Early knee OA definition-what do we know at this stage? An imaging perspective

Transformative approaches for effective clinical trials to reduce the disease burden of osteoarthritis

Osteoarthritis (OA) is a leading cause of disability and morbidity that has eluded development of effective disease modifying drugs and therapies. While established OA in the form of symptomatic radiographic disease is a recognizable final common pathway, OA development encompasses a broad spectrum of pathological changes, susceptibilities, and etiological pathways that cannot be considered a single disease process. Beginning with preclinical disease where radiographs are normal, the concept of pre-osteoarthritis (pre-OA) offers a systems-based approach to OA prevention by targeting reduction of OA risk prior to the onset of definable OA. Early OA ensues when cellular, molecular, and joint tissue changes begin to overlap that of OA, a process that can begin before the onset of definitive symptoms or radiographic changes. A myriad of pathways and crossroads of pre-OA and early OA eventually leads to poorly irreversible symptomatic radiographic OA. With increasing recognition of pre-OA and early OA markers, pathways and subtypes, opportunities arise to address these new therapeutic targets. The current status of clinical trials in OA was identified as a critical barrier to progress by the 2022 National Institute of Arthritis, Musculoskeletal, and Skin Diseases (NIAMS) Roundtable on "Cartilage Preservation and Restoration in Knee Osteoarthritis: Challenges, Gaps, and Opportunities". This manuscript summarizes the recommendations of the work group established from the Roundtable to address this issue. The work group recommends that clinical trial design and endpoints evolve to effectively evaluate new treatment approaches suitable for pre-osteoarthritis and early OA by different criteria than what has been set for symptomatic radiographic OA. While symptomatic improvement is the primary goal for palliation of irreversible established OA, important goals for treating earlier disease states include disease modification and prevention, with the potential to alter the natural history of progressive OA. Because symptoms may not correlate with structural changes in pre-OA and early OA, the primary outcomes in these trials need to match the intended mechanistic target and the therapeutic goal for the disease state being treated. The purpose of this manuscript is to transform the approach to clinical trials in OA by establishing a new benchmark of identifying critical outcomes that are appropriate for the joint disease states and subtypes of the target patient population, and the therapeutic or mechanistic target of the intervention being tested. By shifting the approach from using standardized outcomes based on established OA towards customizing clinical trials according to these principles, new precision medicine strategies to address the full spectrum of disease from pre-OA to OA can be more readily advanced into clinical practice.

MicroRNA signature for early prediction of knee osteoarthritis structural progression using integrated machine and deep learning approaches

OBJECTIVE

Conventional methodologies are ineffective in predicting the rapid progression of knee osteoarthritis (OA). MicroRNAs (miRNAs) show promise as biomarkers for patient stratification. We aimed to develop a miRNA prognosis model for identifying knee OA structural progressors/non-progressors using integrated machine/deep learning tools.

METHODS

Baseline serum miRNAs from Osteoarthritis Initiative (OAI) participants were isolated and sequenced. Participants were categorized based on their likelihood of knee structural progression/non-progression using magnetic resonance imaging and X-ray data. For prediction model development, 152 OAI participants (91 progressors, 61 non-progressors) were used. MiRNA features were reduced through VarClusHi clustering. Key miRNAs and OA determinants (age, sex, body mass index, race) were identified using seven machine learning tools. The final prediction model was developed using advanced machine/deep learning techniques. Model performance was assessed with area under the curve (AUC) (95% confidence intervals) and accuracy. Monte Carlo cross-validation ensured robustness. Model validation used 30 OAI baseline plasma samples from an independent set of participants (14 progressors, 16 non-progressors).

RESULTS

Feature clustering selected 107 miRNAs. Elastic Net was chosen for feature selection. An optimized prediction model based on an Artificial Neural Network comprising age and four miRNAs (hsa-miR-556-3p, hsa-miR-3157-5p, hsa-miR-200a-5p, hsa-miR-141-3p) exhibited excellent performance (AUC, 0.94 [0.89, 0.97]; accuracy, 0.84 [0.77, 0.89]). Model validation performance (AUC, 0.81 [0.63, 0.92]; accuracy, 0.83 [0.66, 0.93]) demonstrated the potential for generalization.

CONCLUSION

This study introduces a novel miRNA prognosis model for knee OA patients at risk of structural progression. It requires five baseline features, demonstrates excellent performance, is validated with an independent set, and holds promise for future personalized therapeutic monitoring.

Medial degenerative disease of the knee without radiographic osteoarthritis is a good indication for medial open wedge high tibial osteotomy

INTRODUCTION

Medial open wedge high tibial osteotomy (MOWHTO) is a well-established surgical procedure for osteoarthritis (OA) of the knee with varus malalignment. However, it is uncertain whether MOWHTO is an effective surgical procedure for early OA. This study aimed to evaluate the clinical results of MOWHTO for early OA of the knee with varus malalignment.

