate the mechanism underlying the effect of Duhuo Jisheng Decoction on the repair of rabbit articular cartilage injury through a reduction in the inflammatory response mediated by the Transforming growth factor (TGF)-β/Smad signaling pathway.

METHODS

A rabbit articular cartilage injury model was constructed using a ring bone extraction drill. Twenty-four Japanese white rabbits were randomly divided into six groups, namely Sham operation, model, low-dose Duhuo Jisheng Decoction, medium-dose Duhuo Jisheng Decoction, high-dose Duhuo Jisheng Decoction, and positive control groups. The treatment lasted 12 weeks. Gross observation, International Cartilage Repair Society score, Wakitani score, and Micro-computed tomography analysis were used to evaluate the structural repair of cartilage injury. Histology and immunohistochemistry were used to observe the proteoglycan, P-TβRII, P-Smad2, and type II collagen expression levels. Enzyme-linked immunosorbent assay was used to analyze the concentrations of Matrix Metalloproteinase-13 and Syndecan-4 in the joint fluid; and RT-PCR and Western Blot were used to observe the mRNA and protein expressions of ALK5, Sox-9, P-Smad3, and TGF-β1 at the injury repair site.

RESULTS

The repair effect of cartilage injury, as seen through gross observation and quantitative scoring, was better in all the Duhuo Jisheng Decoction treatment groups than in the model group. The medium dose group of Duhuo Jisheng Decoction had the best repair effect. We observed remarkable structural restoration of cartilage injury in the medium-dose Duhuo Jisheng Decoction group, with the subchondral bone presenting a distinct hierarchy, and parameters such as bone volume fraction and trabecular separation/spacing being significantly augmented. We found high expression levels of proteoglycans, P-TβRII, P-Smad2, and type II collagen. The concentrations of Matrix Metalloproteinase-13 and Syndecan-4 in the joint fluid were significantly lower following treatment. The low gene expression levels of ALK5, Sox-9, P-Smad3, and TGF-β1 in the injury site of the model group could be reversed in the medium-dose Duhuo Jisheng Decoction group.

CONCLUSION

Duhuo Jisheng Decoction can repair rabbit cartilage injury and reverse the levels of inflammatory factors in the joint fluid. The mechanism underlying its therapeutic effect is related to the activation of the TGF-β/Smad signaling pathway. This study provides a reliable basis for using Duhuo Jisheng Decoction to treat cartilage injury following knee osteoarthritis.

Extracellular Vesicles: A Novel Diagnostic Tool and Potential Therapeutic Approach for Equine Osteoarthritis

Osteoarthritis (OA) is a chronic progressive degenerative joint disease that affects a significant portion of the equine population and humans worldwide. Current treatment options for equine OA are limited and incompletely curative. Horses provide an excellent large-animal model for studying human OA. Recent advances in the field of regenerative medicine have led to the exploration of extracellular vesicles (EVs)-cargoes of microRNA, proteins, lipids, and nucleic acids-to evaluate their diagnostic value in terms of disease progression and severity, as well as a potential cell-free therapeutic approach for equine OA. EVs transmit molecular signals that influence various biological processes, including the inflammatory response, apoptosis, proliferation, and cell communication. In the present review, we summarize recent advances in the isolation and identification of EVs, the use of their biologically active components as biomarkers, and the distribution of the gap junction protein connexin 43. Moreover, we highlight the role of mesenchymal stem cell-derived EVs as a potential therapeutic tool for equine musculoskeletal disorders. This review aims to provide a comprehensive overview of the current understanding of the pathogenesis, diagnosis, and treatment strategies for OA. In particular, the roles of EVs as biomarkers in synovial fluid, chondrocytes, and plasma for the early detection of equine OA are discussed.

Comparative Analysis of Osteoarthritis Therapeutics: A Justification for Harnessing Retrospective Strategies via an Inverted Pyramid Model Approach

In this review, we seek to explore two distinct approaches to the clinical management of OA: a prospective approach, addressing primarily one's genetic predisposition to OA and generating early intervention options, and the retrospective approach, aimed at halting or reversing OA progression post-symptom onset. The clinical management of OA remains challenging, largely due to the limited availability of preventative treatments and failure of existing therapies to modify or reverse the underlying pathophysiology. The prospective approach involves the identification of genetic markers associated with OA and utilizes in vitro and in vivo models to characterize the underlying disease mechanism. Further, this approach focuses on identifying genetic predispositions and unique molecular subtypes of OA to develop individualized treatment plans based on patient genotypes. While the current literature investigating this strategy has been notable, this approach faces substantial challenges, such as extensive time burdens and utilization of extensive genetic testing that may not be economically feasible. Additionally, there is questionable justification for such extensive investigations, given OA's relatively low mortality rates and burden when contrasted with diseases like specific forms of cancer, which rely heavily on the prospective approach. Alternatively, the retrospective approach primarily focuses on intervention following symptom onset and aims to utilize novel therapeutics to slow or reverse the inflammatory cascade typically seen in disease progression. These treatments, like Hippo pathway inhibitors, have shown initial promise in halting OA progression and alleviating OA symptomology by modulating cellular processes to preserve articular cartilage. In comparison to the prospective approach, the retrospective strategy is likely more cost-effective, more widely applicable, and does not necessitate thorough and invasive genetic screening. However, this approach must still be weighed against the typical natural history of disease progression, which frequently results in total knee arthroplasty and unacceptable outcomes for 15-20% of patients. From a comparative analysis of these two approaches, this review argues that the retrospective strategy, with ideally lower time and economic burden and greater accessibility, offers a more reasonable and effective solution in the context of OA management. Using a similar approach to other management of chronic diseases, we suggest an "Inverted Pyramid" model algorithm, a structured research and development regimen that prioritizes generating widely effective therapies first, with subsequent refinement of treatments based on the development of patient resistance to these therapies. We argue that this strategy may reduce the need for total knee arthroplasty while improving patient outcomes and accessibility.

Promoting chondrogenesis by targeted delivery to the degenerating cartilage in early treatment of osteoarthritis

Osteoarthritis (OA) is a highly incident total joint degenerative disease with cartilage degeneration as the primary pathogenesis. The cartilage matrix is mainly composed of collagen, a matrix protein with a hallmark triple-helix structure, which unfolds with collagen degradation on the cartilage surface. A collagen hybridizing peptide (CHP) is a synthetic peptide that binds the denatured collagen triple helix, conferring a potential disease-targeting possibility for early-stage OA. Here, we constructed an albumin nanoparticle (An) conjugated with CHP, loaded with a chondrogenesis-promoting small molecule drug, kartogenin (KGN). The CHP-KGN-An particle exhibited sustained release of KGN in vitro and prolonged in vivo retention selectively within the degenerated cartilage in the knee joints of model mice with early-stage OA. Compared to treatment with KGN alone, CHP-KGN-An robustly attenuated cartilage degradation, synovitis, osteophyte formation, and subchondral bone sclerosis in OA model mice and exhibited a more prominent effect on physical activity improvement and pain alleviation. Our study showcases that targeting the degenerated cartilage by collagen hybridization can remarkably promote the efficacy of small molecule drugs and may provide a novel delivery strategy for early-stage OA therapeutics.

