A new ex vivo human model of osteoarthritis cartilage calcification.

OBJECTIVE: Cartilage pathologic calcification is a hallmark of osteoarthritis (OA). Here, we aimed to describe a new ex vivo human model to study the progression of cartilage calcification. METHOD: Cartilage explants (n = 11), as well as primary chondrocytes (n = 3), were obtained from OA patients undergoing knee replacement. Explants and chondrocytes were cultured in control (NT) or calcification (CM) medium (supplemented with ascorbic acid and ß-glycerophosphate). Calcification was evaluated by micro-CT scan at day 0 and 21 in explants, and by Alizarin red staining in chondrocyte monolayers. Raman spectrometry allowed characterization of the crystal type. Interleukin-6 (IL-6) secretion in explant and cell supernatants was measured by ELISA. Finally, matrix degradation was evaluated by Safranin-O staining of explant sections and by glycosaminoglycans (GAG) release in supernatants. RESULTS: Micro-CT scan showed calcifications in all explants at baseline (day 0), which in the CM group increased significantly in number and size after 21 days compared with the NT group. Raman spectrometry revealed that crystals were exclusively basic calcium phosphate crystals (carbonated hydroxyapatite) both in NT and CM. IL-6 secretion was significantly increased in calcifying conditions. Finally, CM significantly increased cartilage catabolism as assessed by decreased Safranin-O staining of tissue explants and increased GAG release in supernatants. CM effects (enhanced calcification, IL-6 secretion and proteoglycans turn-over) were recapitulated in vitro in OA chondrocytes. CONCLUSIONS: We have described a new ex vivo human model of cartilage calcification that can summurize the triad of events seen during osteoarthritis progression, i.e. calcification, inflammation, and cartilage degradation. This model will allow the identification of new anti-calcification compounds.

Patient groups in Rheumatoid arthritis identified by deep learning respond differently to biologic or targeted synthetic DMARDs.

Cycling of biologic or targeted synthetic disease modifying antirheumatic drugs (b/tsDMARDs) in rheumatoid arthritis (RA) patients due to non-response is a problem preventing and delaying disease control. We aimed to assess and validate treatment response of b/tsDMARDs among clusters of RA patients identified by deep learning. We clustered RA patients clusters at first-time b/tsDMARD (cohort entry) in the Swiss Clinical Quality Management in Rheumatic Diseases registry (SCQM) [1999-2018]. We performed comparative effectiveness analyses of b/tsDMARDs (ref. adalimumab) using Cox proportional hazard regression. Within 15 months, we assessed b/tsDMARD stop due to non-response, and separately a ≥20% reduction in DAS28-esr as a response proxy. We validated results through stratified analyses according to most distinctive patient characteristics of clusters. Clusters comprised between 362 and 1481 patients (3516 unique patients). Stratified (validation) analyses confirmed comparative effectiveness results among clusters: Patients with ≥2 conventional synthetic DMARDs and prednisone at b/tsDMARD initiation, male patients, as well as patients with a lower disease burden responded better to tocilizumab than to adalimumab (hazard ratio [HR] 5.46, 95% confidence interval [CI] [1.76-16.94], and HR 8.44 [3.43-20.74], and HR 3.64 [2.04-6.49], respectively). Furthermore, seronegative women without use of prednisone at b/tsDMARD initiation as well as seropositive women with a higher disease burden and longer disease duration had a higher risk of non-response with golimumab (HR 2.36 [1.03-5.40] and HR 5.27 [2.10-13.21], respectively) than with adalimumab. Our results suggest that RA patient clusters identified by deep learning may have different responses to first-line b/tsDMARD. Thus, it may suggest optimal first-line b/tsDMARD for certain RA patients, which is a step forward towards personalizing treatment. However, further research in other cohorts is needed to verify our results.

[Electronic health record : challenges and possibilities]. / Dossier patient informatisé : défis et possibilités.

Information systems have been driving technological advances in healthcare, especially over the past two decades. Digital health is transforming care by emphasizing efficiency, accessibility, and integrating technology at every stage of the patient journey. The Electronic Health Record (EHR), a software used in hospitals or clinics, emerges as a cornerstone in this transformation by consolidating medical data to facilitate care coordination. This integration promises to enhance the quality of care and the patient-healthcare professional relationship, while presenting practical challenges such as increased documentation. In this article, we explore various aspects of the EHR, addressing its challenges and potential adaptations in our practice.