MATERIALS AND METHODS

This was a retrospective analysis of 87 patients in whom varus malalignment was corrected by MOWHTO between January 2017 and December 2022. Kellgren-Lawrence grade 0-1 was defined as early OA and grade ≥ 2 as established OA. Range of motion at the knee, Forgotten Joint Score-12, Knee Injury and Osteoarthritis Outcome Score, and radiological findings were compared between the early OA group and the established OA group.

RESULTS

The established OA group (n = 49) was significantly older than the early OA group (n = 38) (p = 0.02). There were no differences between the groups in preoperative or postoperative hip-knee-ankle angle or range of motion or in improvements in the Forgotten Joint Score-12 or Knee Injury and Osteoarthritis Outcome Score. The median follow-up duration was more than 24.0 months in both groups.

CONCLUSION

MOWHTO had a good clinical outcome in patients with early OA and varus malalignment over a median follow-up of 2 years.

LEVEL OF EVIDENCE

III, retrospective study.

EUROVISCO Consensus Guidelines for the Use of Hyaluronic Acid Viscosupplementation in Knee Osteoarthritis Based on Patient Characteristics

OBJECTIVES

Viscosupplementation with hyaluronic acid (HA) is a commonly used intra-articular treatment for osteoarthritis (OA). We performed a Delphi consensus process to formulate guidelines for the use of intra-articular hyaluronic acid (IAHA) knee injection according to the patient's characteristics.

METHODS

The EUROVISCO group consists of 12 members who had expertise in clinical and/or research in the field of OA and IAHA treatment. This group drafted issues through an iterative process and subsequently voted according to a Delphi process on their level of agreement (LoA) on these recommendations. The scores were pooled to generate a median agreement score for each recommendation. The strength of the recommendation (SOR) was classified as strong if the median agreement score was ≥8. The level of consensus (LOC) was also obtained. The level of evidence was given for each recommendation.

RESULTS

A total of 34 statements were evaluated by the expert group. A unanimous or high LoA was obtained in 16. IAHA can be considered irrespective of the age in patients with symptomatic knee OA. It can be used in patients with diabetes and/or moderate to severe obesity. It can also be used in knee OA patients with a history of gout, meniscocalcinosis and with mild-to-moderate varus/valgus malalignment. The group recommended against the use of VS in pregnant women and in OA flare.

CONCLUSION

In summary, the working group provided strong recommendations for the use of IAHA injection that will facilitate individualized treatment decision algorithms in the management of knee OA.

Serum lncRNA ITGB2-AS1 and ICAM-1 as novel biomarkers for rheumatoid arthritis and osteoarthritis diagnosis

BACKGROUND

The complete circulating long non-coding RNAs (lncRNAs) signature of rheumatoid arthritis (RA) and osteoarthritis (OA) is still uncovered. The lncRNA integrin subunit beta 2 (ITGB2)-anti-sense RNA 1 (ITGB2-AS1) affects ITGB2 expression; however, there is a gap in knowledge regarding its expression and clinical usefulness in RA and OA. This study investigated the potential of serum ITGB2-AS1 as a novel diagnostic biomarker and its correlation with ITGB2 expression and its ligand intercellular adhesion molecule-1 (ICAM-1), disease activity, and severity in RA and primary knee OA patients.

SUBJECTS

Forty-three RA patients, 35 knee OA patients, and 22 healthy volunteers were included.

RESULTS

Compared with healthy controls, serum ITGB2-AS1 expression was upregulated in RA patients but wasn't significantly altered in knee OA patients, whereas serum ICAM-1 protein levels were elevated in both diseases. ITGB2-AS1 showed discriminative potential for RA versus controls (AUC = 0.772), while ICAM-1 displayed diagnostic potential for both RA and knee OA versus controls (AUC = 0.804, 0.914, respectively) in receiver-operating characteristic analysis. In the multivariate analysis, serum ITGB2-AS1 and ICAM-1 were associated with the risk of developing RA, while only ICAM-1 was associated with the risk of developing knee OA. A panel combining ITGB2-AS1 and ICAM-1 showed profound diagnostic power for RA (AUC = 0.9, sensitivity = 86.05%, and specificity = 91.67%). Interestingly, serum ITGB2-AS1 positively correlated with disease activity (DAS28) in RA patients and with ITGB2 mRNA expression in both diseases, while ICAM-1 positively correlated with ITGB2 expression in knee OA patients.