Promotion and Mechanism of Acupotomy on Chondrocyte Autophagy in Knee Osteoarthritis Rabbits

OBJECTIVE

To explore the effect of acupotomy intervention on autophagy of chondrocytes in rabbits with knee osteoarthritis (KOA), and to determine the possible mechanisms of acupotomy to alleviate cartilage degeneration.

METHODS

The modified Videman method was used to construct a KOA rabbit model. After modeling, 40 rabbits were randomly divided into 4 groups by a random number table: control; KOA (model); KOA + acupotomy (acupotomy), and KOA + sham acupotomy (sham), 10 in each group. After a 3-week treatment course, the knee joint activity was determined by the modified Lequesne MG index. Hematoxylin-eosin staining staining was used to examine the morphological changes of chondrocytes. Autophagy of chondrocytes was observed by transmission electron microscopy. The surface morphology of cartilage tissue was observed by scanning electron microscope. The mRNA and protein levels of AMP kinase/mammalian target of rapamycin/Unc-51 (AMPK/mTOR/ULK1) signal pathway key proteins, autophagy-related factor Beclin-1 and microtubule-associated protein 1A/1B light chain 3 (LC3) in rabbit knee cartilage were assessed by real-time fluorescence quantitative polymerase chain reaction and Western blot, respectively.

RESULTS

The modified Lequesne MG score of acupotomy group was significantly lower than that of model group (P<0.05). Pathological results showed that chondrocyte autophagy decreased and cartilage surface was rough in the model group, which recovered after acupotomy treatment. The mRNA expressions of AMPK, ULK1, Beclin-1 and the protein levels of p-AMPK, p-ULK1, Beclin-1, and LC3 II/LC3 I were decreased in the model group, while the mRNA and protein expressions of mTOR were increased (P<0.01). However, acupotomy treatment reversed these abnormal changes (P<0.05).

CONCLUSIONS

Acupotomy could effectively up-regulate the expressions of AMPK, ULK1 and Beclin1, reduce the expression of mTOR, promote autophagy, and alleviate joint degeneration. Acupotomy is a promising complementary and alternative therapy for KOA.

POU Class 2 Homeobox Associating Factor 1, as a Hub Candidate Gene in OP, Relieves Osteoblast Apoptosis

Increasing evidence suggests that osteoblast apoptosis contributes to the pathogenesis of postmenopausal osteoporosis (PMOP). This study aimed to identify a hub gene associated with osteoporosis (OP) progression and its functions. We utilized the GSE68303 expression dataset from GEO database and conducted weighted gene co-expression network analysis (WGCNA) to investigate changes in co-expressed genes between sham and ovariectomy (OVX) groups. Differentially expressed genes (DEGs) were identified using the "limma" R package on GSE68303 dataset. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using the DAVID database. A protein-protein interaction (PPI) network was constructed using the STRING database, which was visualized by Cytoscape software. The top ten hub genes were screened using the Cytohubba plugin, among which POU class 2 homeobox associating factor 1 (POU2AF1), an OP-related hub gene, showed a significant increase in OVX-induced mouse model based on immunohistochemical staining. Inhibition of POU2AF1 suppressed cell viability, induced cell cycle arrest at the G1 phase, and promoted osteoblast apoptosis as demonstrated by CCK-8 assay, flow cytometry analysis, and TUNEL assay. Moreover, overexpression of POU2AF1 decreased cleaved caspase-3/-8/-9 expression while increasing cyclinD1 and Ki67 expression in MC3T3-E1 and hFOB1.19 cells. Therefore, POU2AF1 may serve as a potential diagnostic biomarker for slowing down the progression of OP.

Melatonin Alleviates Osteoarthritis by Regulating NADPH Oxidase 4-Induced Ferroptosis and Mitigating Mitochondrial Dysfunction

Recent evidence indicates that the damaged regions in osteoarthritis are accompanied by the accumulation of iron ions. Ferroptosis, as an iron-dependent form of cell death, holds significant implications in osteoarthritis. Melatonin, a natural product with strong scavenging abilities against reactive oxygen species and lipid peroxidation, plays a crucial role in the treatment of osteoarthritis. This study aims to demonstrate the existence of ferroptosis in osteoarthritis and explore the specific mechanism of melatonin in suppressing ferroptosis and alleviating osteoarthritis. Our findings reveal that melatonin reverses inflammation-induced oxidative stress and lipid peroxidation while promoting the expression of extracellular matrix components in chondrocytes, safeguarding the cells. Our research has revealed that NADPH oxidase 4 (NOX4) serves as a crucial molecule in the ferroptosis process of osteoarthritis. Specifically, NOX4 is located on mitochondria in chondrocytes, which can induce disorders in mitochondrial energy metabolism and dysfunction, thereby intensifying oxidative stress and lipid peroxidation. LC-MS analysis further uncovered that GRP78 is a downstream binding protein of NOX4. NOX4 induces ferroptosis by weakening GRP78's protective effect on GPX4 and reducing its expression. Melatonin can inhibit the upregulation of NOX4 on mitochondria and mitigate mitochondrial dysfunction, effectively suppressing ferroptosis and alleviating osteoarthritis. This suggests that melatonin therapy represents a promising new approach for the treatment of osteoarthritis.

Predictive Factors for Total Knee Arthroplasty: An Observational Study

Introduction Knee osteoarthritis (KOA) is the most common form of osteoarthritis. It is diagnosed based on clinical symptoms, physical examination, and imaging, most frequently by knee X-ray in at least two views. In front of a patient with early KOA, all the predictive factors and risk factors that can be modified, but also that can lead to a rapid evolution of the symptoms and the need for total knee arthroplasty (TKA), must be taken into account and identified. There were a series of prognostic factors associated with KOA, such as age, sex, BMI, degree of physical activity, decrease in bone mineral density, C-reactive protein, malalignment, clinical severity at baseline, and previous traumas. The treatment of KOA is varied and involves pharmacological and non-pharmacological measures and surgical treatment in the final stages of evolution. Materials and methods In the University Emergency Hospital of Bucharest, Bucharest, Romania, patients with KOA presented to the Department of Orthopedics and Traumatology, and those who required surgical treatment, such as TKA, arthroscopy, or non-surgical treatment, were enrolled. We conducted a descriptive and prospective observational study that included 70 patients clinically and imaging diagnosed with KOA. The inclusion criteria consisted of a patient over 45 years old with knee pain and radiological signs of KOA. The exclusion criteria referred to patients with recent traumatic history, signs of active osteoarticular infection, the lack of radiological changes of KOA that imposed the differential diagnosis, patients known to have rheumatological diseases in the Algic phase, and patients in whom it was not possible to collect complete required data. Results Patients who required TKA were older (65.12 ± 8.19 years) than patients who required other therapeutic interventions (52.55 ± 3.63 years), the difference of 12.57 years being statistically significant (t = -8.882, p ≤ 0.001). Women were more than three times more likely to require TKA than men (80.85% vs. 52.17%, OR = 3.87, CI [1.29, 11.56]). Patients with HBP were more than four times more likely to require TKA than patients without HBP (78.57% vs. 42.86%, OR = 4.88, CI [1.42, 16.82]). Patients with elevated ESR were more than 26 times more likely to require TKA than patients with normal ESR (96.67% vs. 52.50%, OR = 26.23, CI [3.25, 211.67]). There are statistically significant differences between the non-TKA group (mean rank = 60.20) and TKA patients' score (mean rank = 25.62) (U = 6.000, Z = -6.606, p ≤ 0.001). Thus, patients who required TKA had a significantly lower KSS score than patients who required other treatments. Conclusion According to the data obtained in the studied group of patients, the characteristics of the patient at high risk of requiring TKA are the following: a female patient over 65 years of age who associates hypertension, high ESR, and fibrinogen values ​​with KSS score and KSS function with low values, recording an average value of 56.70.

