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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease 19 (COVID-19) pandemic, which is deeply affecting the whole world. In this new case for the scientific world, scientists are investigating the etiopathogenesis of viral infection-induced damage and have started to focus on the short and long-term immune system effects and alterations after SARS-CoV-2 infection. The case is here reported of a 53-year-old female patient with acute monoarthritis after SARS-CoV-2 infection, who responded adequately to 150 mg/day diclofenac treatment, and the available case reports are comprehensively reviewed. With the focus on arthritis after SARS-CoV2 infection, which emerges as a new pathological condition associated with COVID-19, it was aimed to examine the possible immunological mechanisms of post-COVID-19 arthritis based on the current data on SARS-CoV-2 and the known pathogenetic background of viral arthritis.

International audience; To characterize Lyme arthritis, with a focus on management, and outcome. Observational retrospective multicentre study in Western France, of all consecutive cases of Lyme arthritis, documented by Borrelia burgdorferi IgG on ELISA serological testing, confirmed by Western blot, with or without positive Borrelia PCR in synovial fluid, with no alternative diagnosis. We enrolled 52 patients (29 males), with a mean age of 43 +/- 19.4 years. Most patients had monoarthritis (n = 43, 82.7%), involving the knee (n = 51, 98.1%), with a median delay between symptoms onset and Lyme arthritis diagnosis of 5 months (interquartile range, 1.5-8). Synovial fluid analysis yielded median white cell count of 16,000/mm(3) (9230-40,500), and positive PCR in 16 cases (39%), for B. burgdorferi sensu stricto (n = 5), B. garinii (n = 5), B. afzelii (n = 3), and undetermined (n = 3). All patients received antibiotics, for a median duration of 28 days (21-30), with doxycycline (n = 44, 84.6%), ceftriaxone (n = 6, 11.5%), or amoxicillin (n = 2). Twelve patients (23.1%) also received intra-articular injection of glucocorticoids as first-line treatment. Of 47 patients with follow-up, 35 (74.5%) had complete resolution of Lyme arthritis. Lyme arthritis in Western Europe may be due to B. burgdorferi ss, B. afzelii, or B. garinii. Clinical presentation is similar to Lyme arthritis in North America (i.e. chronic knee monoarthritis), with low sensitivity of synovial fluid PCR (39%).

A total of 13 case reports of reactive arthritis reported in the literature in connection with coronavirus disease 2019 (COVID‑19) are reviewed. Men were affected more frequently than women. The arthritis was manifested 4-44 days after the infection or the occurrence of the COVID‑19 symptoms. Acute arthritis was monoarticular or oligoarticular. Only 1 out of 7 patients examined was human-leucocyte-antigen(HLA)-B27 positive. A direct viral infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could not be detected in the synovial fluid and was not investigated in the synovial membrane. The arthritis was successfully treated with nonsteroidal anti-inflammatory drugs and/or intra-articular or systemic corticosteroids. The pathogenesis of post-COVID‑19 reactive arthritis is unknown.Es werden 13 Fallberichte einer reaktiven Arthritis im Zusammenhang mit einer Coronavirus-Krankheit-2019 (COVID‑19) referiert. Männer sind häufiger betroffen als Frauen. Die Arthritis manifestiert sich 4 bis 44 Tage nach der Infektion bzw. dem Auftreten der COVID‑19-Symptome. Die akute Arthritis ist monoartikulär oder oligoartikulär. Nur einer von 7 untersuchten Patienten war Humanes-Leukozyten-Antigen(HLA)-B27-positiv. Eine direkte virale Infektion des Gelenkes mit „severe acute respiratory syndrome coronavirus 2“ (SARS-CoV‑2) wurde in der Synovialflüssigkeit nicht nachgewiesen und in der Synovialis nicht untersucht. Die Arthritis wurde mit nichtsteroidalen Antirheumatika und/oder intraartikulären oder systemischen Kortikosteroiden erfolgreich behandelt. Die Pathogenese der post-COVID‑19-reaktiven Arthritis ist ungeklärt.

ZusammenfassungEin Diabetiker, Träger eines Ports und mit Zustand nach Gonarthritis durch Pseudomonas aeruginosa, erlitt eine subakute Arthritis eines Handgelenks. Protrahiert gelang der kulturelle Nachweis von P. aeruginosa aus dem explantierten Port und dem betroffenen Gelenk. Der Fall zeigt, dass bei Patienten mit unklarer Handgelenkarthritis, Vorgeschichte einer septischen Arthritis mit P. aeruginosa und Risikofaktoren für eine hämatogene Streuung ein Rezidiv ausgeschlossen werden sollte. Die Therapie bestand aus Portexplantation, Débridement mit Synovialektomie des Gelenks und antibiotischer Therapie.

Nauclea diderrichii, is a common woody plant in Africa where it is traditionally used for the relief and treatment of multiple pain-related conditions. The aim was to evaluate the inflammatory and anti-arthritic properties of the aqueous extract of N. diderrichii stem bark. Carrageenan and formalin were used to induce inflammation while zymosan A was used to induce monoarthritis in rats. The extract was given orally at doses of 100, 200 and 400 mg/kg. The extract significantly reduced carrageenan-induced edema up to 6 h, with 61.94% (6th hour). The extract induces a significant inhibition of the formalin-induced edema from the 2nd to the 8th hour with 61.50% (2nd hour). In continuous treatment, the activity of the extract remains significant from the 2nd to the 10th day of treatment with 63.85% (9th day). The extract (400 mg/kg) induces a significant decrease of the organ weight while the body weight increases significantly. At 400 mg/kg, the extract significantly increases the levels of red blood cells, hemoglobin and proteins, as well as the catalase and SOD activities, then a significant decrease of the levels of white blood cells, lymphocytes, hematocrit, MDA and NO. Furthermore, the extract significantly inhibited zymosan A-induced edema from the 1st to the 5th day with 60.99% (5th day). The joints of the treated animals show a close to normal architecture compared to that of the untreated animals. These results demonstrate the anti-inflammatory and anti-arthritic properties of N. diderrichii and confirm its traditional use to relieve pain and inflammation.

