To evaluate procedural safety as the primary outcome of ultrasound-guided synovial biopsy (UGSB) in a real-world, multicenter rheumatology setting. Secondary outcomes included technical tissue adequacy, histopathological yield, patient-reported outcomes, willingness to undergo repeat biopsy, clinical indications, and diagnostic contribution. This retrospective multicenter observational study included 87 patients who underwent UGSB for diagnostic or clinical indications. Demographic and clinical data, indication, biopsied joint, ultrasonographic findings, adverse events, and patient-reported outcomes using a Visual Analogue Scale (VAS 0-10) for pain, swelling, and limitation of motion were collected pre- and post-procedure. Adverse events and willingness to undergo repeat biopsy were recorded. Diagnoses were classified as rheumatoid arthritis (RA), undifferentiated arthritis, or other rheumatologic diseases. Of the 87 patients (57.5% female; median age 46 years, IQR 17), 47.1% were diagnosed with RA, 31.0% had undifferentiated arthritis, and 21.8% had other rheumatologic conditions. The knee was the most frequently biopsied joint (69.0%). Ultrasonographic grade ≥ 2 synovitis was detected in 83.3% and power Doppler signal in 33.3% of the 54 patients with available US data. Adequate synovial tissue for histopathological evaluation was obtained in 90% of procedures. Post-procedural VAS scores demonstrated significant reductions in pain, swelling, and limitation of motion compared with pre-biopsy assessments (p < 0.001 for all). Ultrasonographic synovitis severity correlated with the histological Krenn synovitis score (greyscale ρ = 0.31, p = 0.036; effusion ρ = 0.48, p = 0.001). Adverse events were infrequent and predominantly mild; transient pain was the most common complication (19.5%). Sensory impairment and vasovagal reactions each occurred in one patient (1.1%). No tendon, vascular, ligament, or muscle injury, hemarthrosis, infection, or thromboembolic complications were observed. Sixty-seven patients (77.0%) reported willingness to undergo repeat biopsy if clinically indicated. Following completion of the overall diagnostic work-up-integrating clinical, laboratory, imaging, microbiological, and histopathological findings-the proportion classified as having undifferentiated arthritis decreased from 31.0% to 13.8%. UGSB is a safe, feasible, and well-tolerated minimally invasive procedure with high patient acceptability and a high rate of adequate tissue acquisition across a broad spectrum of rheumatologic diseases. In selected patients with diagnostically challenging arthritis, synovial tissue analysis may provide histopathological or microbiological information that contributes to diagnostic clarification when integrated with the broader clinical work-up. These findings support the feasibility of UGSB in appropriately selected clinical settings and provide a basis for future prospective studies with standardized protocols.

Horses serve as a translational model for human osteoarthritis (OA) due to their comparable joint size, cartilage thickness, and incidence of naturally occurring disease. Overexpression of microRNA-181a-5p has been implicated in cartilage degradation in OA, and its inhibition using locked nucleic acid antisense oligonucleotides (LNA-miR-181a-5p ASOs) represents a potential therapeutic strategy. This study evaluated the safety of intraarticular (IA) LNA-miR-181a-5p ASO injection in clinically normal horse fetlock joints. Twelve horses were randomized to receive two IA injections, 28 days apart, of either low-dose [2000 µg (n = 6)] or high-dose [4000 µg (n = 6)] LNA-miR-181a-5p ASO. Over 56 days, variables assessed included physical examinations, joint assessments (effusion, circumference, temperature), lameness scores, and biofluid analyses. Physical and lameness evaluation variables remained similar to baseline and did not differ by dose (p > 0.05). Joint effusion was mildly increased in high-dose joints at Day 3 post-injection (p < 0.05), while circumference, temperature, and hematologic and biochemical variables remained similar to baseline, and did not differ by dose (p > 0.05). A transient, dose-independent increase (p < 0.05) in nucleated cell count at day 3 following each injection was observed, consistent with post-arthrocentesis inflammation. Synovial fluid IL-1β and PGE2 concentrations did not differ across doses and timepoints (p > 0.05). Although TNF-α concentrations were greater in the high-dose group (p < 0.05), values were variable across horses, even prior to treatment. Overall, IA LNA-miR-181a-5p ASO was well tolerated in clinically normal horse fetlocks, with only transient inflammatory changes, supporting its evaluation as a potential OA therapy.