Dicoumarol attenuates NLRP3 inflammasome activation to inhibit inflammation and fibrosis in knee osteoarthritis

Knee osteoarthritis (KOA) is a major cause of disability in elderly individuals. Dicoumarol is a coumarin‑like compound derived from sweet clover [Melilotus officinalis (L.) Pall]. It has been suggested that dicoumarol exhibits various types of pharmacological activities, including anticoagulant, antitumor and antibacterial effects. Due to its various biological activities, dicoumarol has a potential protective effect against OA. Therefore, the present study aimed to assess the effects of dicoumarol on knee osteoarthritis. In the present study, dicoumarol was found to protect rat synoviocytes from lipopolysaccharide (LPS)‑induced cell apoptosis. Western blot analysis showed that dicoumarol significantly reduced the protein expression levels of fibrosis‑related markers and inflammatory cytokines (Tgfb, Timp, Col1a, Il1b and Il18). The inhibitory rates of these proteins were all >50% (P<0.01) compared with those in the LPS and ATP‑induced group. Consistently, the mRNA expression levels of these markers and cytokines were decreased to normal levels by dicoumarol after the treatment of rat synovial fibroblasts with LPS and ATP. Mechanistic studies demonstrated that dicoumarol did not affect NF‑κB signaling, but it did directly interact with NOD‑like receptor protein 3 (NLRP3) to promote its protein degradation, which could be reversed by MG132, but not NH4Cl. The protein half‑life of NLRP3 was accelerated from 26.1 to 4.3 h by dicoumarol. Subsequently, dicoumarol could alleviate KOA in vivo; knee joint diameter was decreased from 11.03 to 9.93 mm. Furthermore, the inflammation and fibrosis of the knee joints were inhibited in rats. In conclusion, the present findings demonstrated that dicoumarol could impede the progression of KOA by inhibiting NLRP3 activation, providing a potential treatment strategy for KOA.

Diagnostic biomarkers in knee osteoarthritis: Based on bioinformatics and experimental verification in vivo and in vitro

BACKGROUND

Knee osteoarthritis (KOA) is a multifactorial whole-joint disease with a high rate of disability. Considering the complexity of KOA, there is an urgent need to discover new molecular pathological markers and multi-target treatment strategies.

METHODS

Two datasets, GSE51588 and GSE57218, were downloaded from the Gene Expression Omnibus database and screened for differentially expressed genes (DEGs) using the Gene Expression Omnibus 2R (GEO2R). Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of DEGs were performed. A protein-protein interaction (PPI) network was constructed and hub genes were identified using Molecular Complex Detection (MCODE). Receiver-operating characteristic curves (ROC) were plotted for the genes, and their prognostic values were evaluated. The expression levels of the hub genes in the monosodium iodoacetate (MIA)-induced KOA rat model and lipopolysaccharide (LPS)-stimulated C28/I2 cells were verified using reverse transcription quantitative real-time PCR (RT-qPCR).

RESULTS

Overall, 33 DEGs were up-regulated and 6 DEGs were down-regulated in the two datasets. A total of 12 hub genes were identified, including COL15A1, THY1, COL1A1, COL5A1, CTHRC1, MXRA5, FN1, COL1A2, COL3A1, SPARC, COL8A1, and COL2A1, which all could be used as biomarkers to differentiate KOA samples from healthy controls. More importantly, we found that THY1, CTHRC1, SPARC, and COL8A1 were significantly upregulated in vivo and in vitro compared with the controls (p < .01).

CONCLUSIONS

The expression levels of THY1, CTHRC1, SPARC, and COL8A1 were elevated and had good prognostic values as biomarkers in KOA.

Pterostilbene Protects against Osteoarthritis through NLRP3 Inflammasome Inactivation and Improves Gut Microbiota as Evidenced by In Vivo and In Vitro Studies

Osteoarthritis (OA) is a persistent inflammatory disease, and long-term clinical treatment often leads to side effects. In this study, we evaluated pterostilbene (PT), a natural anti-inflammatory substance, for its protective effects and safety during prolonged use on OA. Results showed that PT alleviated the loss of chondrocytes and widened the narrow joint space in an octacalcium phosphate (OCP)-induced OA mouse model (n = 3). In vitro experiments demonstrate that PT reduced NLRP3 inflammation activation (relative protein expression: C: 1 ± 0.09, lipopolysaccharide (LPS): 1.14 ± 0.07, PT: 0.91 ± 0.07, LPS + PT: 0.68 ± 0.04) and the release of inflammatory cytokines through NF-κB signaling inactivation (relative protein expression: C: 1 ± 0.03, LPS: 3.49 ± 0.02, PT: 0.66 ± 0.08, LPS + PT: 2.78 ± 0.05), ultimately preventing cartilage catabolism. Interestingly, PT also altered gut microbiota by reducing inflammation-associated flora and increasing the abundance of healthy bacteria in OA groups. Collectively, these results suggest that the PT can be considered as a protective strategy for OA.

Safety and Efficacy of Hybrid Cooperative Complexes of Sodium Hyaluronate and Sodium Chondroitin for the Treatment of Patients with Symptomatic Knee Osteoarthritis

INTRODUCTION

Knee osteoarthritis (KOA) represents a widespread degenerative disease that causes pain and motor disability. Conservative treatments mainly focus on relieving symptoms, improving joint function, and trying to delay surgery. Safety and efficacy of hybrid cooperative complexes (2.4% sodium hyaluronate and 1.6% sodium chondroitin; HA-SC) for symptomatic KOA were investigated in a single-arm, prospective, pilot study.

METHODS

Patients with a visual analogue scale (VAS) pain score ≥ 4 and Kellgren-Lawrence Grade < 4 received a single intraarticular HA-SC injection. Patients with a VAS score change from baseline ≤ 1 received a second injection at day 30. Device-related adverse events (DR-AEs)/adverse events (AEs) were primary endpoints. Secondary endpoints included Western Ontario and McMaster Universities Osteoarthritis Index LK 3.1 (WOMAC LK 3.1), VAS, patient global assessment of disease status (PtGA), and patient proportion needing a second injection.