Rheumatoid arthritis (RA) is a chronic autoimmune disease affecting primarily joints and an increased risk of developing malignant lymphomas in RA has been well reported. However, primary lymphoma in a joint in RA patient is rare. We report the case of a 65-year-old man with RA suffering from pain and swelling of left sternoclavicular (SC) joint, which was not relieved by adding low-dose glucocorticoid. Magnetic resonance imaging (MRI) showed a para-osseous soft tissue swelling around the SC joint and a fracture of proximal clavicle. Histology of the soft tissue demonstrated diffuse large B-cell lymphoma and the patient subsequently underwent R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy. He was successfully treated with six cycles of R-CHOP chemotherapy, with discontinuation of MTX, resulting in a complete response. We performed a literature review and identified nine cases of lymphoma which involved joints in patients with rheumatoid arthritis. This is the first described case of a primary large B-cell lymphoma involving the unilateral SC joint in a patient with RA, which was initially confused with aggravation of RA. Therefore, malignant lymphoma should be considered in the differential diagnosis when a RA patient develops monoarthritis with spontaneous fracture, even without B symptoms.

Kawasaki disease (KD) is associated with several musculoskeletal manifestations. Although arthritis has been reported to occur in 2.3-31% of children with KD, there is paucity of detailed studies on the subject. We report our experience on arthritis in children with KD. Data were collated from a review of records of patients diagnosed with KD and arthritis during the period January 1994-June 2019. Eight hundred sixty-five children (male:female 29:11) were diagnosed with KD during this period-of these, 40 (4.6%) had arthritis. Median day of diagnosis of KD was 17 days. Twenty-nine (72.5%), 8 (20%), and 3 (8.6%) children developed arthritis in acute, subacute, and convalescent phases of KD, respectively. Oligoarticular involvement was observed in 32 (80%) children and among these, 7 (20%) had monoarthritis. Predominant joints involved were knee (74.3%), ankle (40%), and hip (28.6%). Thirty-two children (80%) were treated with non-steroidal anti-inflammatory drugs (NSAIDs). Median duration of arthritis was 10 days (range, 2-180 days) with uneventful recovery in all cases. Three (7.5%) children had coronary artery ectasia which regressed on follow-up.Conclusion: Arthritis in KD is usually non-erosive, self-limiting, and responds well to a short course of NSAIDs.What is Known:• Arthritis has been reported to occur in 2.3-31% of children with KD.• Arthritis in KD is usually oligoarticular, non-erosive, and responds well to short course of non-steroidal anti-inflammatory drugs.What is New:• Children with KD and arthritis do not appear to be at increased risk of development of coronary artery abnormalities.• Arthritis in children with KD can result in diagnostic confusion, and diagnosis of KD may get delayed.

How oxidative stress contributes to neuro-inflammation and chronic pain is documented, and methane is reported to protect against ischemia-reperfusion injury in the nervous system via anti-inflammatory and antioxidant properties. We studied whether methane in the form of methane rich saline (MS) has analgesic effects in a monoarthritis (MA) rat model of chronic inflammatory pain. Single and repeated injections of MS (i.p.) reduced MA-induced mechanical allodynia and multiple methane treatments blocked activation of glial cells, decreased IL-1β and TNF-α production and MMP-2 activity, and upregulated IL-10 expression in the spinal cord on day 10 post-MA. Furthermore, MS reduced infiltrating T cells and expression of IFN-γ and suppressed MA-induced oxidative stress (MDA and 8-OHDG), and increased superoxide dismutase and catalase activity. Thus, MS may offer anti-inflammatory and antioxidant effects to reduce chronic inflammatory pain.

We determined the role of persistent monoarthritis of temporomandibular joint region (TMJ) on bilateral masseter muscle (MM) nociception in male rats using orofacial nocifensive behaviors, phosphorylated extracellular signal-regulated kinase and Fos induction at the trigeminal subnucleus caudalis/upper cervical spinal cord (Vc/C2) region in response to formalin injection to the MM region. TMJ inflammation was induced by local injection of CFA into the left TMJ region. Orofacial nocifensive behaviors evoked by formalin injection ipsilateral or contralateral to the TMJ inflammation appeared to be increased at 1–14 days or at 1, 10 and 14 days after induction of TMJ inflammation, respectively, while increases in behavioral duration were seen mainly in the late phase rather than the early phase. The number of pERK positive cells was investigated in superficial laminae at the Vc/C2 region at 3, 10, 20, 60 and 80 min after MM stimulation with formalin at 14 days after TMJ inflammation. TMJ-inflamed rats displayed greater responses of pERK expression by the ipsilateral MM stimulation at 3–60 min, while contralateral MM stimulation increased pERK expression at 3, 10 and 20 min compared to non-CFA rats. Fos expression by MM stimulation was increased at 14 days after induction of TMJ inflammation regardless of the affected side. These findings showed that persistent TMJ inflammation for 10 and 14 days is sufficient to enhance MM nociception indicated by behaviors and neural responses in superficial laminae at the Vc/C2 region.

Synovial arteriovenous malformation is rare. We present three children with recurrent monoarthritis secondary to synovial arteriovenous malformation. Two children underwent excision of arteriovenous malformation. Another child had diffuse arteriovenous malformation, which was inoperable. Synovial arteriovenous malformations should be considered in the differential diagnosis of monoarthritis, especially of the knee.

