Imaging of Synovial Inflammation in Osteoarthritis, From the AJR Special Series on Inflammation.

Synovitis, inflammation of the synovial membrane, is a common manifestation of osteoarthritis (OA) and is recognized to play a role in the complex pathophysiology of OA. Increased recognition of the importance of synovitis in the OA disease process and its potential as a target for treatment has increased the need for noninvasive detection and characterization of synovitis using medical imaging. Numerous imaging methods can assess synovitis involvement in OA with varying sensitivity, specificity, and complexity. This article reviews the role of contrast-enhanced MRI, conventional MRI, novel unenhanced MRI, gray-scale ultrasound (US), and power Doppler US in the assessment of synovitis in patients with OA. The role of imaging in disease evaluation and the challenges of conventional imaging methods are discussed. We also provide an overview of the potential utility of emerging techniques for imaging of early inflammation and molecular inflammatory markers of synovitis, including quantitative MRI, superb microvascular imaging, and PET. The development of therapeutic treatments targeting inflammatory features, particularly in early OA, would greatly increase the importance of these imaging methods for clinical decision-making and evaluation of therapeutic efficacy.

A study to analyze the pattern of synovial lesions from synovial biopsies in a tertiary care centre.

INTRODUCTION: Synovium has been documented as a primary site of inflammation and a major effector organ in a variety of joint diseases. Study of simple technique like synovial biopsy can help in early diagnosis and treatment of diseases significantly improving outcome of patient in cases of rheumatoid arthritis, osteoarthritis, etc., Only limited data exist on utility of synovial biopsies. AIM AND OBJECTIVES: To analyze the pattern of synovial lesions to differentiate between different kinds of arthritis. Also, to identify early stages of arthritis so as to prevent unnecessary invasive surgical procedure. MATERIALS AND METHODS: It's a retrospective study to analyze 103 cases of synovial lesions diagnosed in last five years at a tertiary care orthopedic center. All synovial biopsies obtained mainly by open method and few by arthroscopic method, that came to the Dept of Pathology were included. Lesions were classified into four categories that is, inflammatory joint diseases, degenerative joint diseases, tumor-like conditions and tumors. RESULTS: Age group most affected was between 61 and 70 years, with male predominance. Osteoarthritis (OA) was the most common histopathological diagnosis. Early OA tissues showed greater lining layer thickness, vessel proliferation, and inflammation, while surface fibrin deposition along with fibrosis was noted in later stages. CONCLUSION: The histo-morphological observations made in this study may have important therapeutic implications for some patients during the early evolution of arthritis and could prevent unnecessary operative intervention of later stages.

Blood in the joint: effects of hemarthrosis on meniscus health and repair techniques.

Injury to the meniscus is common and frequently leads to the development of post-traumatic osteoarthritis (PTOA). Many times meniscus injuries occur coincident with anterior cruciate ligament (ACL) injuries and lead to a bloody joint effusion. Hemarthrosis, or bleeding into the joint, has been implicated in degeneration of joint tissues. The goal of this review paper is to understand the pathophysiology of blood-induced joint damage, the possible effects of blood on meniscus tissue, and the implications for current meniscus repair techniques that involve the introduction of blood-derived products into the joint. In this review, we illustrate the similarities in the pathophysiology of joint damage due to hemophilic arthropathy (HA) and osteoarthritis (OA). Although numerous studies have revealed the harmful effects of blood on cartilage and synovium, there is currently a gap in knowledge regarding the effects of hemarthrosis on meniscus tissue homeostasis, healing, and the development of PTOA following meniscus injury. Given that many meniscus repair techniques utilize blood-derived and marrow-derived products, it is essential to understand the effects of these factors on meniscus tissue and the whole joint organ to develop improved strategies to promote meniscus tissue repair and prevent PTOA development.

Synovial and pulmonary dysfunctions are induced by crosstalk of Smad and Erk pathways in an arthritis model.