RESULTS

Of 83 patients with KOA (Kellgren-Lawrence Grade, 2-3), 34.9% had DR-AEs at day 7. No serious DR-AEs/AEs were reported. A significant (P < 0.0001) reduction over time in VAS pain score plus WOMAC pain, stiffness, physical function limitation, and total scores was reported. Median PtGA scores indicated a 'slight improvement' at most follow-up visits. Only 18.1% of patients required a second injection.

CONCLUSIONS

A single intraarticular HA-SC injection was safe, well-tolerated, and did not lead to major deterioration in terms of reducing knee pain, stiffness, and physical function limitation in patients with symptomatic KOA.

Phenotypic Classification and Functional Assessment in Knee Osteoarthritis Patients

The purpose of our study was the phenotypic classification of patients with osteoarthritis of the knee (KOA) and the dynamic assessment of functional status, monitored both numerically and in conformity with the International Classification of Functioning, Disability, and Health (ICF-basic set, shortened form). We conducted a prospective study in the Department of Physical Medicine and Rehabilitation, Filantropia Hospital, Craiova, from June of 2022 to November of 2023. In total, 100 patients with KOA were enlisted. Using data from the literature, physiotherapeutic examination, and results from paraclinical examinations, we classified studied patients into the five phenotypic categories: chronic pain (F1), local pathology with predominance of inflammatory mechanisms (F2), local pathology with predominance of metabolic mechanisms of bone and cartilage structures (F3), metabolic disorders (F4) and comorbidities (F5)-primarily chronic venous insufficiency in the lower limbs. We analyzed the values of generic qualifiers (at two evaluation time points) for the most significant elements of the core ICF set, abbreviated form, used in OAG, across each of the five phenotypes. Phenotypes F4 and F5 showed significant improvements across all evaluated functions, indicating increased efficacy in patients with comorbidities and metabolic diseases. Reduction in pain sensation, improvement in joint and muscle mobility, as well as enhancements in functions related to walking, dressing, and hand use, reflect an overall improvement in the quality of life for these patients.

Gentiopicroside ameliorates the lipopolysaccharide-induced inflammatory response and hypertrophy in chondrocytes

PURPOSE

This study aimed to evaluate the protective effects of gentiopicroside against lipopolysaccharide-induced chondrocyte inflammation.

METHODS

SW 1353 chondrosarcoma cells were stimulated with LPS (5 μg/ml) for 24 h and treated with different concentrations of gentiopicroside (GPS) for 24 h. The toxic effects of GPS on chondrocytes were determined using a CCK-8 assay and EdU staining. Western blotting, qPCR, and immunofluorescence analysis were used to examine the protective effect of GPS against the inflammatory response in chondrocytes induced by lipopolysaccharide (LPS). One-way ANOVA was used to compare the differences between the groups (significance level of 0.05).

RESULTS

The CCK-8 results showed that 10, 20 and 40 μM GPS had no significant toxic effects on chondrocytes; GPS effectively reduced the production of IL-1β and PGE2, reversed LPS-induced extracellular matrix degradation in cartilage by inhibiting the Stat3/Runx2 signaling pathway, and suppressed the hypertrophic transformation of SW 1353 chondrosarcoma cells.

CONCLUSION

Our study demonstrated that GPS significantly inhibited the LPS-induced inflammatory response and hypertrophic cellular degeneration in SW 1353 chondrosarcoma cells and is a valuable traditional Chinese medicine for the treatment of knee osteoarthritis.

Engineered MgO nanoparticles for cartilage-bone synergistic therapy

The emerging therapeutic strategies for osteoarthritis (OA) are shifting toward comprehensive approaches that target periarticular tissues, involving both cartilage and subchondral bone. This shift drives the development of single-component therapeutics capable of acting on multiple tissues and cells. Magnesium, an element essential for maintaining skeletal health, shows promise in treating OA. However, the precise effects of magnesium on cartilage and subchondral bone are not yet clear. Here, we investigated the therapeutic effect of Mg2+ on OA, unveiling its protective effects on both cartilage and bone at the cellular and animal levels. The beneficial effect on the cartilage-bone interaction is primarily mediated by the PI3K/AKT pathway. In addition, we developed poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with nano-magnesium oxide modified with stearic acid (SA), MgO&SA@PLGA, for intra-articular injection. These microspheres demonstrated remarkable efficacy in alleviating OA in rat models, highlighting their translational potential in clinical applications.

Microenvironment-responsive bilayer hydrogel microspheres with gelatin-shell for osteoarthritis treatment

Osteoarthritis is a long-term degenerative condition of the joints that is characterized by the breakdown of cartilage and inflammation of the synovial membrane. The presence of an inflammatory microenvironment and the degradation of the extracellular matrix produced by chondrocytes leads to the aggravation of cartilage injury, hindering the treatment of osteoarthritis. A promising approach to address this issue is to apply a combined strategy that is sensitive to the specific conditions in osteoarthritic joints and possesses properties that can reduce inflammation and promote cartilage healing. Here, inspired by the structure of chocolate-covered peanuts, we developed an injectable, environment-responsive bilayer hydrogel microsphere using microfluidics technology. The microsphere applied chondroitin sulfate methacryloyl (ChsMA) as its core and was coated with a methacryloyl gelatin (GelMA) shell that was loaded with celecoxib (CLX) liposomes (ChsMA+CLX@Lipo@GelMA). CLX was released from the liposomes when the GelMA shell rapidly degraded in response to the osteoarthritic microenvironment and suppressed the generation of inflammatory agents, demonstrating a beneficial impact of the outer shell in reducing inflammation. While the inner methacryloyl microsphere core degraded, chondroitin sulfate was released to promote chondrocyte anabolism and facilitate cartilage repair. Thus, the synthesized bilayer hydrogel microspheres hold great potential for treating osteoarthritis.

PPAR γ activation in chondrocytes alleviates glucocorticoid-induced oxidative stress, mitochondrial impairment, and pyroptosis via autophagic flow enhancement

Osteoarthritis (OA) is a progressive age-related disease characterised by pathological changes in the synovium, articular cartilage, and subchondral bone, significantly reducing the patients' quality of life. This study investigated the role of glucocorticoids, specifically dexamethasone, in OA progression, with a particular focus on their effects on chondrocytes. Although glucocorticoids are commonly used for OA pain relief, our research demonstrated that high concentrations of dexamethasone may accelerate OA progression by enhancing the ability of reactive oxygen species to inhibit chondrocyte autophagy, resulting in cell death and accelerated cartilage degeneration. Despite reports on the acceleration of pathogenesis and cartilage damage in some patients of OA taking corticosteroids, the mechanism behind the same has not been investigated. This necessitates an investigation of the concentration-dependent changes in the cartilage cells upon dexamethasone administration. In addition, the protective effect of PPAR γ on chondrocytes can prevent the decrease in chondrocyte autophagy and delay cartilage degeneration. Therefore, our study suggests that the therapeutic use of glucocorticoids in OA treatment should be more nuanced considering their potential detrimental effects. Future investigations should focus on the mechanisms underlying the glucocorticoid-mediated modulation of cell death processes, which could provide insights into new therapeutic strategies for OA treatment.