Increasing evidence suggests that T cells and glia participate in the process of neuropathic pain. However, little is known about the involvement of T cells or the interaction between glia and T cells at the molecular level. Here we investigated the phenotype of T cell infiltration into the spinal cord in inflammatory pain and explored potential crosstalk between glia and T cells. The establishment of monoarthritis produced T cell infiltration and astrocyte activation, exhibiting similar kinetics in the spinal cord. T-cell-deficient (Rag1−/−) mice significantly attenuated MA-induced mechanical allodynia and GFAP upregulation. Double immunofluorescence staining showed that CD3 mainly colocalized with interferon-gamma (IFN-γ). Western blot and flow cytometry showed that multiple intrathecal administrations of astrocytic inhibitor fluorocitrate decreased IFN-γ-production without decreasing T cell number in the spinal cord. Spinal IFN-γ blockade reduced MA-induced mechanical allodynia and astroglial activation. In contrast, treatment with rIFN-γ directly elicited persistent mechanical allodynia and upregulation of GFAP and pJNK1/2 in naïve rats. Furthermore, rIFN-γ upregulated the phosphorylation of NF-κB p65 in cultured astrocytes vitro and spinal dorsal horn vivo. The results suggest that Th1 cells and astrocytes maintain inflammatory pain and imply that there may be a positive feedback loop between these cells via IFN-γ.

Background Unusual forms of tuberculosis are common among immune-suppressed patients, leading to challenges in diagnosis and management. We present a Sri Lankan patient with systemic lupus erythematosis, investigated for chronic wrist pain with low inflammatory markers and without systemic symptoms, who was subsequently diagnosed to have tuberculosis of the joint. Case presentation A 31-year-old woman with systemic lupus erythematosis in remission was evaluated for chronic left wrist pain without significant examination findings on presentation. She did not have any constitutional symptoms. Basic investigations did not reveal any significant abnormalities. She was treated with increasing immunosuppression as for lupus related arthritis. Subsequently she developed a wrist effusion with high inflammatory markers, and was treated as septic arthritis. Synovial biopsy features suggested tuberculosis. The patient’s symptoms improved with surgical intervention and anti-tuberculosis treatment. Conclusion Tuberculosis should be considered in patients with systemic arthritis with unusual symptoms. Delayed diagnosis along with continuing immunosuppression can lead to extensive tissue damage. Clinically detectable effusions should be analyzed along with synovial biopsy in order to exclude concurrent infections. Radiography of the joint has poor sensitivity to detect early joint damage, but changes may be evident early on magnetic resonance imaging, sothis should be considered in patients with unusual features.

Reactive arthritis is an inflammatory joint disease induced by a preceding, sometimes asymptomatic bacterial infection outside the joints. With an estimated prevalence of 40/100,000 inhabitants, the disease primarily affects adults between the ages of 20 and 40 years. The clinical presentation is typically characterized by monoarthritis to oligoarthritis of the lower extremities with possible accompanying enthesitis, bursitis, tenosynovitis, sacroiliitis, dactylitis and rare extra-articular manifestations. Because of the similar clinical symptoms and an association with HLA-B27, reactive arthritis is attributed to the spondyloarthropathies. Typical triggering pathogens are Chlamydia, Salmonella, Yersinia, Shigella and Campylobacter. In about 20% of the cases the usually self-limiting disease becomes chronic. The pathogenesis is not yet understood in detail but it is currently assumed that the intracellular persistence of the pathogen causes an immune reaction resulting in arthritis. Common international diagnostic criteria do not yet exist; therefore the diagnosis is made largely on the basis of clinical findings, medical history and the direct and/or indirect pathogen detection. Several therapeutic options are used to treat reactive arthritis. Ongoing extra-articular infections, with the exception of enteritis should be treated with antibiotics. Besides symptom-orientated treatment of acute arthritis, in prolonged and chronic reactive arthritis an immunomodulatory therapy with steroids, sulfasalazine or methotrexate is used. The role of long-term antibiotic therapy for eradication of persistent intra-articular pathogens in chronic cases is the subject of current research.

The aim of the study was to evaluate the role of combined therapeutic pulsed ultrasound with intra-articular methotrexate as against pulsed ultrasound treatment program alone in the management of chronic synovitis in rheumatoid arthritis patients. A total of 38 patients were enrolled in the study. All patients were above 18 years of age with inadequate clinical response in the form of persistent monoarthritis. Of them, 24 completed the study. Patients were divided into two equal treatment groups: The first group (12 patients) received three consecutive intra-articular methotrexate injections and daily therapeutic pulsed ultrasound sessions, whereas the second group (12 patients) received daily therapeutic low-intensity pulsed ultrasound sessions. All patients were subjected to clinical, laboratory, and ultrasound evaluation before and after treatment. Patients were subjected to an ultrasound evaluation before and after treatment to detect synovial thickness, hot spots, erosions and effusion, with highly statistically significant difference observed in the number of swollen joints, tender joint count, visual analogue scale scores and synovial thickness at the wrist (P

BACKGROUND: The purpose of this study was to investigate the therapeutic efficacy of intravenously administered immunoselected STRO-3 + mesenchymal precursor cells (MPCs) on clinical scores, joint pathology and cytokine production in an ovine model of monoarthritis. METHODS: Monoarthritis was established in 16 adult merino sheep by administration of bovine type II collagen into the left hock joint following initial sensitization to this antigen. After 24 h, sheep were administered either 150 million allogeneic ovine MPCs (n = 8) or saline (n = 8) intravenously (IV). Lameness, joint swelling and pain were monitored and blood samples for leukocytes and cytokine levels were collected at intervals following arthritis induction. Animals were necropsied 14 days after arthritis induction and gross and histopathological evaluations were undertaken on tissues from the arthritic (left) and contralateral (right) joints. RESULTS: MPC-treated sheep demonstrated significantly reduced clinical signs of lameness, joint pain and swelling compared with saline controls. They also showed decreased cartilage erosions, synovial stromal cell activation and angiogenesis. This was accompanied by decreased infiltration of the synovial tissues by CD4⁺ lymphocytes and CD14⁺ monocytes/macrophages. Over the 3 days following joint arthropathy induction, the numbers of neutrophils circulating in the blood and plasma concentrations of activin A were significantly reduced in animals administered MPCs. CONCLUSIONS: The results of this study have demonstrated the capacity of IV-administered MPCs to mitigate the clinical signs and some of the inflammatory mediators responsible for joint tissue destruction in a large animal model of monoarthritis., This project was funded by a sponsored research agreement between the University of Melbourne and Mesoblast Ltd. AA was supported by a Libyan Government postgraduate scholarship, and LD was recipient of an Australian Postgraduate Award Scholarship.