Arthrogenic muscle inhibition (AMI) is a reflexive suppression of quadriceps motor drive that arises from abnormal joint afferent signaling rather than structural failure. It is a common and underrecognized barrier to recovery after knee injury and surgery, reported in more than half of acute anterior cruciate ligament (ACL) injuries and in roughly one-third of patients early after total knee arthroplasty. Even when a reconstruction, repair, or arthroplasty is technically successful, persistent inhibition can limit voluntary quadriceps activation, terminal knee extension, gait, and functional strength. This narrative review synthesizes the current evidence with a surgeon-facing perspective, organized around three areas: the neurophysiology of AMI, its clinical assessment and diagnosis, and current management strategies. The pathophysiology is time-dependent: acute AMI is predominantly a spinal reflex phenomenon driven by effusion, pain, inflammation, and altered mechanoreceptor input, whereas chronic AMI reflects corticospinal and cortical reorganization that responds less reliably to joint-directed treatment alone. AMI has no diagnostic gold standard and is recognized clinically after structural causes are excluded, with the Sonnery-Cottet (SANTI) classification providing a practical bedside grade and quantitative measures such as the central activation ratio reserved for research settings. Among management options, neuromuscular electrical stimulation carries the strongest evidence, supported by meta-analyses of randomized trials after ACL reconstruction, with earlier initiation associated with greater quadriceps strength recovery. Targeted activation exercises and cryotherapy are widely used and supported by observational and experimental work, though the evidence behind them is less direct. We consolidate this evidence into graded summary tables and a proposed bedside clinical pathway. Early recognition of AMI, particularly in high-risk perioperative windows, allows the surgeon to distinguish neuromuscular inhibition from mechanical block, guide patient-specific counseling, and coordinate treatment before recovery is compromised.

We present the case of an older adult man with prolonged fever of unknown origin and a persistent rectangular erythematous plaque, highlighting the diagnostic value of careful skin examination in patients with systemic inflammatory symptoms. This 70-year-old man with adult-onset endogenous eczema, hypertension, stage II upper rectal carcinoma following resection and adjuvant radiotherapy and chemotherapy and left hip avascular necrosis presented with fever persisting for 1 month following an upper respiratory tract infection. He developed generalised arthralgia and bilateral lower limb oedema, accompanied by poor oral intake. Initial treatment with amoxicillin- clavulanate and intravenous piperacillin-tazobactam provided temporary relief. Physical examination revealed generalised xerosis, with an incidental finding of an erythematous, non-tender, mildly indurated, rectangular patch measuring 10x20 cm at the lower back, unnoticeable by the patient. Bilateral inguinal lymph nodes measuring 2x1 cm were palpable. Bilateral pedal oedema with joint bogginess was also present. Laboratory investigations showed leucocytosis with neutrophilia without blasts, normochromic normocytic anaemia, hypoalbuminaemia, transaminitis and elevated inflammatory markers. Imaging (computed tomography and positron emission tomography scans) revealed mild left pleural effusion with multiple subcentimetre lymphadenopathies above and below the diaphragm. Tuberculosis, malignancy and autoimmune markers were negative. Skin biopsy showed scattered single dyskeratotic cells at the upper epidermis, with mild-to-moderate mixed perivascular inflammation including lymphocytes, neutrophils and eosinophils at the upper dermis. Atypical cutaneous manifestations may serve as a valuable clue to adult-onset Still's disease; however, the diagnosis should be established only after careful exclusion of infectious, malignant and autoimmune mimics.

Knee pain is one of the most prevalent musculoskeletal complaints and a leading cause of disability, particularly in middle-aged and older adults. Owing to the knee's complex anatomy and its essential role in weight bearing and locomotion, an accurate diagnosis of knee disorders remains challenging. Although radiography and magnetic resonance imaging are indispensable for structural evaluation, musculoskeletal ultrasound (US) has gained recognition as an effective first-line imaging modality because of its real-time visualization, dynamic assessment capability, absence of ionizing radiation, and cost-effectiveness. This guideline follows the EURO-MUSCULUS/USPRM framework to present a standardized, anatomy-based approach to knee ultrasonography, with emphasis on optimal patient positioning and systematic examination of the anterior, medial, lateral, and posterior compartments. Key anatomical structures - including the suprapatellar recess, quadriceps and patellar tendons, medial/lateral collateral ligaments, menisci, iliotibial band, posterior cruciate ligament, and the semimembranosus-gastrocnemius bursa - are detailed alongside their corresponding sonographic landmarks. Common knee pathologies, such as joint effusion, synovial hypertrophy, tendinopathy, ligament and meniscal tears, iliotibial band syndrome, and Baker's cysts, are illustrated with characteristic grayscale and Doppler US features. In addition, practical guidance on US-guided knee interventions, including suprapatellar joint injection, bursal injections, and Baker's cyst aspiration, is provided. By integrating standardized scanning protocols with interventional techniques, this guideline seeks to improve diagnostic reproducibility, enhance recognition of common knee pathologies, and promote the routine clinical adoption of musculoskeletal US in knee assessment.