Les systèmes d'information ont été des moteurs d'avancées technologiques en santé, surtout au cours des deux dernières décennies. La santé numérique révolutionne les soins en mettant l'accent sur l'efficacité et l'accessibilité, intégrant la technologie à chaque étape du parcours du patient. Le dossier patient informatisé (DPI), logiciel utilisé en milieu hospitalier ou dans un cabinet, émerge comme pivot de cette transformation en consolidant les données médicales pour faciliter la coordination des soins. Cette intégration promet d'améliorer la qualité des soins et la relation patient-professionnel de santé tout en posant des défis pratiques tels que la documentation accrue. Dans cet article, nous explorons divers aspects du DPI, abordant ses défis et les adaptations possibles dans notre pratique.

Conservative Trio-Therapy for Varus Knee Osteoarthritis: A Prospective Case-Study.

Background and Objectives: Knee osteoarthritis (OA) is a frequent cause of pain, functional limitations, and a common reason for surgical treatment, such as joint replacement. Conservative therapies can reduce pain and improve function; thus, delaying or even preventing surgical intervention. Various individual conservative therapies show benefits, but combination therapies remain underexplored. The aim of this prospective case-study was to assess the effect of a conservative combination therapy in patients with painful varus knee OA. Materials and Methods: With strong inclusion and exclusion criteria, nine patients with painful varus knee OA (mean age 56 years (range 51−63 years) were selected and monitored over six months, using the following clinical outcome scores: pain visual analog scale (VAS), Western Ontario and McMaster Universities osteoarthritis index (WOMAC score), short-form−36 items (SF-36) quality of life score, and the sports frequency score. All patients received a standardized conservative trio-therapy with varus-reducing hindfoot shoe-insoles with a lateral hindfoot wedge, oral viscosupplementation, and physiotherapy for six months. Results: The pain was reduced significantly from initial VAS values of 5.4 points (range, 3−10) to values of 0.6 points (range, 0−3; p < 0.01), at the end of treatment. After six months, seven out of nine patients reported no pain at all (VAS 0). The WOMAC score improved significantly, from initial values of 35 (range, 10−56) to values of 2 (range, 0−9; p < 0.01). The SF-36 score showed significant improvement after six months in all four domains of physical health (p < 0.01) and in two of the four domains of mental health (p < 0.05). The sports frequency score increased by at least one level in six out of nine patients after six months. Conclusions: The conservative trio-therapy in patients with varus knee OA showed positive initial clinical results: less pain, higher function, better quality of life, and higher sport activity. Further studies are required to evaluate the long-term effect.

[Assessment of secondary fibromyalgia in patients with rheumatoid arthritis or spondylarthritis]. / Évaluation de la fibromyalgie secondaire à la polyarthrite rhumatoïde ou la spondylarthrite.

Pain is one of the main factors assessed in most of the scores used to measure activity in rheumatoid arthritis (RA) and spondylo arthritis (SpA). However, the experience of pain is complex, subjective and influenced by many factors. Fibromyalgia (FM) is present in 16-38% of patients with inflammatory rheumatic diseases (IRD) and has been shown to significantly increase indices of disease activity, often preventing an adequate response to immunosuppressive treatments. Recognition of secondary FM is important to avoid overtreatment. This article explores the relationship between FM and IRD, and how to optimise the assessment and treatment of one in the presence of the other.

La douleur est l'un des principaux facteurs évalués dans la plupart des scores utilisés pour mesurer l'activité de la polyarthrite rhumatoïde (PR) et des spondylarthrites (SpA). Cependant, l'expérience de la douleur est complexe, subjective et influencée par de nombreux facteurs. La fibromyalgie (FM) est présente chez 16 à 38 % des patients atteints de maladies rhumatismales inflammatoires (MRI) et il a été démontré qu'elle augmente de manière significative les indices d'activité de la maladie, empêchant souvent une réponse adéquate aux traitements immunosuppresseurs. La reconnaissance de la FM secondaire est importante pour éviter le surtraitement. Cet article explore la relation entre la FM et les MRI, et comment optimiser l'évaluation et le traitement de l'une en présence de l'autre.

Are patients with hypermobile Ehlers-Danlos syndrome or hypermobility spectrum disorder so different?