Monoarthritis remains a diagnostic challenge in Rheumatology and Orthopedics. The author reports a case of septic arthritis due to Streptococcus bovis after several episodes of joint effusion treated with hyaluronic acid (Hylan G-F 20) and methylprednisolone acetate in a 69-year-old patient with liver cirrhosis due to hepatitis C virus. Neither adenoma of the colon nor endocarditis was present. The diagnostic possibilities for this case of monoarthritis, the pathologies related to the microorganism of interest to the rheumatologist, and the possible involvement of joint reaction to hyaluronic acid as a predisposing factor to joint effusion are discussed.

Skeletal involvement is described in 25% of patients with non-Hodgkin's lymphoma, typically as secondary, rarely as primary lymphoma of bone. Joint infiltration is very rare and monoarthritis can be a secondary synovial reaction to adjacent bone disease or direct synovial involvement. We describe an unusual case of monoarthritis of the elbow in a middle-aged man without signs and/or symptoms associated with malignancy and with no previous rheumatic disease. Synovial biopsy revealed a diffuse infiltrate of large atypical lymphocytic B cells diagnosed by morphological and immunohistochemical findings as a malignant lymphoma. Staging procedures including total body CT scan, bone marrow biopsy, technetium-99m methylene diphosphonate bone scintigraphy were normal. We discuss the case and the review of literature and suggest that in the evaluation of patients with an unclassified arthritis, synovial or bone biopsy should be strongly considered.

To investigate the effect of systemic administration dexmedetomidine, a selective alpha 2 adrenergic receptor (alpha(2)AR) agonist, on thermal hyperalgesia and spinal glial activation evoked by monoarthritis (MA).MA was induced by an intra-articular injection of complete Freund's adjuvant (CFA). Thermal hyperalgesia was measured by Hargreaves' test. The spinal glial activation status was analyzed by GFAP (an astrocytic marker) and Iba-1 (a microglial marker) immunohistochemistry or immunoblotting.Unilateral intra-articular injection of CFA produced a robust glial activation of astrocytes and microglia in the spinal cord, which was associated with the development and maintenance of thermal hyperalgesia. Intraperitoneal (ip) injection of dexmedetomidine (2.5 and 10 microg/kg) was repeatedly given once daily for 5 days with the first injection 60 min before intra-articular CFA. At the dose of 10 microg/kg, dexmedetomidine significantly attenuated MA-induced ipsilateral hyperalgesia from day 2 to day 5. MA-induced up-regulation of GFAP expression on both sides of the spinal dorsal horn was significantly suppressed by day 5 post-MA following dexmedetomidine application, whereas MA-induced Iba-1 up-regulation was only partially suppressed.Systemic dexmedetomidine inhibits the activation of spinal glia, which is possibly associated with its antihyperalgesia in monoarthritic rats.

This study explores the inflammatory response in various murine strains. Utilising several approaches, monoarthritis was induced in the knee, providing an inflammatory model relevant to arthritis.Acute (carrageenan/kaolin; C/K) or chronic inflammatory models (Freund's complete adjuvant; FCA) or antigen-induced arthritis (AIA), were induced by peri- and/or intra-articular injection.C/K elicited an acute inflammatory response in various strains of mice, with significant (P0.005) phenotypic variation. FCA induction provided a chronic inflammatory response. The magnitude of the response in both acute and chronic models was strain dependent, with BalbC exhibiting the most resistance to swelling in all models. AIA produced only an acute response in three strains tested.The data presented, demonstrating variation in the magnitude of acute and chronic inflammatory responses in different mice strains, allows informed selection of appropriate strains and models for future experimental studies.

Synovial metastases are rare events. Only 37 cases diagnosed by synovial fluid cytologic examination and/or by microscopic investigation of synovial biopsies have been previously reported in the literature. We report another case of shoulder chronic arthritis due to a recurrence of rectal adenocarcinoma and review previous published observations. Generally, this condition carries a poor prognosis with average patients survival of less than 5 months. The possibility of metastatic disease should be considered when an elderly person or patient with a history of previous malignancy presents with a chronic arthritis.

Apart from systemic symptoms of viral infection parvovirus B19, the infectious agent in erythema infectiosum, can lead to mainly self-limited acute and chronic arthropathy. Because mild subclinical features of the disease can be easily overlooked, joint affections might appear as isolated symptoms. We here report two cases of chronic monoarthritic symptoms of unknown origin, where immunohistochemical detection of B19-positive lymphocytic cells in the synovial tissue led to the diagnosis of B19 arthropathy. In conclusion, respective virus diagnostics should be considered even in chronic monosymptomatic arthritic lesions. The pathology of B19 arthropathy seems to be due to direct virus infection of cells within the synovia.

Juvenil chronic arthrits (JCA) is the most common chronic rheumatic disease in children an important cause of disability. When only one joint is involved it may be difficult to make an early diagnosis. A detailed history and clinical examination is important to reach a correct diagnosis and appropiated treatment.