CONCLUSION

Our study portrays serum ITGB2-AS1 as a novel potential diagnostic biomarker of RA that correlates with disease activity. A predictive panel combining ITGB2-AS1 and ICAM-1 could have clinical utility in RA diagnosis. We also spotlight the association of ICAM-1 with knee OA diagnosis. The correlation of serum ITGB2-AS1 with ITGB2 expression in both diseases may be insightful for further mechanistic studies.

Planned or recent first consultation with the general practitioner for knee complaints: Is it indicative of early-stage knee osteoarthritis?

Objective

No established definition for early-stage knee osteoarthritis (KOA) is available, nor classification criteria. Identifying the characteristics of individuals presenting with early-stage KOA symptoms can enhance diagnosis to prevent progression. This study aimed to describe clinical and structural features of individuals presenting with knee complaints within two years after their first consultation, while exploring differences in the duration of knee complaints.

Method

Baseline data was used from the LITE randomized controlled trial, assessing the effectiveness of a lifestyle intervention for individuals with knee complaints and overweight in primary care. Baseline assessments included questionnaires, clinical assessment, and MRI of the most symptomatic knee. Differences between groups with varying durations of knee complaints (<12, ≥12-<24, ≥24 months) were evaluated.

Results

Participants (N ​= ​218, 65% female, mean age 59 ​± ​6 years, mean BMI 32 ​± ​5 ​kg/m2) had a median knee complaint duration of 14 months, with an average KOOS pain score of 60 ​± ​17.46% reported their symptoms as unacceptable. Structural MRI-defined KOA was observed in 71% of participants. There were no significant differences in clinical or structural MRI features between different durations of knee complaints.

Conclusion

Within 24 months of initial consultation, over two-thirds of participants displayed MRI-defined structural KOA, and nearly half reported unacceptable symptom states. This study found no association between the duration of knee complaints and symptoms severity or structural KOA presence, underscoring the complexity of identifying stages of KOA among individuals with overweight. Future studies should explore additional features beyond current considerations to facilitate early-stage KOA diagnosis, specifically for individuals with overweight.

Osteoclasts and osteoarthritis: Novel intervention targets and therapeutic potentials during aging

Osteoarthritis (OA), a chronic degenerative joint disease, is highly prevalent among the aging population, and often leads to joint pain, disability, and a diminished quality of life. Although considerable research has been conducted, the precise molecular mechanisms propelling OA pathogenesis continue to be elusive, thereby impeding the development of effective therapeutics. Notably, recent studies have revealed subchondral bone lesions precede cartilage degeneration in the early stage of OA. This development is marked by escalated osteoclast-mediated bone resorption, subsequent imbalances in bone metabolism, accelerated bone turnover, and a decrease in bone volume, thereby contributing significantly to the pathological changes. While the role of aging hallmarks in OA has been extensively elucidated from the perspective of chondrocytes, their connection with osteoclasts is not yet fully understood. There is compelling evidence to suggest that age-related abnormalities such as epigenetic alterations, proteostasis network disruption, cellular senescence, and mitochondrial dysfunction, can stimulate osteoclast activity. This review intends to systematically discuss how aging hallmarks contribute to OA pathogenesis, placing particular emphasis on the age-induced shifts in osteoclast activity. It also aims to stimulate future studies probing into the pathological mechanisms and therapeutic approaches targeting osteoclasts in OA during aging.

[Identification of Osteoarthritis Inflamm-Aging Biomarkers by Integrating Bioinformatic Analysis and Machine Learning Strategies and the Clinical Validation]

Objective

To identify inflamm-aging related biomarkers in osteoarthritis (OA).

Methods

Microarray gene profiles of young and aging OA patients were obtained from the Gene Expression Omnibus (GEO) database and aging-related genes (ARGs) were obtained from the Human Aging Genome Resource (HAGR) database. The differentially expressed genes of young OA and older OA patients were screened and then intersected with ARGs to obtain the aging-related genes of OA. Enrichment analysis was performed to reveal the potential mechanisms of aging-related markers in OA. Three machine learning methods were used to identify core senescence markers of OA and the receiver operating characteristic (ROC) curve was used to assess their diagnostic performance. Peripheral blood mononuclear cells were collected from clinical OA patients to verify the expression of senescence-associated secretory phenotype (SASP) factors and senescence markers.