Standard isometric contraction has higher reliability than maximum voluntary isometric contraction for normalizing electromyography during level walking among older adults with knee osteoarthritis

Introduction: Electromyography (EMG) normalization often relies on maximum voluntary isometric contraction (MVIC), which may not be suitable for knee osteoarthritis (KOA) patients due to difficulties in generating maximum joint torques caused by pain. This study aims to assess the reliability of standard isometric contraction (SIC) for EMG normalization in older adults with KOA, comparing it with MVIC. Methods: We recruited thirty-five older adults with KOA and collected root mean square EMG amplitudes from seven muscles in the affected limb during level walking, SIC, and MVIC tests. EMG data during level walking were normalized using both SIC and MVIC methods. This process was repeated after at least 1 week. We calculated intra-class correlation coefficients (ICCs) with 95% confidence intervals to evaluate between- and within-day reliabilities. Results: SIC tests showed higher between- (ICC: 0.75-0.86) and within-day (ICC: 0.84-0.95) ICCs across all seven muscles compared to MVIC tests. When normalized with SIC, all seven muscles exhibited higher between- (ICC: 0.67-0.85) and within-day (ICC: 0.88-0.99) ICCs compared to MVIC normalization. Conclusion: This study suggests that SIC may offer superior movement consistency and reliability compared to MVIC for EMG normalization during level walking in older adults with KOA.

Clinical Outcome of Multiple Platelet-Rich Plasma Injection and Correlation with PDGF-BB in the Treatment of Knee Osteoarthritis

(1) Background: Current treatments for knee osteoarthritis (KOA), such as intra-articular corticosteroids or hyaluronic acid (HA) injections, are controversial due to their ineffectiveness in preventing disease progression. Platelet-rich plasma (PRP) has become a promising and possible treatment for KOA. It is thought to enhance articular cartilage regeneration and reduce OA-related impairment. PRP contains growth factors such as PDGF-BB, which stimulates growth and inhibits joint damage. Based on numerous studies, after a certain amount of time, it was found that multiple PRP treatments reduced pain more than a single injection. This study evaluates the efficacy of multiple PRP (m-PRP) injections compared to multiple HA (m-HA) injections for KOA treatment, focusing on their correlation with PDGF-BB levels. (2) Methods: In this single-center, open-label, randomized, comparative clinical trial, 30 KOA patients received m-PRP and m-HA injections. VAS and WOMAC were used to evaluate clinical outcomes and PDGF-BB concentrations. (3) Results: The study analysis revealed a statistically significant reduction in pain indices. In both the m-PRP and m-HA groups after 12 weeks, m-PRP showed superior results. PDGF-BB concentrations also increased, with a strong negative correlation and statistical significance using Spearman's rho. (4) Conclusions: Multiple PRP injections are safe and associated with elevated PDGF-BB, reduced VAS and WOMAC scores, providing the potential for articular cartilage regeneration and inhibiting knee osteoarthritis progression.

Downregulation of Gadd45β alleviates osteoarthritis by repressing lipopolysaccharide-induced fibroblast-like synoviocyte inflammation, proliferation and migration

OBJECTIVE

Gadd45β have a regulatory role in cellular inflammation, proliferation and migration. However, the role of Gadd45β in synovial inflammation in osteoarthritis (OA) remains to be explored. This study aimed to ascertain whether Gadd45β is involved in OA synovial inflammation.

METHODS

The rat model was induced by sodium iodoacetate and the cellular model was constructed with lipopolysaccharide (LPS)-induced fibroblast-like synoviocytes (FLSs). siRNA was applied to interfere with the expression of intracellular Gadd45β. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to detect the expression of Gadd45β mRNA and protein. The inflammation, proliferation, and migration of OA-FLSs were detected by enzyme-linked immunosorbent assay, cell scratch assay, 5-ethynyl-2'-deoxyuridine assay, etc. The effect of downregulation of Gadd45β on the nuclear factor-κB (NF-κB) pathway was investigated.

RESULTS

Expression of Gadd45β in OA rat synovial tissues and OA-FLSs was increased, and LPS treatment promoted cell proliferation and enhanced cell migration. Gadd45β interference inhibited the inflammation, proliferation and migration of cells induced by LPS. LPS promoted P65 expression in the nucleus and activated the NF-κB signaling pathway, whereas si-Gadd45β reversed this situation.

CONCLUSIONS

si-Gadd45β inhibited the inflammatory response, proliferation and migration of FLSs, and activation of the NF-κB signaling pathway, which could delay the progression of OA. Hence, it may become a potential therapeutic target for OA.

Pathogenic Mechanisms and Therapeutic Approaches in Obesity-Related Knee Osteoarthritis

The knee is the joint most frequently involved in osteoarthritis, a common joint disorder in the adult population that is associated with significant chronic joint pain, reduced mobility and quality of life. Recent studies have established an association between obesity and the development of knee osteoarthritis that goes beyond the increased mechanical load on the knees as weight-bearing joints. This link is based on the maintenance of a chronic low-grade inflammation, altered secretion of adipokines by the adipose tissue and development of sarcopenia. Major adipokines involved in the pathogenesis of obesity-related knee osteoarthritis include adiponectin, which appears to have a protective effect, as well as leptin, resistin and visfatin, which are associated with higher pain scores and more severe structural damage. Joint pain in knee osteoarthritis may be both nociceptive and neuropathic and is the result of complex mechanisms driven by nerve growth factor, calcitonin gene-related peptide and pro-inflammatory cytokines. The role of endogenous cannabinoids and gut microbiota in common mechanisms between obesity and knee pain has recently been studied. The aim of the present review is to highlight major pathogenic mechanisms in obesity-related knee osteoarthritis with special attention on pain and to comment on possible therapeutic approaches.

Classification of distinct osteoarthritis subtypes with different knee joint tissues by gene expression profiles

Aims

Knee osteoarthritis (OA) involves a variety of tissues in the joint. Gene expression profiles in different tissues are of great importance in order to understand OA.

Methods

First, we obtained gene expression profiles of cartilage, synovium, subchondral bone, and meniscus from the Gene Expression Omnibus (GEO). Several datasets were standardized by merging and removing batch effects. Then, we used unsupervised clustering to divide OA into three subtypes. The gene ontology and pathway enrichment of three subtypes were analyzed. CIBERSORT was used to evaluate the infiltration of immune cells in different subtypes. Finally, OA-related genes were obtained from the Molecular Signatures Database for validation, and diagnostic markers were screened according to clinical characteristics. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to verify the effectiveness of markers.