Paraneoplastic rheumatic symptoms, caused by a malignancy, but not directly related to invasion by the tumor or its metastases are the result of a wide variety of tumor-derived biologic mediators. Recognition of paraneoplastic rheumatic syndromes is important, as it may lead to an early diagnosis of cancer. We report a 71-year-old patient with prostate cancer, presented with chronic monoarthritis of the left ankle and foot-drop. Monoarthritis and foot-drop was resistant to non-steroidal anti-inflammatory drugs and corticosteroids. After tumor resection, synovitis resolved and foot-drop disappeared almost totally.

A 7-year-old girl with polyarticular type juvenile rheumatoid arthritis (JRA) presented with acute onset of right hip pain with limited range of motion and fever within the past two days. She had received etanercept for more than one year. Percutaneous arthrocentesis was performed and showed a white blood cell count of 84150/μL in the synovial fluid, although the culture showed negative results. The fever and right hip pain completely resolved after antibiotic treatment. Herein, we report the first case of septic monoarthritis of JRA under etanercept treatment.

Infective arthritis (InfectA) has a variable geographical pattern. A 'Medline' search did not yield any earlier series on epidemiological pattern of InfectA from Kuwait or the Gulf region. Therefore, an observational prospective study of sequential cases seen over a period of 4 years was carried out. Of a total of 2021 patients seen during this period, 36 (1.8%) were diagnosed to have InfectA. There were 6 (16.7%) cases of neisserial and 30 (83.3%) of non-neisserial InfectA. Predisposing factors were seen in 17 (47.2%), all with non-neisserial InfectA. Microbiological diagnosis was proven in 15 (41.7%) cases, and included Neisseria gonorrhoeae in 5, Brucella spp. in 4, Staphylococcus aureus in 3, and Neisseria meningitidis, Salmonella spp. and Mycobacterium tuberculosis in 1 each. In the remaining 21 (58.3%) cases the diagnosis was made on clinical grounds and confirmed on therapeutic response. The most common presentation of neisserial InfectA was acute polyarthritis while that of non-neisserial InfectA was acute monoarthritis. All patients recovered with little disability and no mortality.

A case of an intraarticular epithelioid sarcoma is presented. The patient was a 35 year old man who presented with a 10 months history of a chronic monoarthritis. The MRI showed a diffuse lesion involving the synovial membrane of the knee. There was a marked increased signal on T2 weighted images. Most epithelioid sarcomas involve the subcutaneous tissues of the hands or feet. This presentation is unusual and this entity should be considered in the differential diagnosis of an intraarticular proliferative process.

A worldwide reemergence of tuberculosis is appreciable. Extrapulmonary tuberculosis has been observed to increase disproportionately from past incidence. One of the main attributing factors is the human immunodeficiency virus (HIV) infection. The objective of this study was to study clinical features, laboratory findings, and association with HIV infection in patients with peripheral tuberculous arthritis. The retrospective study was performed by reviewing the medical records of 27 patients with extraspinal tuberculous arthritis treated from January 1994 to December 2002. The diagnosis was made either by compatible clinical presentation and positive culture for Mycobacterium tuberculosis or histological finding of caseating granuloma in biopsy tissue or both. The average age of the patients' population was 49.3 years (range 27-74 years), made up of a 52% or 14 patients of male subjects. The mean duration of disease before seeking medical treatment was 10.2+11 weeks and from onset to diagnosis was 25 weeks. The most frequently affected joints were knees (36.6%) followed by wrists, ankles, shoulders, hips, sacroiliacs, and elbows, respectively. Monoarthritis was the main feature of this group, except for two patients who had two and three joints involvement, respectively. Dactylitis (tenosynovitis) was also found in two out of the 27 patients. Six patients (24%) had active pulmonary infiltration on chest X-ray. Of 11 patients with synovial polymerase chain reaction (PCR) testing for tuberculosis, seven patients had positive result. Only one patient with extraspinal tuberculous arthritis tested positive for HIV. Therefore, extraspinal tuberculous arthritis is observed to be usually present with chronic monoarthritis. The diagnosis is delayed in most occasions. PCR from synovial fluid may facilitate rapid diagnosis of tuberculous arthritis. Human immunodeficiency virus may not be a main contributing factor for extraspinal tuberculous arthritis.

Septic arthritis demands early diagnosis and correct treatment if the function of the joint is to be restored. Sometimes, as in fungal infection, signs and symptoms may be mild and the diagnosis delayed. Nevertheless, the outcome of fungal arthritis is severe and usually causes joint disability. The authors report two patients with chronic monoarthritis due to Sporothrix schenckii infection diagnosed by synovial fluid cultures. Their clinical presentation, laboratory and image findings, and their treatment and follow-up are analyzed and compared to previously reported cases. These cases illustrate the differential diagnosis of monoarthritis in immunocompetent adults and picture clinical features that could lead to early diagnosis and proper treatment.

Background The CatWalk system, a video based automated gait analysis system developed to evaluate footfall and gait changes in rodents, has been used for studying rodent models of arthritis, mainly the rat model. However, it has not been used to study static and dynamic gait parameters in mice with Complete Freund’s adjuvant (CFA). CFA is used extensively to induce arthritis in rodents including mice. Methods The CatWalk system was used to study gait of freely moving mice with CFA-induced monoarthritis and evaluate pharmacological pain relief in this model of arthritis. CFA (20 μl) was injected intra-articularly into the right hind (RH) limb ankle joint through the Achilles tendon of C57BL/6 mice. Results Mice had less regularity in their walking patterns after CFA inoculation compared to baseline walking patterns, which was significant at 2 days post inoculation (dpi). The mice also showed changes in static parameters (paw pressure (light intensity) and print area) as well as dynamic parameters (stance phase duration, swing phase duration and speed, and duty cycle). The ratio of the RH limb (ipslateral) to the left hind (LH) limb (contralateral) for paw pressure, print area, stance phase duration, duty cycle (stance phase duration/sum of stance and swing phase duration), and swing speed were significantly reduced compared to baseline ratios at 1–6 and/or 7 dpi. On the other hand, RH/LH limb ratio of the swing phase duration increased at 3 dpi compared to baseline values. Treatment with indomethacin (10 mg/kg) improved or restored the gait parameters of CFA inoculated mice i.e. similar to baseline values or LH limb. Conclusions These data show that the CatWalk system can be used to assess static and dynamic gait changes and pharmacological pain relief in freely moving mice with CFA-induced monoarthritis.