Results

A total of 45 senescence-related markers were obtained, which were mainly involved in the regulation of cellular senescence, the cell cycle, inflammatory response, etc. Through the screening with the three machine learning methods, 5 core senescence biomarkers, including FOXO3, MCL1, SIRT3, STAG1, and S100A13, were obtained. A total of 20 cases of normal controls and 40 cases of OA patients, including 20 cases in the young patient group and 20 in the elderly patient group, were enrolled. Compared with those of the young patient group, C-reactive protein (CRP), interleukin (IL)-6, and IL-1β levels increased and IL-4 levels decreased in the elderly OA patient group (P<0.01); FOXO3, MCL1, and SIRT3 mRNA expression decreased and STAG1 and S100A13 mRNA expression increased (P<0.01). Pearson correlation analysis demonstrated that the selected markers were associated with some indicators, including erythrocyte sedimentation rate (ESR), IL-1β, IL-4, CRP, and IL-6. The area under the ROC curve of the 5 core aging genes was always greater than 0.8 and the C-index of the calibration curve in the nomogram prediction model was 0.755, which suggested the good calibration ability of the model.

Conclusion

FOXO3, MCL1, SIRT3, STAG1, and S100A13 may serve as novel diagnostic biomolecular markers and potential therapeutic targets for OA inflamm-aging.

Quantification of Synovial Fluid Using Magnetic Resonance Fingerprinting Multicomponent Imaging in the Articular Cartilage of the Knee

RATIONALE AND OBJECTIVES

The purpose of this study was to verify the feasibility of magnetic resonance fingerprinting (MRF)-derived synovial fluid fraction (SFF) mapping for quantifying subvoxel-sized cartilage defects.

MATERIALS AND METHODS

MRF was performed on a 3-Tesla scanner and used to derive T2 and SFF maps. An ex vivo experiment was performed using bovine bone; different numbers of holes (4, 6, 8, 10, and 12) were drilled separately on the articular surface, and SFF values were compared among the drilled areas. In a clinical study, 16 osteoarthritis patients underwent sagittal 3D fast spinecho (FSE) and MRF scanning, and knee cartilage segmentation was performed on each image. For morphologic analysis, fluid-excluded images of the SFF (FEISFF) and T2 maps (FEIT2) were generated using the cartilage segmentations, and the whole-organ magnetic resonance imaging score (WORMS) of each FEI and 3D FSE image were compared using the kappa coefficient. For quantitative analysis, intact cartilage volumes in the SFF (VSFF) and T2 maps (VT2) were calculated, and their correlations with reference to the actual cartilage volume on 3D FSE images (V3D) were evaluated.

RESULTS

In the ex vivo experiment, the SFF value increased as the number of holes increased. The kappa coefficients of the WORMS were 0.80 and 0.64 in the SFF and T2 maps, respectively, and substantial to almost perfect agreement was observed in the medial tibiofemoral joint. The V3D-VSFF and V3D-VT2 correlation coefficients differed by 0.03 or more in the medial tibiofemoral joint.

CONCLUSION

The MRF-derived SFF map can feasibly evaluate small, invisible cartilage defects and quantify cartilage volumes.

Trajectory of metabolic syndrome and its association with knee pain in middle-aged adults

OBJECTIVE

Metabolic syndrome (MetS) is characterised by the clustering of central obesity with metabolic abnormalities. We aimed to describe the association of MetS and trajectories of MetS over 10-13 years with knee symptoms in general population-based middle-aged adults.

METHODS

Fasting blood biochemistry, waist circumference and blood pressure measures were collected during Childhood Determinants of Adult Health (CDAH)-1 study (year:2004-6; n = 2447; mean age:31.48 ± 2.60) and after 10-13 year at CDAH-3 (year:2014-2019; n = 1549; mean age:44 ± 2.90). Participants were defined as having MetS as per International Diabetes Federation (IDF) definition. Knee symptoms were assessed using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale at CDAH-3 (mid-adulthood).

RESULTS

The prevalence of MetS increased from 8 % at young adulthood (female:52.06 %) to 13 % in mid-adulthood (female:53.78 %) over 10-13 years. Presence of MetS at mid-adulthood was associated with knee symptoms at mid-adulthood [ratio of means (RoM): 1.33; 95%CI:1.27,1.39]. Four MetS trajectories were identified-'No MetS' (85.01 %); 'Improved MetS' (2.14 %), 'Incident MetS' (8.81 %), and 'Persistent MetS, (4.04 %). Compared to 'No MetS', 'Persistent MetS' [RoM:1.15; 95%CI:1.06,1.25], 'Incident MetS' [RoM:1.56; 95%CI:1.48,1.65], and 'Improved MetS' [RoM:1.22; 95%CI:1.05,1.41] was associated with higher knee symptoms. Notably, 'Incident MetS' was strongly associated with knee symptoms [RoM: 1.56; 95%CI:1.48,1.65] and pain [RoM:1.52; 95%CI:1.37,1.70] at mid-adulthood.

CONCLUSION

In this sample of middle-aged adults, there was a significant positive association between MetS and knee symptoms. Relative to those without MetS at either life stage, the elevation in mean knee pain scores was more pronounced for those who developed MetS after young adulthood than for those who had MetS in young adulthood.