In the current experiment, the effects of transforming growth factor (TGF)-ß1/Smad and ERK pathway crosstalk on synovial and pulmonary systems during rheumatoid arthritis have been investigated. For this purpose, rats were divided into normal control (NC) and model control (MC) groups. In the MC group, 0.1 ml Freund's complete adjuvant was injected intradermally into the right hind paw, and the resulting inflammation represented a rheumatoid arthritis model. Joint swelling and changes in lung functions were observed in arthritic rats. Synovial and lung were observed by light and electron microscopies. Enzyme-linked immunosorbent assays were used to detect TGF-ß1, interleukin (IL)-1ß, IL-4, IL-10, interferon-γ (IFN-γ), connective tissue growth factor (CTGF), and fibroblast growth factor (FGF). PCR, immunohistochemistry, and immunoblotting were used to detect changes in Smad and ERK pathways of synovial and lung tissues. Compared with the NC group, toe swelling was elevated in the MC group. Pulmonary functions FEV1, FEF50, FEF75, MMF, and PEF were decreased (P< 0.01). Serum cytokines IL-1ß, IL-4, TGF-ß1, and CTGF were increased, while IFN-γ, IL-10, Th1/Th2 cell ratio, and FGF were decreased (P< 0.01 or P< 0.05). Expression of TGF-ß1 and Smad2/3/4 mRNAs and TGF-ß1, TßRI, TßRII, Smad2/3, p-Smad2/3, and Smad4 proteins in the synovial membrane and lung tissue were increased, and expression of Smad7 mRNA and protein was decreased (P<0.01) or P<0.05). Expression of ERK2 mRNA and p-ERK1/2 protein was increased in the synovial membrane and lung tissue, and expression of ERK1/2 mRNAs and ERK1/2 and p-ERK1/2 proteins was increased in lung tissue (P< 0.01 or P< 0.05). Correlation analysis showed that FEV1 was negatively correlated with TGF-ß1 mRNA and protein in arthritic rats, FEF25 was negatively correlated with Smad4 protein, and FEF50 was negatively correlated with the TßRII protein, and FEF75, TGF-ß1 and Smad3 mRNAs. There was a negative correlation between Smad2/3 protein and a negative correlation between PEF and TGF-ß1 protein (P< 0.05). FEF50 and MMF were positively correlated with Smad7 mRNA (P< 0.05). FEV1 was negatively correlated with ERK2 mRNA, and FEF25 was negatively correlated with p-ERK1/2 protein. FEF75 and MMF were negatively correlated with ERK1/2 and p-ERK1/2, respectively (P< 0.05). ERK1 mRNA was positively correlated with Smad3 mRNA and TßRII protein, ERK2 mRNA was positively correlated with p-Smad2/3, and ERK1/2 protein was positively correlated with Smad2 mRNA, Smad4 protein, p-ERK1/2 protein, Smad4 mRNA, and p-Smad2/3 protein (P< 0.05). p-ERK1/2 protein was negatively correlated with Smad7 protein (P< 0.05). It is concluded that arthritic rats have synovial and systemic pulmonary damage. Smad and ERK pathway crosstalk leads to systemic lesions. Smad and ERK pathways are gradually activated by phosphorylation under the induction of the TGF-ß1 promoter, and then participate in transcriptional activities, leading to the increase in synovial inflammation of arthritis, pulmonary lesions, and decreases in lung functions.

Differentiation Potential of Synovial Mesenchymal Stem Cells Isolated From Hip Joints Affected by Femoroacetabular Impingement Syndrome Versus Osteoarthritis.

PURPOSE: To establish the characteristics of synovium-derived mesenchymal stem cells (MSCs) from the hip joints of patients with femoroacetabular impingement syndrome (FAIS) and osteoarthritis (OA), particularly their proliferation and differentiation potentials. We further investigated their functional differences. METHODS: Synovium samples were harvested from 21 patients with FAIS who underwent hip arthroscopic surgery and from 14 patients with OA who underwent total hip arthroplasty. The MSC number, colony-forming units, cell viability, and differentiation potential were compared. Real-time polymerase chain reaction assessed the differentiation potential into adipose, bone, and cartilage tissues. RESULTS: The number of colonies at a density of 104 at passage 0 from OA synovium was significantly greater than that from FAIS synovium (P < .01). However, their proliferation and viability were significantly lower than those of FAIS synovium cells (P = .0495). The expression of lipoprotein lipase mRNA in OA synovium cells was greater than that in FAIS synovium cells (P < .01). Meanwhile, the fraction of colonies positive for von Kossa and alkaline phosphatase staining, as well as the level of bone gamma-carboxyglutamate protein expression in OA synovium cells, were greater than those in FAIS synovium cells (P < .01). In chondrogenic pellet culture experiments, the expression of COL10A1 mRNA was lower in OA synovium than in FAIS synovium (P < .01). CONCLUSIONS: Synovial MSCs from patients with OA had greater colony numbers but less viability and proliferative potential. They also showed greater osteogenic and adipogenic potentials, whereas those from patients with FAIS showed greater chondrogenic potential. CLINICAL RELEVANCE: MSCs from patients with FAIS exhibited good potential as cell sources for stem cell therapy in case of cartilage damage in the hip joint.