Diagnosing hypermobile Ehlers-Danlos syndrome (hEDS) remains challenging, despite new 2017 criteria. Patients not fulfilling these criteria are considered to have hypermobile spectrum disorder (HSD). Our first aim was to evaluate whether patients hEDS were more severely affected and had higher prevalence of extra-articular manifestations than HSD. Second aim was to compare their outcome after coordinated physical therapy. Patients fulfilling hEDS/HSD criteria were included in this real-life prospective cohort (November 2017/April 2019). They completed a 16-item Clinical Severity Score (CSS-16). We recorded bone involvement, neuropathic pain (DN4) and symptoms of mast cell disorders (MCAS) as extra-articular manifestations. After a standardized initial evaluation (T0), all patients were offered the same coordinated physical therapy, were followed-up at 6 months (T1) and at least 1 year later (T2), and were asked whether or not their condition had subjectively improved at T2. We included 97 patients (61 hEDS, 36 HSD). Median age was 40 (range 18-73); 92.7% were females. Three items from CSS-16 (pain, motricity problems, and bleeding) were significantly more severe with hEDS than HSD. Bone fragility, neuropathic pain and MCAS were equally prevalent. At T2 (20 months [range 18-26]) 54% of patients reported improvement (no difference between groups). On multivariable analysis, only family history of hypermobility predicted (favorable) outcome (p = 0.01). hEDS and HDS patients showed similar disease severity score except for pain, motricity problems and bleeding, and similar spectrum of extra-articular manifestations. Long-term improvement was observed in > 50% of patients in both groups. These results add weight to a clinical pragmatic proposition to consider hEDS/HSD as a single entity that requires the same treatments.

[Artificial intelligence-supported treatment in rheumatology : Principles, current situation and perspectives]. / Künstliche Intelligenz-unterstützte Behandlung in der Rheumatologie : Grundlagen, aktueller Stand und Ausblick.

Computer-guided clinical decision support systems have been finding their way into practice for some time, mostly integrated into electronic medical records. The primary goals are to improve the quality of treatment, save time and avoid errors. These are mostly rule-based algorithms that recognize drug interactions or provide reminder functions. Through artificial intelligence (AI), clinical decision support systems can be disruptively further developed. New knowledge is constantly being created from data through machine learning in order to predict the individual course of a patient's disease, identify phenotypes or support treatment decisions. Such algorithms already exist for rheumatological diseases. Automated image recognition and disease prediction in rheumatoid arthritis are the most advanced; however, these have not yet been sufficiently tested or integrated into existing decision support systems. Rather than dictating the AI-assisted choice of treatment to the doctor, future clinical decision systems are seen as hybrid decision support, always involving both the expert and the patient. There is also a great need for security through comprehensible and auditable algorithms to sustainably guarantee the quality and transparency of AI-assisted treatment recommendations in the long term.

[Rheumatology update 2020: the focus was on Covid-19]. / Actualité en rhumatologie 2020 : l'accent a été mis sur le Covid-19.

In 2020, clinical studies have opened the way for several new treatment options in rheumatoid arthritis, psoriasis arthritis, spondylarthritis and lupus. However, this year was mainly characterized by the Covid-19 pandemic which had a substantial impact on rheumatology. The initial fear for immune-compromised patients undergoing more severe Covid-19 courses remained without evidence. The same was true for the hype of several rheumatic treatments such as Plaquenil or anti-IL-6 blockade which finally did not show efficacy in prospective trials for Covid-19 pneumonia. On the other side, notably the first confinement had a substantial negative impact on rheumatic patients. Our patients are still struggling with the consequences of prolonged immobilization, lack of physiotherapy, missing consultations and treatment adaption as well as social isolation and depression. Telemedicine and upcoming digital solutions compensated this gap at least partially. The post-Covid syndrome with persisting fibromyalgia-like symptoms potentially will join the spectrum of rheumatic disorders.

De nouvelles possibilités de traitement sont apparues pour diverses indications rhumatologiques en 2020. Cependant, l'année a été marquée par la pandémie. Après une incertitude initiale, le traitement médicamenteux des affections rhumatologiques pendant la pandémie peut être considéré comme sûr. Le premier confinement, en particulier, a entraîné une augmentation de l'activité de la maladie par l'arrêt des médicaments et l'immobilisation des patients atteints d'affections rhumatologiques. Le SARS-CoV-2 peut déclencher des phénomènes auto-immuns, en particulier l'apparition d'anticorps antiphospholipides et des événements thromboemboliques secondaires. Il faut désormais voir quelles seront les conséquences à long terme. Il est cependant probable que les évolutions chroniques de type fibromyalgie au sens d'un syndrome post-Covid-19 soient à l'avenir un sujet récurrent en rhumatologie.