The study was conducted in filarial endemic area for various clinical presentations and diagnosis of occult filariasis. A total of 157 cases of various clinical presentations namely tropical pulmonary eosinophilia, monoarthritis, polyarthritis, glomerulonephropathy, tenosynovitis, inguinal lymphadenopathy, generalised lymphadenopathy, retroperitonial lymphadenopathy, endomyocardial fibrosis and acute conjunctivitis were screened for filarial antigen and antibody by enzyme linked immunosorbent assay (ELISA). Out of 157 cases, 107 cases were positive for antigen or antibody, suggesting the role of filarial infection in these clinical presentations. All the 107 cases were treated with diethylcarbamazine citrate (DEC) and some of the patients who were followed showed relief in signs and symptoms. Hence assay of filarial antigen and/or antibody may be useful for diagnosing occult filarial syndromes for better management and further appropriate treatment.

A 69-year-old female recently diagnosed as suffering from rheumatoid arthritis presented with a general flare-up of disease including a swollen left ankle. Investigation revealed the swelling to be due to a synovial sarcoma. This unusual cause should be considered in all cases of local joint flares in rheumatoid arthritis.

We describe the case of a young male who manifested Brucella suis osteomyelitis after a 5-year period of relapsing monoarthritis. We discuss some of the difficulties regarding the diagnosis of osteoarticular brucellosis and review presentation patterns of the disease.

The therapeutic indications for interferons (IFNs) have increased in recent years to include many different diseases of viral and malignant origin. Autoimmune phenomena may occur with IFN therapy, but arthritis is uncommon. In this case report, we describe a patient who developed monoarthritis in the knee after IFN-alpha therapy for chronic hepatitis B infection. A synovial fluid assay by polymerase chain reaction was negative for hepatitis B virus DNA and serum transaminase levels were normal as the arthritis developed. The patient was thought to have arthritis due to IFN-alpha treatment. A connection between IFN-alpha therapy and an induced autoimmune disorder is discussed.

The authors report and discuss the clinical and radiological features of a immunocompetent patient with chronic progressive monoarthritis tuberculosis of the hip without systemic symptoms such as fever, and weight loss presenting as caseating abscess and severe destruction of the hip joint, treated with resection arthroplasty.

Diabetes mellitus is associated with several non articular rheumatic conditions and is a cause of Charcot's arthropathy. We report three cases of long-standing insulin-dependent diabetics who developed an inflammatory monoarthritis of the ankle. There was no evidence of a peripheral neuropathy or sepsis. They were all seronegative for rheumatoid factor. In two the synovitis persisted; in the third there was a gradual resolution. This type of inflammatory synovitis has not been previously described in diabetes. It developed after a mean duration of diabetes of 34.3 years (range 18-52 years). We suggest that it may be associated with microvascular changes in diabetes, possibly involving hypoxic reperfusion.

In Lyme disease endemic areas, a noninvasive clinical prediction model to distinguish septic arthritis from Lyme arthritis would be useful, especially in children. A new study suggests that in highly selected patients, such prediction might be possible. But failure to recognize even a few cases of septic arthritis could have devastating consequences.

A 67-year-old man presented with acute monoarthritis of the right knee. Aspiration was carried out under aseptic precautions. This yielded a milky appearing fluid. Polarized microscopic examination confirmed uric acid crystals. The patient had a history of trauma to the joint. Acute monoarthritis of the knee can occur due to gout. Chylous effusions in the knee are rare. This combination of findings in the same joint has not been described in the literature. We emphasise the importance of history of trauma in acute monoarthritis. We discuss the unusual features of this case.

Introduction Hypoxia is a feature of the inflamed synovium in rheumatoid arthritis (RA). Intra-articular injection of hyaluronan (HA) may be considered a potential way to treat RA. However, the exact molecular mechanism of HA on decreased cellular responses to hypoxic environment is unclear. The present study has been designed to use the adjuvant-induced arthritis model to examine the effects of HA on the changes of immunohistochemical expressions of hypoxia-inducible factor-1alpha (HIF-1alpha), inducible nitric oxide synthase (iNOS), and matrix metalloproteinase-3 (MMP3) in the synovial tissues at the early phase of arthritic inflammation. Methods Monoarthritis was induced in adult male Sprague-Dawley (250-300 g) via intraarticular injection of complete Freund's adjuvant (CFA) into the tibiotarsal joint. The CFA-induction arthritis animals were divided into three groups: treatment (intraarticular injection of HA), placebo (intraarticular injection of saline) and controls (no treatments). Functional evaluations of edema and pain behavior, histology, and HIF-1alpha, iNOS, and MMP3 immunohistochemistry were performed before, after the first injection, three injections, and on the follow-up injection of the treatments. Results Intra-articular injection of HA also significantly suppressed the mechanical allodynia (p < 0.001) and overexpressions of HIF-1alpha (p < 0.001), iNOS (p = 0.004) and MMP3 (p < 0.001) immunoreactivity in synovium. Conclusions This study demonstrated that early intervention of HA is an effective protection against accumulation of inflammation-induced HIF-1alpha, iNOS, and MMP3 to limit erosive damage in CFA-induced model of arthritis.