Voxel-based Three-dimensional Segmentation of the Capsulo-synovium from Contrast-enhanced MRI Can Represent Clinical Impairments in Adhesive Capsulitis.

The purposes were to calculate total voxel volume of the entire capsulo-synovial enhanced portion on contrast-enhanced (CE) MRI in adhesive capsulitis, and to investigate its association with glenohumeral joint volume and passive range of motions (ROMs), which are a well-known diagnostic reference standard and clinical hallmark of this condition. Medical records of 169 consecutive patients who underwent ultrasound-guided intraarticular injection with adhesive capsulitis and CE-MRI to exclude other mimicking shoulder diseases were retrospectively reviewed. To calculate total voxel volume of entire capsulo-synovial enhanced portion on CE-MRI, voxel-based 3-dimensional (3D) segmentation was obtained semi-automatically using Fiji, an open-source image processing software. Pearson's correlation coefficients were analyzed. Sixty patients who met eligibility criteria were included. Total voxel volume showed a significant inverse correlation with the glenohumeral joint volume (r = -0.528, P < 0.001), forward elevation, external rotation, and abduction (r = -0.407, P = 0.001; r = -0.342, P = 0.007; r = -0.275, P = 0.034, respectively). Intra-observer and inter-observer reliabilities, measured by intraclass correlation coefficients (ICC), were excellent (ICC = 0.87 and 0.77, respectively). This study's results indicate that voxel-based 3D segmentation of entire capsulo-synovial enhanced portion from CE-MRI can represent the severity of clinical impairments, such as obliterated joint volume and limited passive ROMs in adhesive capsulitis.

Analysis of a mathematical model of rheumatoid arthritis.

Rheumatoid arthritis is an autoimmune disease characterized by inflammation in the synovial fluid within the synovial joint connecting two contiguous bony surfaces. The inflammation diffuses into the cartilage adjacent to each of the bony surfaces, resulting in their gradual destruction. The interface between the cartilage and the synovial fluid is an evolving free boundary. In this paper we consider a two-phase free boundary problem based on a simplified model of rheumatoid arthritis. We prove global existence and uniqueness of a solution, and derive properties of the free boundary. In particular it is proved that the free boundary increases in time, and the cartilage shrinks to zero as [Formula: see text], even under treatment by a drug. It is also shown in the reduced one-phased problem, with cartilage alone, that a larger prescribed inflammation function leads to a faster destruction of the cartilage.

Management of suprapatellar synovial plica, a common cause of anterior knee pain: a clinical review.

BACKGROUND AND AIM OF THE WORK: Suprapatellar synovial plica is caused by a congenital thickening of the synovial membrane and is generally asymptomatic. In the literature, suprapatellar plicae are described as one of the causes of anterior knee pain however, their real role in determining symptoms is controversial. The aim of the current paper is to describe the anatomy, classifications, pathophysiology, symptoms and management of suprapatellar plica syndrome, as well as the differential diagnosis from other causes of anterior knee pain. METHOD: Via a search within the MEDLINE/PubMed database, a current review was conducted, and the results summarized. RESULTS: Due to idiopathic, traumatic or inflammatory conditions, plicae can become pathological, causing anterior knee pain with possible knee clicking, swelling, giving way and locking after prolonged flexion of the knee. The diagnosis should be formulated based on an accurate medical history and clinical examination, followed by an appropriate imaging study. However, arthroscopy remains the "golden standard" for detecting all synovial plica. CONCLUSIONS: In patients with anterior knee pain, where doubt is present in the imaging investigation for intraarticular or periarticular lesions, pathological suprapatellar synovial plica must be suspected. The treatment should initially be conservative, but in cases where symptoms persist, patients should undergo arthroscopy to confirm diagnosis and to determine a suitable treatment. In the presence of pathological plica associated with cartilage damage of the femoral condyle or patella at the time of diagnostic arthroscopy, plicae excision leads to favourable results in a high number of cases.

Synovium-derived stromal cell-induced osteoclastogenesis: a potential osteoarthritis trigger.