[Update Osteoarthritis]. / Le point sur l'arthrose.

Osteoarthritis (OA) remains a prevalent and difficult to treat entity, mostly due to its different phenotypes. Varying constellations of mechanic, metabolic and extrinsic factors such as trauma are main drivers of OA. Anti-inflammatory therapy by anti-interleukin 1 did not show a clear effect neither in hand or knee OA whilst it seem to reduce joint replacement at least in a certain patient populations. Corticosteroids did reduce pain and methotrexate reduced structural progression in recent hand OA trials. More promising for mechanical knee OA are growth factors such as sprifermin or kartogenin which foster the differentiation of chondrocytes. New data are available on joint safety of the subcutaneously administered anti-nerve growth factor (NGF) molecule tanezumab. In OA treatment, pain, structure, and biomechanic impairment need to be addressed.

Au lieu d'un seul médicament, la prise en charge optimale de l'arthrose consiste en une thérapie combinée. Dans ce cadre, il faut cibler la douleur, les lésions structurelles et la biomécanique perturbée. Des progrès concrets ont été réalisés avec divers nouveaux agents thérapeutiques. Par exemple, la sécurité d'inhibiteurs du NGF (nerve growth factor) a été mieux évaluée lors du traitement de la douleur avec des doses plus faibles. Bien que le traitement anti-inflammatoire par inhibiteur de l'interleukine 1 n'ait pas eu d'effet positif clair à court terme sur l'arthrose de la main ou du genou, il semble réduire le taux de prothèses du genou et de la hanche, du moins chez certaines populations de patients. Des facteurs de croissance tels que le FGF-18 (fibroblast growth factor 18) se présentent comme de bons candidats pour le traitement médicamenteux de la structure du cartilage. Un meilleur phénotypage de l'arthrose, par exemple sur les plans mécanique, microcristallin et métabolique, est nécessaire pour obtenir un effet optimal.

[Arthritis 4.0†: The digital cycle has begun]. / Arthrite 4.0†: le cycle numérique est en marche.

Current digital solutions in rheumatology support patients in terms of information and communication. E-diagnosis and symptom checker potentially reduce the delay of diagnosis. Patient reported outcome is increasingly used to monitor disease activity. In future, motion tracker and other types of sensors e.g. in smartphones might provide further information in order to predict disease flares. Artificial intelligence will likely be used for disease stratification, prediction and treatment choice. Together a «â€…digital cycle ¼ including diagnosis, surveillance and treat-ment decision is going to be established. The role of the rheuma-tologists within this cycle needs to be defined.

En rhumatologie, les applications numériques visent actuellement avant tout à informer et à mieux communiquer avec les patients. A l'avenir, les aides électroniques au diagnostic aideront à établir plus rapidement des diagnostics rhumatologiques pour un traitement encore plus précoce. Aujourd'hui déjà, les patients atteints de polyarthrite rhumatoïde (PR) enregistrent l'activité de leur maladie sur leur smartphone. Ces données collectées par les smartphones, les dispositifs portables ou par l'intermédiaire de capteurs de diverses formes fournissent au moins indirectement des informations sur l'activité de la maladie et servent ainsi de biomarqueurs numériques. C'est cependant l'intelligence artificielle qui constitue le plus grand défi. Celle-ci nous permettra probablement de mieux comprendre et traiter les maladies rhumatologiques à l'avenir.

[Rheumatoid arthritis-associated interstitial lung disease†: new genetic data and therapeutic perspectives]. / Pneumopathie interstitielle dans la ­polyarthrite rhumatoïde†: nouvelles données génétiques et perspectives thérapeutiques.

Diffuse interstitial lung disease (ILD) is one of the most frequent extra-articular manifestation of rheumatoid arthritis (RA) and is an important factor of morbidity and mortality. However, the physiopathological mechanisms underlying RA-associated ILD remain poorly understood, and disease management is difficult in the absence of effective treatments and international guidelines. The recent identification of genetic variants and mutations similar to those observed in idiopathic pulmonary fibrosis (IPF), a disease affecting exclusively the lung, provides new insights into the understanding of RA-associated ILD. Furthermore, new antifibrotic drugs approved for the treatment of IPF, including pirfenidone and nintedanib, could also prove to be effective for RA-associated ILD. Studies are ongoing to confirm this hypothesis.