The role of PGE2 in the sensitization of high-threshold tarsal joint mechanoreceptors (putative nociceptors) has been investigated in 11 arthritic and 16 normal rats. Injections of a low dose of Freund's complete adjuvant at multiple sites into the tissues surrounding the ankle joint induced a chronic unilateral monoarthritis in the injected limb. Measurements of both spontaneous activity and responses of tarsal joint mechanoreceptors to repeated graded mechanical stimuli were made. All of the mechanoreceptors examined had afferent fibres with conduction velocities in the C- or A-delta range. Using this new model of joint inflammation we have shown that lysine acetylsalicylate reduces the mechanical sensitivity of these joint mechanoreceptors and reduces the spontaneous activity in afferent nerve fibres. Prostaglandin E2 is unable to restore either the spontaneous activity in the afferent axon or the mechanical sensitivity of tarsal joint mechanoreceptors after lysine acetylsalicylate in the arthritic rat. Similarly, PGE2 does not sensitize or excite tarsal joint mechanoreceptors in the normal rat. In the normal rat, however, PGE2 potentiates the excitatory action of bradykinin and enhances the sensitizing effect of bradykinin on the responses of joint mechanoreceptors to mechanical stimulation when both substances are injected simultaneously. These results indicate that PGE2 is not important in the sensitization of these joint mechanoreceptors in this model of chronic joint inflammation but that in other circumstances PGE2 may be able to contribute to a sensitization of joint mechanoreceptors by enhancing the action of bradykinin.

Chronic pain is associated with N-methyl-D-aspartate (NMDA) receptor activation and downstream production of nitric oxide, which has a pivotal role in multisynaptic local circuit nociceptive processing in the spinal cord. The formation of nitric oxide is catalyzed by three major nitric oxide synthase (NOS) isoforms (neuronal, nNOS; inducible, iNOS; endothelial, eNOS), which are increased in the spinal cord of rodents subjected to some tonic and chronic forms of experimental pain. Despite the important role of NOS in spinal cord nociceptive transmission, there have been no studies exploring the effect of NMDA receptor blockade on NOS expression in the dorsal horn during chronic pain. Furthermore, NOS isoforms have not been fully characterized in the dorsal horn of animals subjected to arthritic pain. The aim of this work was therefore to study the expression of nNOS, iNOS and eNOS in the dorsal horns of monoarthritic rats, and the modifications in NOS expression induced by pharmacological blockade of spinal cord NMDA receptors. Monoarthritis was produced by intra-articular injection of complete Freund's adjuvant into the right tibio-tarsal joint. At week 4, monoarthritic rats were given either the competitive NMDA antagonist (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) or the uncompetitive NMDA antagonist ketamine. After 6 and 24 hours, animals were killed and posterior quadrants of the lumbar spinal cord were dissected. Sample tissues were homogenized and subjected to immunoblotting with anti-nNOS, anti-iNOS or anti-eNOS monoclonal antibodies. The nNOS isoform, but not the iNOS and eNOS isoforms, were detected in the dorsal horns of control rats. Monoarthritis increased the expression of nNOS, iNOS and eNOS in the dorsal horns ipsilateral and contralateral to the inflamed hindpaw. Intrathecal administration of CPP and ketamine reduced nNOS expression in monoarthritic rats but increased the expression of iNOS and eNOS. Results suggest that blockade of spinal cord NMDA receptors produces complex regulatory changes in the expression of NOS isoforms in monoarthritic rats that may be relevant for nitridergic neuronal/glial mechanisms involved in the pathophysiology of monoarthritis and in the pharmacological response to drugs interacting with NMDA receptors.

Rheumatoid arthritis (RA) is an autoimmune inflammatory disorder, characterised by joint swelling and diffuse chronic pain. RA patients display both hyperalgesia (an exaggerated painful response to a noxious stimulus) and allodynia (a painful response to a non-noxious stimulus). Collagen-induced arthritis (CIA) in the mouse is a well-established model of RA that may be useful in the study of inflammatory hyperalgesia. The aim of this study was to establish CIA as a model for studying inflammatory hyperalgesia, and to assess cellular changes that occur in the nociceptive system during the course of arthritis. Arthritis was induced by injection of 2 mg/ml bovine type II collagen in complete Freund's adjuvant into the base of the tail of male DBA/1 mice (n = 30). Behavioural analysis was performed for 28 days following arthritis onset. Mechanical and thermal hyperalgesia was assessed using the Plantar Von-Frey microprocessor system and the Hargreaves Plantar test, respectively. Animals were sacrificed at intervals after arthritis onset, and the lumbar spinal cord was collected and immunostained for astrocytes using antibodies to glial fibrillary acidic protein. Prior to onset of inflammation (post immunisation), little hyperalgesia occurred. Following arthritis onset there was a rapid decrease in both mechanical (Fig. ​(Fig.1)1) and thermal thresholds, reaching a maximum at 7–10 days after onset. Thermal threshold returned to naive levels 24 days following arthritis onset, while mechanical hyperalgesia remained throughout the study. Figure 1 The development of mechanical hyperalgesia in mice with collagen-induced arthritis. Increased glial fibrillary acidic protein expression was detected in the spinal cord from the day of arthritis onset, indicating that astrocytic activation occurs in CIA. This is in agreement with a well-established inflammatory model used for the study of pain, complete Freund's adjuvant-induced monoarthritis. Our results indicate that CIA can be used in the study of pain, and that changes occur in the nociceptive system during inflammation. As CIA is a well-established and validated model of RA, it may be of benefit to test analgesics aimed at inflammatory pain in this model and to understand the mechanisms involved in inflammatory hyperalgesia.