Purpose: To shed light on the idea that mesenchymal stem/stromal cells (MSCs) recruited in synovium (SM) (i.e. Synovium-Derived Stromal Cells, SDSCs) could be involved in Osteoarthritis (OA) pathophysiology. Attention was also paid to a further stromal cell type with a peculiar ultrastructure called telocytes (TCs), whose role is far from clarified. Methods: In the present in vitro study, we compared SDSCs isolated from healthy and OA subjects in terms of phenotype, morphology and differentiation potential as well as in their capability to activate normal Peripheral Blood Mononuclear Cells (PBMCs). Histological, immunohistochemical and ultrastructural analyses were integrated by qRT-PCR and functional resorbing assays. Results: Our data demonstrated that both SDSC populations stimulated the formation of osteoclasts from PBMCs: the osteoclast-like cells generated by healthy-SDSCs via transwell co-cultures were inactive, while OA-derived SDSCs have a much greater effectiveness. Moreover, the presence of TCs was more evident in cultures obtained from OA subjects and suggests a possible involvement of these cells in OA. Conclusions: Osteoclastogenic differentiation capability of PBMCs from OA subjects, also induced by B synoviocytes has been already documented. Here we hypothesized that SDSCs, generally considered for their regenerative potential in cartilage lesions, have also a role in the onset/maintenance of OA. Clinical relevance: Our observations may represent an interesting opportunity for the development of a holistic approach for OA treatment, that considers the multifaceted capability of MSCs in relation to the environment.

Synovial cellular and molecular signatures stratify clinical response to csDMARD therapy and predict radiographic progression in early rheumatoid arthritis patients.

OBJECTIVES: To unravel the hierarchy of cellular/molecular pathways in the disease tissue of early, treatment-naïve rheumatoid arthritis (RA) patients and determine their relationship with clinical phenotypes and treatment response/outcomes longitudinally. METHODS: 144 consecutive treatment-naïve early RA patients (<12 months symptoms duration) underwent ultrasound-guided synovial biopsy before and 6 months after disease-modifying antirheumatic drug (DMARD) initiation. Synovial biopsies were analysed for cellular (immunohistology) and molecular (NanoString) characteristics and results compared with clinical and imaging outcomes. Differential gene expression analysis and logistic regression were applied to define variables correlating with treatment response and predicting radiographic progression. RESULTS: Cellular and molecular analyses of synovial tissue demonstrated for the first time in early RA the presence of three pathology groups: (1) lympho-myeloid dominated by the presence of B cells in addition to myeloid cells; (2) diffuse-myeloid with myeloid lineage predominance but poor in B cells nd (3) pauci-immune characterised by scanty immune cells and prevalent stromal cells. Longitudinal correlation of molecular signatures demonstrated that elevation of myeloid- and lymphoid-associated gene expression strongly correlated with disease activity, acute phase reactants and DMARD response at 6 months. Furthermore, elevation of synovial lymphoid-associated genes correlated with autoantibody positivity and elevation of osteoclast-targeting genes predicting radiographic joint damage progression at 12 months. Patients with predominant pauci-immune pathology showed less severe disease activity and radiographic progression. CONCLUSIONS: We demonstrate at disease presentation, prior to pathology modulation by therapy, the presence of specific cellular/molecular synovial signatures that delineate disease severity/progression and therapeutic response and may pave the way to more precise definition of RA taxonomy, therapeutic targeting and improved outcomes.

Time course analyses of structural changes in the infrapatellar fat pad and synovial membrane during inflammation-induced persistent pain development in rat knee joint.

BACKGROUND: Osteoarthritis (OA) is a common joint disease in aging societies, which is accompanied by chronic inflammation and degeneration of the joint structure. Inflammation of the infrapatellar fat pad (IFP) and synovial membrane (IFP surface) plays essential roles in persistent pain development in patients with OA. To identify the point during the inflammatory process critical for persistent pain development, we performed a time course histological analysis in a rat arthritis model. METHODS: Wistar rats received single intra-articular injection of monoiodoacetic acid (MIA, 0.2 or 1.0 mg/30 µL) in the right knees or phosphate-buffered saline (PBS, 30 µL) as a control in the left knees. Pain avoidance behaviors (weight-bearing asymmetry and tactile hypersensitivity of the plantar surface of the hind paw) were evaluated on days 0, 1, 3, 5, 7, and 14 after injection. Histological assessments of the knee joint were performed on days 0, 1, 3, 5, and 7 after MIA injection. RESULTS: Weight-bearing asymmetry was observed along with the onset of acute inflammation in both the low- (0.2 mg) and high-dose (1.0 mg) groups. In the low-dose group, weight-bearing asymmetry was completely reversed on day 10, indicating that joint pain seemed to alleviate between days 7 and 10. In contrast, we observed persistent joint pain after day 10 in the high-dose group. Histological assessments of the high-dose group indicated that the initial sign of inflammatory responses was observed in the perivascular region inside the IFP. Inflammatory cell infiltration from the perivascular region to the parenchymal region of the IFP was observed on day 3 and reached the IFP surface (synovial membrane) on day 7. Extensive fibrosis throughout the IFP was observed between days 5 and 7 after MIA injection. CONCLUSION: Our data indicated that acute joint pain occurs along with the onset of acute inflammatory process. Irreversible structural changes in the IFP, such as extensive fibrosis, are observed prior to persistent pain development. Thus, we consider that this process may play important roles in persistent pain development.