La pneumopathie interstitielle diffuse compte parmi les manifestations extra-articulaires les plus fréquentes de la polyarthrite rhumatoïde (PR), et elle est un facteur important de morbidité et de mortalité. Elle reste toutefois mal comprise du point de vue physiopathologique et sa prise en charge est difficile, faute de traitements efficaces et de directives internationales. L'identification récente de variants génétiques et de mutations similaires à ceux observés dans la fibrose pulmonaire idiopathique (FPI), une maladie touchant exclusivement le poumon, offre de nouvelles perspectives de compréhension de la pneumopathie interstitielle associée à la PR. Par ailleurs, les nouveaux traitements antifibrotiques disponibles pour la FPI (pirfénidone et nintédanib) pourraient s'avérer aussi utiles dans la pneumopathie interstitielle associée à la PR. Des études sont en cours pour le déterminer.

Alterations of Subchondral Bone Progenitor Cells in Human Knee and Hip Osteoarthritis Lead to a Bone Sclerosis Phenotype.

Subchondral bone tissue plays a key role in the initiation and progression of human and experimental osteoarthritis and has received considerable interest as a treatment target. Elevated bone turnover and remodeling leads to subchondral bone sclerosis that is characterized by an increase in bone material that is less mineralized. The aim of this study was to investigate whether perturbations in subchondral bone-resident progenitor cells might play a role in aberrant bone formation in osteoarthritis. Colony formation assays indicated similar clonogenicity of progenitor cells from non-sclerotic and sclerotic subchondral trabecular bone tissues of osteoarthritic knee and hip joints compared with controls from iliac crest bone. However, the osteogenic potential at the clonal level was approximately two-fold higher in osteoarthritis than controls. An osteogenic differentiation assay indicated an efficient induction of alkaline phosphatase activity but blunted in vitro matrix mineralization irrespective of the presence of sclerosis. Micro-computed tomography and histology demonstrated the formation of de novo calcified tissues by osteoblast-like cells in an ectopic implantation model. The expression of bone sialoprotein, a marker for osteoblast maturation and mineralization, was significantly less in sclerotic progenitor cells. Perturbation of resident progenitor cell function is associated with subchondral bone sclerosis and may be a treatment target for osteoarthritis.

[Pain and osteoarthritis]. / Douleurs et arthrose.

Osteoarthritis is one of the principal reasons for chronic pain worldwide. With the increase of life span, sedentary lifestyle and obesity, its socioeconomic impact is on the rise. The origin of osteoarthritis pain is heterogeneous and related to structural changes of all intra-and para-articular components. Optimization of biomechanics constitutes a principal pillar of therapeutic strategies. Although disease-modifying concepts are the main goal, symptomatic therapies may bring temporary relief. Identification of a neuropathic component of pain is important to implement the optimal pharmacotherapy. Based on today's knowledge, therapy evolves towards a multimodal approach, which should be implemented early on.

L'arthrose est l'une des causes principales de douleurs chroniques au niveau mondial. Avec l'augmentation de l'espérance de vie, la sédentarité et la surcharge pondérale, elle a un impact socioéconomique important. L'origine des douleurs arthrosiques est hétérogène et liée à des altérations structurelles et métaboliques de toutes les composantes articulaires et para-articulaires. L'optimalisation biomécanique constitue l'un des piliers thérapeutiques principaux. L'amélioration du cours de la maladie en soi doit être l'objectif primaire, mais des traitements symptomatiques peuvent apporter un soulagement temporaire. L'identification d'une composante neuropathique des douleurs est importante pour le choix du traitement pharmacologique. Aujourd'hui, la stratégie thérapeutique évolue vers une prise en charge multimodale qui doit être instaurée tôt et de manière conséquente.

[Reactive arthritis]. / Arthrite réactionnelle.

Reactive arthritis is usually regarded as a form of spondylarthritis. Patients generally present with an acute asymmetrical oligoarthritis following an episode of diarrhea or urethritis. The most frequent involved pathogens are Salmonella, Shigella, Campylobacter and Chlamydia trachomatis. Additional causative pathogens have been described. Non-steroidal anti-inflammatory drugs are the first line treatment for reactive arthritis, associated with physiotherapy. Occasionally, a short course of glucocorticoids or an intra-articular injection is needed. Chlamydia induced reactive arthritis should be treated with antibiotics. Some patients experience chronic persistent arthritis. These patients could benefit from a treatment with DMARDs such as sulfasalazine. In refractory cases, TNF-inhibitors are sometimes used.