Therapies directed against tumour necrosis factor (TNF) are effective for the treatment of rheumatoid arthritis and reduce pain scores in this condition. In this study, we sought to explore mechanisms by which TNF contributes to inflammatory pain in an experimental model of arthritis. The effects of an anti-TNF agent, etanercept, on behavioural pain responses arising from rat monoarthritis induced by complete Freund's adjuvant were assessed and compared with expression of TNF receptors (TNFRs) by dorsal root ganglion (DRG) cells at corresponding time points. Etanercept had no effect on evoked pain responses in normal animals but exerted a differential effect on the thermal and mechanical hyperalgesia associated with rat arthritis induced by complete Freund's adjuvant (CFA). Joint inflammation was associated with increased TNFR1 and TNFR2 expression on DRG cells, which was maintained throughout the time course of the model. TNFR1 expression was increased in neuronal cells of the DRG bilaterally after arthritis induction. In contrast, TNFR2 expression occurred exclusively on non-neuronal cells of the macrophage–monocyte lineage, with cell numbers increasing in a TNF-dependent fashion during CFA-induced arthritis. A strong correlation was observed between numbers of macrophages and the development of mechanical hyperalgesia in CFA-induced arthritis. These results highlight the potential for TNF to play a vital role in inflammatory hyperalgesia, both by a direct action on neurons via TNFR1 and by facilitating the accumulation of macrophages in the DRG via a TNFR2-mediated pathway.

The severity and outcome of chronic arthritis is determined by the balance between destructive and homeostatic or anabolic molecular signaling pathways. Increasing evidence suggests a role for embryonic signaling pathways, essential for development and growth, in the maintenance of tissue homeostasis and in the induction of repair. Untimely or inappropriate activation of such pathways may also have a role in the progression of some diseases. Bone morphogenetic proteins (BMPs), originally identified as protein factors that induce a cascade of endochondral bone formation, have critical functions in cell proliferation, differentiation, adhesion and death. We have previously identified different BMPs in patients with chronic arthritis [1]. In this study, we evaluate the effect of shifting the balance in BMP signaling by reducing endogenous levels of noggin, a BMP antagonist, in a mouse model of systemic auto-immune arthritis (collagen-induced arthritis [CIA]), a model of cartilage destruction (methylated BSA [mBSA]-induced monoarthritis) and a model of ankylosing enthesitis and spondyloarthritis (spontaneous arthritis in male DBA/1 mice).

Fibroblasts can be isolated from rheumatoid arthritis (RA) synovial fluid (Sfld), and these cells may be derived from the synovium. Although normal tissues do not express DR5 protein, most cancerous tissues express high levels of DR5. Synovial fibroblasts from RA synovium share expression of DR5 protein with transformed cells. Our objective was to characterize fibroblasts from RA Sfld using an anti-DR5 monoclonal antibody. Sfld mononuclear cells were cultured from 50 patients with RA, 20 patients with seronegative arthritis, 20 patients with osteoarthritis (OA), and 15 patients with unclassified monoarthritis or oligoarthritis. Progressive growth of spindle-shaped cells was observed in some cultures. By the third passage 100% of cells were fibroblasts (Thy-1+, CD45-, CD68-). Fibroblasts were stained with a PE-conjugated anti-DR5 antibody and examined by flow cytometry. Fibroblasts grew from 35 of 50 RA Sfld samples. Twenty-six of these 35 were DR5+(> 95% positive cells; MFI relative to isotype control, 13.97 ± 2.5). Fibroblasts also grew from Sfld in six out of 20 seronegative arthritis, four out of 20 OA, and five out of 15 unclassified monoarthritis or oligoarthritis patients. All these were DR5- (MFI relative to isotype control, 1.2 ± 0.23). Ten out of 10 fibroblast lines from joint replacement surgery or synovectomy specimens of RA were DR5+. All fibroblast lines from the synovium of 10 OA patients were DR5-, as were fibroblasts from the skin of five healthy subjects. DR5+ Sfib cultures underwent apoptosis when treated in vitro with an anti-DR5 antibody, as determined by propidium iodide and annexin V staining. These results suggest that fibroblast-like cells from Sfld of RA are of at least two different lineages. Those expressing DR5 protein share this characteristic with transformed cells and with synovial fibroblasts from RA synovial membrane, and more likely derive from the synovium. The origin of DR5- Sfld fibroblasts remains to be determined. Because all RA patients with DR5- Sfld fibroblasts had active disease, we do not believe that DR5- cells are derived from 'burnt out' synovial membrane.

We present a case of intra-articular osteoid osteoma of the humerus simulating chronic monoarthritis of the elbow in an 18-year-old male right-handed recreational tennis player. CT revealed a well-defined nidus in the coronoid fossa. Microscopic examination of the synovium showed a lymphofollicular synovitis that resembled the synovitis in rheumatoid arthritis.

Bovine serum albumin (BSA) in complete Freund's adjuvant (CFA) was injected into the knee joints of previously BSA-sensitized guinea pigs and rabbits. The primary immune reaction to BSA prevemed secondary immune response to Trichinet(a Iarvae infection. We were unable to produce either eos(nophilia in the peripheral blood or antibodies against Trichinetla antigen (shown by complement fixation test). The additional injection of mediators of the inflammatory reaction or their precursors, e.g., complement component C5 and arachidonic acid, caused different histological pictures. C5 prodtrced a prolonged attire inflammatory phase with abundant neutrophils, whereas arachidonic acid did not significantly change the inflammatory response as compared to controls. The additional application of eosinophil-enriched preparation (EEP) caused a conspicuously reduced influx of monocytes/macrophages, a reduction of lymphocyte numbers, a prolonged influx of neutrophils, increased arylsnlfatase activity, earlier reduction of the inflam- matory process, and earlier onset of synoviocyte regeneration as compared to controls.