Rheumatoid arthritis revisited.

The generally accepted theory of the etiopathology of rheumatoid arthritis has not led to a breakthrough so far, and the root cause of RA is still unknown. Surgical experience does not support the idea that the damage in the joint is caused by synovitis. Synovial tissue does not spread on the surface of the cartilage and thus destroy it, and neither is the erosion caused by the synovial tissue. Macroscopically and microscopically synovitis in RA is no different to synovitis in arthrosis. Perhaps the etiopathogenesis should once more be reconsidered.

The Radiated Deep-frozen Xenogenic Meniscal Tissue Regenerated the Total Meniscus with Chondroprotection.

Meniscal allograft transplantation yields good and excellent results but is limited by donor availability. The purpose of the study was to evaluate the effectiveness of radiated deep-frozen xenogenic meniscal tissue (RDF-X) as an alternative graft choice in meniscal transplantation. The xenogenic meniscal tissues were harvested from the inner 1/3 part of the porcine meniscus and then irradiated and deeply frozen. The medial menisci of rabbits were replaced by the RDF-X. Meniscal allograft transplantation, meniscectomy and sham operation served as controls. Only a particular kind of rabbit-anti-pig antibody (molecular ranging 60-80 kD) was detected in the blood serum at week 2. The menisci of the group RDF-X grossly resembled the native tissue and the allograft meniscus with fibrocartilage regeneration at postoperative 1 year. Cell incorporation and the extracellular matrix were mostly observed at the surface and the inner 1/3 part of the newly regenerated RDF-X, which was different from the allograft. The biomechanical properties of the group RDF-X were also approximate to those of the native meniscus except for the compressive creep. In addition, chondroprotection was achieved after the RDF-X transplantation although the joint degeneration was not completely prevented. To conclude, the RDF-X could be a promising alternative for meniscal transplantation with similar tissue regeneration capacity to allograft transplantation and superior chondroprotection. The potential minor immunological rejection should be further studied before its clinical application.

The Tumor-Like Phenotype of Rheumatoid Synovium: Molecular Profiling and Prospects for Precision Medicine.

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by destructive hyperplasia of the synovium. Fibroblast-like synoviocytes (FLS) are a major component of synovial pannus and actively participate in the pathologic progression of RA. How rheumatoid FLS acquire and sustain such a uniquely aggressive phenotype remains poorly understood. We describe the current state of knowledge of the molecular alterations in rheumatoid FLS at the genomic, epigenomic, transcriptomic, proteomic, and metabolomic levels, which offers a means to reconstruct the pathways leading to rheumatoid pannus. Such data provide new pathologic insight and suggest means to more sensitively assess disease activity and response to therapy, as well as support new avenues for therapeutic development.

The biomechanics of subsynovial connective tissue in health and its role in carpal tunnel syndrome.

Carpal Tunnel Syndrome (CTS) is the most common surgically treated problem in the hand. Aside from the neuropathy itself, the most common findings are fibrosis of the subsynovial connective tissue (SSCT) and increased intra carpal tunnel pressure. Normally, the SSCT is a multilayer tissue interspersed among the carpal tendons and nerve. As the tendons move, successive SSCT layers are recruited, forming a gliding unit and providing a limit to differential movement. Exceeding this limit, damages the SSCT as has been shown in both cadavers and animal models. This damage leads to a non-inflammatory response with progressive fibrosis and nerve ischemia leaving the SSCT more susceptible to injury. Although the direct consequences for patients are not fully understood, ultrasound research shows that this fibrosis restricts median nerve displacement during tendon loading. This article aims to provide insights into the mechanical properties of SSCT described so far and place it in the context of CTS pathophysiology. A theoretical damage model concerning the SSCT is proposed showing a chain of events and vicious cycles that could lead to the nerve compression as it is found in CTS. Although not complete, this model could explain the pathophysiological pathway of idiopathic CTS.