L'arthrite réactionnelle est classée parmi les spondylo-arthropathies. Les patients présentent typiquement une oligoarthrite asymétrique suivant des diarrhées en cas d'infection à, par exemple, Salmonella ou Campylobacter ou suivant une infection urogénitale à Chlamydia trachomatis. Les patients peuvent aussi présenter des symptômes ophtalmiques ou cutanés. L'arthrite aiguë est traitée par anti-inflammatoires non stéroïdiens associés à de la physiothérapie. Des corticostéroïdes par voie intra-articulaire ou systémique sont parfois nécessaires. L'infection à Chlamydia trachomatis doit être traitée par antibiotiques. Chez une minorité de patients, l'arthrite devient chronique et nécessite l'introduction d'un traitement de fond, le plus souvent la sulfasalazine. Les anti-TNF sont parfois utilisés lorsque l'arthrite est réfractaire.

[Rheumatology. Checkpoint-induced autoimmunity - birth of a new disease]. / Rhumatologie. Autoimmunité induite par des checkpoints ­ naissance d'une nouvelle maladie.

Tumor cells express checkpoint proteins in order to prevent an immune reaction by T-cells. Checkpoint inhibitors are successfully used in oncology to unleash a cytotoxic immune response. Unfortunately this treatment increasingly leads to immune-related adverse events which resemble various primary autoimmune disorders known in rheumatology. Potentially, checkpoint dysfunction also underlies rheumatic diseases which would open the way for new treatment options to restore immune tolerance.

En exprimant certaines molécules régulatrices (dénommées « checkpoints ¼) à leur surface, les tumeurs parviennent à éviter la reconnaissance par le système immunitaire. L'inhibition de ces checkpoints peut donc permettre une réponse immunitaire, médiée par les lymphocytes T, contre les cellules tumorales. L'utilisation croissante des « checkpoint inhibitors ¼ en oncologie a permis d'augmenter considérablement la survie des patients, mais a également engendré des effets indésirables autoimmuns ressemblant sur le plan clinique aux maladies primaires que l'on connaît en rhumatologie. Des traitements corrigeant une dysfonction des checkpoints pourront probablement dans le futur également traiter des maladies autoimmunes et rétablir l'immunotolérance.

[Knee osteoarthritis : assessment and follow-up in family medicine]. / Bilan et suivi des patients avec arthrose du genou en médecine de famille.

Knee osteoarthritis is a frequent diagnosis in family medicine. Through a case vignette, we will review the tools available to family physicians to support their patients. Initial assessment can be simple, but it should be done rigorously and early when symptoms appear. There are ways to slow down osteoarthritis progression : weight reduction, physiotherapy, correction of misalignment. In terms of medication, non steroidal anti-inflammatory drugs (NSAID) are partially effective and must be used with caution to decrease risk of adverse events. Surgery can be proposed when symptoms become refractory. The mainstay of care is the education of the patient and exploration of his representations, which must guide physicians during follow-up.

La gonarthrose est un diagnostic fréquemment posé en médecine de famille. A travers une situation clinique, nous allons revoir les outils à disposition pour accompagner le patient. Le bilan initial peut être simple mais doit être effectué avec rigueur et le plus tôt possible. Les moyens de ralentir la progression de l'arthrose existent et sont à proposer : perte de poids, physiothérapie, correction des défauts d'alignement. Sur le plan pharmacologique, les anti-inflammatoires non stéroïdiens (AINS) sont partiellement efficaces et doivent être utilisés avec parcimonie afin de limiter les effets secondaires. La chirurgie est à proposer lorsque les symptômes deviennent réfractaires. L'éducation du patient et l'exploration de ses représentations sont des aspects importants qui doivent constituer le fil rouge de la prise en charge.

What drives osteoarthritis?-synovial versus subchondral bone pathology.

Subchondral bone and the synovium play an important role in the initiation and progression of OA. MRI often permits an early detection of synovial hypertrophy and bone marrow lesions, both of which can precede cartilage damage. Newer imaging modalities including CT osteoabsorptiometry and hybrid SPECT-CT have underlined the importance of bone in OA pathogenesis. The subchondral bone in OA undergoes an uncoupled remodelling process, which is notably characterized by macrophage infiltration and osteoclast formation. Concomitant increased osteoblast activity leads to spatial remineralization and osteosclerosis in end-stage disease. A plethora of metabolic and mechanical factors can lead to synovitis in OA. Synovial tissue is highly vascularized and thus exposed to systemic influences such as hypercholesterolaemia or low grade inflammation. This review aims to describe the current understanding of synovitis and subchondral bone pathology and their connection in OA.