Results

C1 subtype is mainly concentrated in the development of skeletal muscle organs, C2 lies in metabolic process and immune response, and C3 in pyroptosis and cell death process. Therefore, we divided OA into three subtypes: bone remodelling subtype (C1), immune metabolism subtype (C2), and cartilage degradation subtype (C3). The number of macrophage M0 and activated mast cells of C2 subtype was significantly higher than those of the other two subtypes. COL2A1 has significant differences in different subtypes. The expression of COL2A1 is related to age, and trafficking protein particle complex subunit 2 is related to the sex of OA patients.

Conclusion

This study linked different tissues with gene expression profiles, revealing different molecular subtypes of patients with knee OA. The relationship between clinical characteristics and OA-related genes was also studied, which provides a new concept for the diagnosis and treatment of OA.

Integrating multiple microarray datasets to explore the significance of ferroptosis regulators in the diagnosis and subtype classification of osteoarthritis

Osteoarthritis (OA) is a chronic joint disease that reduces quality of life for patients. Ferroptosis plays a significant role in OA. However, its underlying mechanism remains unclear. In this study, we integrated 7 OA synovial datasets from the GEO database to screen for significant ferroptosis-related genes. The top 5 ferroptosis regulators were used to construct nomogram models to predict OA prevalence. Consensus clustering was applied to classify OA patients into different ferroptosis patterns based on significant ferroptosis-related genes. Subsequently, an immune cell infiltration study was performed to investigate the relationship between the significant ferroptosis regulators and immune cells. As a result, we screened 11 ferroptosis-related genes in OA patients. Five candidate ferroptosis regulators (SLC7A11, ALOX5, SLC1A5, GOT1, and GSS) were used to predict OA risk. The nomogram model based on these 5 genes is important for assessing the occurrence of OA. Consensus clustering analysis showed that OA patients could be classified into 2 ferroptosis patterns (Clusters A and B). Immune cell infiltration levels were higher in Cluster B than in Cluster A. Two subtypes, gene Clusters A and B, were classified according to the expression of ferroptosis-related DEGs among the ferroptosis patterns. Cluster A and gene Cluster A had higher ferroptosis scores than Cluster B or gene Cluster B, whereas the expression levels of the proinflammatory cytokines interleukin (IL)-1β, tumor necrosis factor, IL-6, IL-18, and IL-10 were higher in Cluster B or gene Cluster B than those in Cluster A or gene Cluster A. Different subtypes of ferroptosis play critical roles in OA. Furthermore, immunotherapy strategies for OA treatment may be guided by our study on ferroptosis patterns.

MicroRNA expression in osteoarthritis: a meta-analysis

Osteoarthritis (OA) is one of the most prevalent musculoskeletal diseases globally, leading to chronic disability and poor prognosis. One of the approaches for optimizing OA treatment is to find early effective diagnostic biomarkers. The contribution of microRNAs (miRNAs) in OA progression is now being increasingly recognized. This review provides a comprehensive summary on studies reporting the expression profiling of miRNAs in OA and associated signaling pathways. We performed a systematic search of the Embase, Web of Science, PubMed, and Cochrane library databases. This systematic review is reported according to the PRISMA checklist. Studies which identified miRNAs with aberrant expression compared to controls during OA progression were included, and a meta-analysis was performed. Results from the random effects model were provided as log10 odds ratios (logORs) and 95% confidence intervals. Sensitivity analysis was conducted to confirm the accuracy of the results. Subgroup analysis was conducted based on tissue source. The target genes of miRNAs identified in this study were extracted from the MiRWalk database, and these target genes were enriched in Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways. A total of 191 studies reporting 162 miRNAs were included in our meta-analysis. Among them, 36 miRNAs distributed across 96 studies were expressed in the same direction in at least two studies (13 up-regulated and 23 down-regulated). Subgroup analysis of tissue source revealed that the highest number of studies was conducted using articular cartilage, where the most up-regulated miRNAs were miR-146a-5p (logOR 7.355; P < 0.001) and miR-34a-5p (logOR 6.955; P < 0.001), and the most down-regulated miRNAs were miR-127-5p (logOR 6.586; P < 0.001) and miR-140-5p (logOR 6.373; P < 0.001). Enrichment analysis of 752 downstream target genes of all identified miRNAs was performed, and the regulatory relationships among them were displayed. Mesenchymal stem cells and transforming growth factor-β were found to be the most important downstream effectors regulated by miRNA in OA. This study highlighted the importance of miRNA signaling in OA progression and identified a number of prominent miRNAs including miR-146a-5p, miR-34a-5p, miR-127-5p, and miR-140-5p which might be considered as potential biomarkers for OA.

Disease-modifying agents in osteoarthritis: where are we now and what does the future hold?

Cite this article: Bone Joint Res  2023;12(10):654–656.

A Bidirectional Mendelian Randomization Study of Sarcopenia-Related Traits and Knee Osteoarthritis

Background

With the development of population aging worldwide, sarcopenia and knee osteoarthritis (KOA), two age-related diseases, will continue to impose increasing medical and economic burdens on the society. Previous studies have discovered an association between the two, but the causality remains controversial, and it is difficult to eliminate confounding factors. Therefore, a Mendelian randomization (MR) study was conducted to overcome these confounding factors and investigate the causal relationship between sarcopenia and KOA.

Objective

The present work focused on assessing the causality between KOA and sarcopenia, so as to provide new strategies to prevent and treat these two conditions in clinic.

Methods

We registered the title with PROSPERO (ID: CRD42023421096). The two-sample bidirectional MR analysis was conducted in two steps, with sarcopenia being the exposure whereas KOA being the outcome in the first step, and vice versa in the second step. Genome-wide association studies (GWAS) data on low hand-grip strength (n=256,523), walking pace (n=459,915), appendicular lean mass (ALM, n=450,243), and KOA (n=403,124) were obtained from the UK Biobank. Methods such as the inverse variance weighted (IVW) and weighted median were utilized for assessing the causality of KOA with sarcopenia, and sensitivity analyses were also conducted.

Results

In the main MR analysis using the IVW method, evidence suggested that low hand-grip strength, walking pace, and ALM had adverse effects on KOA (p-value 0.0001, odds ratio (OR) 1.4569, 95% confidence interval (CI) 1.2007-1.7677 for low hand-grip strength; p-value 0.0003, OR 1.1500, 95% CI 1.050-1.183 for ALM; p-value 5.29E-19, OR 0.0932, 95% CI 0.0553-0.1572 for walking pace). However, there was no causality of KOA with sarcopenia in the opposite direction.

Conclusion

Our study suggests an obvious unidirectional causality of KOA with sarcopenia, and supports the notion that patients with sarcopenia are more susceptible to the development of KOA.