[Review on Modern Repair Mechanism of Moxibustion for Treating Inflammatory Damage of Rheumatoid Arthritis].

Rheumatoid arthritis (RA) is a chronic inflammatory disease. Persistent inflammation of the synovial membrane is the main characteristic pathological symptom. Moxibustion for treating RA has achieved significant clinical effect in recent years. A large number of experimental studies have also shown that moxibustion promoted the repair of inflammatory damage induced by RA. Based on summarizing 10 years related literatures, the authors analyzed the repair mechanisms of moxibustion for inflammatory damage in RA from central mechanisms including glucocorticoid receptor, melatonine, hypothalamic-pituitary-adrenal axis, and cholinergic nerve to peripheral mechanisms including local inflammatory mediators, cytokine, and inflammatory cell signaling pathway, so as to provide evidences and reference for further research.

Obesity-associated metabolic syndrome spontaneously induces infiltration of pro-inflammatory macrophage in synovium and promotes osteoarthritis.

OBJECTIVES: Epidemiological and experimental studies have established obesity to be an important risk factor for osteoarthritis (OA), however, the mechanisms underlying this link remains largely unknown. Here, we studied local inflammatory responses in metabolic-OA. METHODS: Wistar rats were fed with control diet (CD) and high-carbohydrate, high-fat diet (HCHF) for period of 8 and 16 weeks. After euthanasia, the knees were examined to assess the articular cartilage changes and inflammation in synovial membrane. Further IHC was conducted to determine the macrophage-polarization status of the synovium. In addition, CD and HCHF synovial fluid was co-cultured with bone marrow-derived macrophages to assess the effect of synovial fluid inflammation on macrophage polarisation. RESULTS: Our study showed that, obesity induced by a high-carbohydrate, high-fat (HCHF) diet is associated with spontaneous and local inflammation of the synovial membranes in rats even before the cartilage degradation. This was followed by increased synovitis and increased macrophage infiltration into the synovium and a predominant elevation of pro-inflammatory M1 macrophages. In addition, bone marrow derived macrophages, cultured with synovial fluid collected from the knees of obese rats exhibited a pro-inflammatory M1 macrophage phenotype. CONCLUSION: Our study demonstrate a strong association between obesity and a dynamic immune response locally within synovial tissues. Furthermore, we have also identified synovial resident macrophages to play a vital role in the inflammation caused by the HCHF diet. Therefore, future therapeutic strategies targeted at the synovial macrophage phenotype may be the key to break the link between obesity and OA.

[Ramp lesions : Tips and tricks in diagnostics and therapy]. / Rampenläsionen : Tipps und Tricks in Diagnostik und Therapie.

There is an increasing biomechanical and anatomical understanding of the different types of meniscal lesions. Lesions of the posterior part of the medial meniscus in the meniscosynovial area have recently received increased attention. They generally occur in association with anterior cruciate ligament (ACL) injuries. They are often missed ("hidden lesions") due to the fact that they cannot be seen by routine anterior arthroscopic inspection. Furthermore, meniscosynovial lesions play a role in anteroposterior knee laxity and, as such, they may be a cause of failure of ACL reconstruction or of postoperative persistent laxity. Little information is available regarding their cause with respect to injury mechanism, natural history, biomechanical implications, healing potential and treatment options. This article presents an overview of the currently available knowledge of these ramp lesions, their possible pathomechanism, classification, biomechanical relevance as well as repair techniques.

Pigmented Villonodular Synovitis - Various Manifestations, Inconsistent Terminology and Treatment. Cases Study.

Pigmented villonodular synovitis (PVNS) as well as tenosynovial giant cell tumor (TGCT) are both diagnosed and described in two forms, namely a localized and diffuse type. They form a diverse group of proliferative lesions in articular synovium and tendon sheaths. The inconsistent terminology impedes communication between patients, orthopedic surgeons, radiologists and pathologists, leading to misunderstandings and delaying treatment. In this paper, we present three cases of PVNS/TGCT (involving the fourth toe extensor tendon sheath, hip joint after resurfacing and flexor hallucis longus tendon sheath) together with suggestions regarding the unification of the terminology as well as diagnosis and treatment.