Mesenchymal stem cells influence monocyte/macrophage phenotype: Regulatory mode and potential clinical applications

Mesenchymal stem cells (MSCs) are pluripotent stem cells derived from a variety of tissues, such as umbilical cord, fat, and bone marrow. Today, MSCs are widely recognized for their prominent anti-inflammatory properties in a variety of acute and chronic inflammatory diseases. In inflammatory diseases, monocytes/macrophages are an important part of the innate immune response in the body, and the alteration of the inflammatory phenotype plays a crucial role in the secretion of pro-inflammatory/anti-inflammatory factors, the repair of injured sites, and the infiltration of inflammatory cells. In this review, starting from the effect of MSCs on the monocyte/macrophage phenotype, we have outlined in detail the process by which MSCs influence the transformation of the monocyte/macrophage inflammatory phenotype, emphasizing the central role of monocytes/macrophages in MSC-mediated anti-inflammatory and damage site repair. MSCs are phagocytosed by monocytes/macrophages in various physiological states, the paracrine effect of MSCs and mitochondrial transfer of MSCs to macrophages to promote the transformation of monocytes/macrophages into anti-inflammatory phenotypes. We also review the clinical applications of the MSCs-monocytes/macrophages system and describe novel pathways between MSCs and tissue repair, the effects of MSCs on the adaptive immune system, and the effects of energy metabolism levels on monocyte/macrophage phenotypic changes.

Comparison of joint awareness after total knee arthroplasty, medial unicompartmental knee arthroplasty, and high tibial osteotomy: a retrospective study

INTRODUCTION

This study aimed to compare the Forgotten Joint Score-12(FJS) outcomes and the minimum clinically important difference (MCID) of the FJS after high tibial osteotomy (HTO), unicompartmental knee arthroplasty (UKA), and total knee arthroplasty (TKA) with short-term follow-up (at least 2 years). Another objective of the study is to investigate the factors influencing FJS. It is hypothesized that there are differences in FJS outcomes among the three procedures.

METHODS

Patients who underwent HTO, UKA, and TKA from January 2016 to December 2020 and were followed up for a minimum of 2 years were included in the study. The FJS were analyses from a cohort of people who submitted data to two years. The preoperative and postoperative clinical outcomes were compared and evaluated the patient-related factor. The FJS scores were predicted using multiple linear regression analysis. Additionally, Patient's Joint Perception (PJP) questions were used as anchors to determine the achievement of the forgotten joint, and FJS MCID were calculated using the receiver operating characteristic curve (ROC).

RESULTS

Three hundred eighty-nine patients were included in the final study, and there were 111 patients in HTO groups,128patients in UKA groups, and 150 patients in TKA groups. The mean follow-up was 47.0 months. There was a significant difference in the total FJS, between the HTO, UKA, and TKA groups (FJS:59.38 ± 7.25, 66.69 ± 7.44 and 56.90 ± 6.85, p < 0.001. We found the MCID of the FJS of HTO, UKA, and TKA were 63.54, 69.79, and 61.45, respectively. In multiple linear regression, younger age, and higher FS were significant predictors of better FJS.

CONCLUSION

Medial UKA demonstrated lower patient awareness in comparison to HTO and TKA, as assessed by the FJS. Younger age and higher FS were identified as significant predictors of improved FJS, providing valuable guidance for surgical decision-making.

Expression patterns of eight RNA-modified regulators correlating with immune infiltrates during the progression of osteoarthritis

Background

RNA modifications in eukaryotic cells have emerged as an exciting but under-explored area in recent years and are considered to be associated with many human diseases. While several studies have been published relating to m6A in osteoarthritis (OA), we only have limited knowledge of other kinds of RNA modifications. Our study investigated eight RNA modifiers' specific roles in OA including A-to-I, APA, m5C, m6A, m7G, mcm5s2U, Nm and Ψ together with their relationship with immune infiltration.

Methods

RNA modification patterns in OA samples were identified based on eight-type RNA modifiers and their correlation with the degree of immune infiltration was also methodically investigated. Receiver operating characteristic curves (ROC) and qRT-PCR was performed to confirm the abnormal expression of hub genes. The RNA modification score (Rmscore) was generated by the applications of principal component analysis (PCA) algorithm in order to quantify RNA modification modes in individual OA patients.

Results

We identified 21 differentially-expressed RNA modification related genes between OA and healthy samples. For example, CFI, CBLL1 and ALKBH8 were expressed at high levels in OA (P<0.001), while RPUSD4, PUS1, NUDT21, FBL and WDR4 were expressed at low levels (P<0.001). Two candidate RNA modification regulators (WDR4 and CFI) were screened out utilizing a random forest machine learning model. We then identified two distinctive RNA modification modes in OA which were found to display distinctive biological features. High Rmscore, characterized by increased immune cell infiltration, indicated an inflamed phenotype.

Conclusions

Our study was the first to systematically reveal the crosstalk and dysregulations eight-type of RNA modifications in OA. Assessing individuals' RNA modification patterns will be conductive to enhance our understanding of the properties of immune infiltration, provide novel diagnostic and prognostic biomarkers, and guide more effective immunotherapy strategies in the future.

Machine learning identification of thresholds to discriminate osteoarthritis and rheumatoid arthritis synovial inflammation

BACKGROUND

We sought to identify features that distinguish osteoarthritis (OA) and rheumatoid arthritis (RA) hematoxylin and eosin (H&E)-stained synovial tissue samples.

METHODS

We compared fourteen pathologist-scored histology features and computer vision-quantified cell density (147 OA and 60 RA patients) in H&E-stained synovial tissue samples from total knee replacement (TKR) explants. A random forest model was trained using disease state (OA vs RA) as a classifier and histology features and/or computer vision-quantified cell density as inputs.

RESULTS

Synovium from OA patients had increased mast cells and fibrosis (p < 0.001), while synovium from RA patients exhibited increased lymphocytic inflammation, lining hyperplasia, neutrophils, detritus, plasma cells, binucleate plasma cells, sub-lining giant cells, fibrin (all p < 0.001), Russell bodies (p = 0.019), and synovial lining giant cells (p = 0.003). Fourteen pathologist-scored features allowed for discrimination between OA and RA, producing a micro-averaged area under the receiver operating curve (micro-AUC) of 0.85±0.06. This discriminatory ability was comparable to that of computer vision cell density alone (micro-AUC = 0.87±0.04). Combining the pathologist scores with the cell density metric improved the discriminatory power of the model (micro-AUC = 0.92±0.06). The optimal cell density threshold to distinguish OA from RA synovium was 3400 cells/mm2, which yielded a sensitivity of 0.82 and specificity of 0.82.

CONCLUSIONS

H&E-stained images of TKR explant synovium can be correctly classified as OA or RA in 82% of samples. Cell density greater than 3400 cells/mm2 and the presence of mast cells and fibrosis are the most important features for making this distinction.

Analgesic Effectiveness of Physical Therapy Combining the Use of Electromagnetic Fields with Light Radiation Emitted by LEDs along with the Use of Topical Herbal Ointment in Patients with Gonarthrosis

(1) Background: The aim of the study is to evaluate the analgesic effectiveness of a physical therapy regimen that combines the use of an electromagnetic field with light radiation emitted by LEDs, along with the use of Traumeel S ointment, in patients with gonarthrosis. (2) Methods: The study included 90 patients with knee osteoarthritis (grade 2 Kellgren and Lawrence osteoarthritis). They were divided into three groups: Group I, 30 patients treated with magnetic stimulation plus LED therapy; Group II, 30 patients treated with Traumeel S ointment; and Group III, 30 patients treated with magnetic stimulation plus LED therapy with Traumeel S ointment. Pain intensity was assessed using the VAS and Laitinen scales before and after a series of treatments. (3) Results: Significant results in terms of pain reduction before and after treatment were obtained in each of the study groups, as there were significant differences in the VAS pain intensity scores before and after the procedures between the groups. In group I, with electromagnetic field and LED light treatment, the difference was 35.5; in group II, which received Traumeel S® ointment, the difference was 18.5; and in group III, with electromagnetic field and LED light treatment as well as Traumeel S ointment, the difference was 26.5. In the Laitinen scale, the differences were insignificant, although the size distribution was similar. (4) Conclusions: The therapy used in this study showed that magnetic stimulation plus LED therapy and the use of Traumeel S ointment gave positive results in terms of pain reduction in each of the study groups. The strongest analgesic factor seems to be magnetic and LED therapies used separately. Traumeel S in magnetoledophoresis does not work synergistically with the magnetic field of LED light, and even worsens the effect of the therapy used.

Identification and validation of BCL6 and VEGFA as biomarkers and ageing patterns correlating with immune infiltrates in OA progression

Osteoarthritis (OA), the most common type of arthritis, is a complex biological response caused by cartilage wear and synovial inflammation that links biomechanics and inflammation. The progression of OA correlates with a rise in the number of senescent cells in multiple joint tissues. However, the mechanisms by which senescent cells and their involvement with immune infiltration promote OA progression are not fully understood. The gene expression profiles and clinical information of OA and healthy control synovial tissue samples were retrieved from the Gene Expression Omnibus database, and then differential analysis of senescence regulators between OA and normal samples was performed. The random forest (RF) was used to screen candidate senescence regulators to predict the occurrence of OA. The reverse transcription quantitative real-time PCR experiments at tissue's level was performed to confirm these biomarkers. Moreover, two distinct senescence patterns were identified and systematic correlation between these senescence patterns and immune cell infiltration was analyzed. The senescence score and senescence gene clusters were constructed to quantify senescence patterns together with immune infiltration of individual OA patient. 73 senescence differentially expressed genes were identified between OA patients and normal controls. The RF method was utilized to build an OA risk model based on two senescence related genes: BCL6 and VEGFA. Next, two distinct aging patterns were determined in OA synovial samples. Most patients from senescence cluster A were further classified into gene cluster B and high senescence score group correlated with a non-inflamed phenotype, whereas senescence cluster B were classified into gene cluster A and low senescence score group correlated with an inflamed phenotype. Our study revealed that senescence played an important role in in OA synovial inflammation. Evaluating the senescence patterns of individuals with OA will contribute to enhancing our cognition of immune infiltration characterization, providing novel diagnostic and prognostic biomarkers, and guiding more effective immunotherapy strategies.

Effects of Immobilization and Swimming on the Progression of Osteoarthritis in Mice

Osteoarthritis (OA) is a chronic joint disease characterized by the degeneration of articular cartilage and thickening and sclerosis of the subchondral bone. Mechanical factors play significant roles in the development and progression of OA, but it is still controversial whether exercise or rest is a more effective treatment for OA patients. In this study, we compared the effects of swimming and immobilization at different stages of OA in mice. Four weeks (the middle stage of OA) or eight weeks (the late stage of OA) after DMM (destabilization of the medial meniscus) surgery, the mice were subjected to four-week immobilization or swimming. Ink blot analysis and a beam walking test were performed to measure the gait and balance ability. Histological analysis was performed to determine the trabecular bone area, the thickness of subchondral bone, the thickness of the cartilage, the OARSI score, and the expression of MMP13 (matrix metalloproteinases) and IL-6 (interleukin). The results showed that at the middle stage of OA, both immobilization and swimming slowed down the progression of OA. Immobilization relieved OA to a certain extent by decreasing the production of regulatory factors to attenuate the degeneration of cartilage, which partly relieved the effects of DMM on gait, mainly in the hindlimb. Swimming mainly attenuated the thickening and rescued the area of subchondral bone.

Osteoarthritis as an Umbrella Term for Different Subsets of Humans Undergoing Joint Degeneration: The Need to Address the Differences to Develop Effective Conservative Treatments and Prevention Strategies

Osteoarthritis (OA) of joints such as the knee and hip are very prevalent, and the number of individuals affected is expected to continue to rise. Currently, conservative treatments after OA diagnosis consist of a series of increasingly invasive interventions as the degeneration and pain increase, leading very often to joint replacement surgery. Most interventions are focused on alleviating pain, and there are no interventions currently available that stop and reverse OA-associated joint damage. For many decades OA was considered a disease of cartilage, but it is now considered a disease of the whole multi-tissue joint. As pain is the usual presenting symptom, for most patients, it is not known when the disease process was initiated and what the basis was for the initiation. The exception is post-traumatic OA which results from an overt injury to the joint that elevates the risk for OA development. This scenario leads to very long wait lists for joint replacement surgery in many jurisdictions. One aspect of why progress has been so slow in addressing the needs of patients is that OA has been used as an umbrella term that does not recognize that joint degeneration may arise from a variety of mechanistic causes that likely need separate analysis to identify interventions unique to each subtype (post-traumatic, metabolic, post-menopausal, growth and maturation associated). A second aspect of the slow pace of progress is that the bulk of research in the area is focused on post-traumatic OA (PTOA) in preclinical models that likely are not clearly relevant to human OA. That is, only ~12% of human OA is due to PTOA, but the bulk of studies investigate PTOA in rodents. Thus, much of the research community is failing the patient population affected by OA. A third aspect is that conservative treatment platforms are not specific to each OA subset, nor are they integrated into a coherent fashion for most patients. This review will discuss the literature relevant to the issues mentioned above and propose some of the directions that will be required going forward to enhance the impact of the research enterprise to affect patient outcomes.

Melatonin: A novel candidate for the treatment of osteoarthritis

Osteoarthritis (OA), characterized by cartilage erosion, synovium inflammation, and subchondral bone remodeling, is a common joint degenerative disease worldwide. OA pathogenesis is regulated by multiple predisposing factors, including imbalanced matrix metabolism, aberrant inflammatory response, and excessive oxidative stress. Moreover, melatonin has been implicated in development of several degenerative disorders owing to its potent biological functions. With regards to OA, melatonin reportedly promotes synthesis of cartilage matrix, inhibition of chondrocyte apoptosis, attenuation of inflammatory response, and suppression of matrix degradation by regulating the TGF-β, MAPK, or NF-κB signaling pathways. Notably, melatonin has been associated with amelioration of oxidative damage by restoring the OA-impaired intracellular antioxidant defense system in articular cartilage. Findings from preliminary application of melatonin or melatonin-loaded biomaterials in animal models have affirmed its potential anti-arthritic effects. Herein, we summarize the anti-arthritic effects of melatonin on OA cartilage and demonstrate that melatonin has potential therapeutic efficacy in treating OA.