Elbow pain arises from diverse tendinous, ligamentous, neural, and bursal disorders involving the lateral, medial, anterior, and posterior compartments. Because clinical symptoms frequently overlap - such as epicondylitis, distal biceps tendon injury, cubital tunnel syndrome, and olecranon bursitis - precise imaging is essential for accurate diagnosis and targeted management. Ultrasonography has become a first-line modality for elbow evaluation due to its high-resolution visualization, dynamic capability, and real-time interventional guidance. This article presents the Ultrasound Musculoskeletal Workshop in Taiwan (USMSIT)/Neuromuscular Ultrasound Workshop in Taiwan (NMUSIT) Fundamental Guide on Diagnostic and Interventional Elbow Ultrasonography, a standardized compartment-based protocol developed within the educational framework of the USMSIT and the NMUSIT. The guide systematically describes probe positioning, key anatomical landmarks, and normal sonoanatomy for assessment of the common extensor tendon, anterior joint recess, distal biceps tendon, common flexor tendon, cubital tunnel, and posterior elbow structures. Representative sonographic features of common pathologies - including tendinopathy, partial tear, joint effusion, ulnar neuropathy, and olecranon bursitis - are outlined, with emphasis on Doppler evaluation and dynamic maneuvers. In addition, step-by-step ultrasound-guided interventional techniques are summarized, including tendon injection, joint aspiration, ulnar nerve hydrodissection, and bursal aspiration. By integrating diagnostic and therapeutic principles within a structured framework, this guide provides a practical and reproducible reference for clinicians performing elbow ultrasonography.

We report a case of elbow pigmented villonodular synovitis (PVNS) combined with seronegative rheumatoid arthritis (SNRA) and review relevant literature to summarize the characteristics, treatment, and outcomes of this comorbidity. The patient was a 72-year-old female. She developed swelling and pain of the right elbow in 2002, and underwent surgical treatment. Postoperative histopathology confirmed PVNS. In 2007, she developed swelling and pain in the left elbow and underwent synovectomy, and synovectomy again yielded pathology consistent with PVNS. From 2021 onwards, she experienced recurrent bilateral knee pain and swelling. In June 2023, laboratory tests revealed markedly elevated inflammatory markers: C-reactive protein (CRP) 175.3 mg/L, erythrocyte sedimentation rate (ESR) 116 mm/h, hemoglobin 83 g/L, and platelet count 537×10[9]/L. Rheumatoid factor, anti-cyclic citrullinated peptideantibody, anti-keratin antibody, and anti-perinuclear factor were all negative. Right knee magnetic resonance imaging (MRI) showed severe degenerative changes, suprapatellar bursitis with large effusion, and ligamentous injuries. Given her prior PVNS history and knee MRI findings, right knee replacement was performed; however, intraoperatively no nodular or mass-like synovial proliferation was observed. Postoperative synovial pathology demonstrated massive chronic inflammatory cell infiltration, small vessel proliferation, and fibrinoid necrosis-findings typical of rheumatoid arthritis rather than PVNS. After surgery, the left knee continued to experience recurring pain and swelling. In April 2024, she developed swelling and pain in both wrists and right ankle joints. Ultrasound examinations showed synovial proliferation in the wrists, knees, ankles, and metatarsophalangeal joints, with abundant blood flow signals and bone erosion. The patient was diagnosed as SNRA combined with PVNS. Treatment with tocilizumab 400 mg intravenously monthly plus methotrexate 10 mg weekly was initiated. After three months, CRP decreased to 0.73 mg/L, ESR to 6 mm/h. A literature review using Wanfang, CNKI, and PubMed databases with keywords "rheumatoid arthritis" and "pigmented villonodular synovitis" identified only four previously reported cases of RA combined with PVNS. Including the present case, there were 5 cases (4 females, 1 male), the median age of PVNS onset was 45 (32.5-58.0) years. The knee was the most commonly affected joint (4/5 cases), followed by the elbow. PVNS preceded RA in two cases (by 3 and 12 years), rheumatoid arthritis (RA) preceded PVNS in two cases (by 3 and 15 years), and one case had simultaneous onset. Four of the five patients were seropositive for rheunatoid factor/anti-cyclic citrullinated peptide antibody (RF/anti-CCP); only the index case was seronegative. All five patients underwent synovial resection; two (40%) experienced postoperative recurrence. In conclusion, the coexistence of PVNS and SNRA is extremely rare and poses diagnostic challenges due to overlapping clinical manifestations. Physicians should consider the possibility of RA when a patient with PVNS develops symmetric polyarthritis, and conversely, suspect concomitant PVNS when a patient with RA has persistent monoarticular symptoms uncontrolled by disease-modifying therapy. Synovial fluid analysis, MRI findings, and especially histopathological examination are crucial for differentiation. Early recognition and appropriate immunotherapy can significantly improve prognosis.

While conventional radiography (CR) and computed tomography (CT) remain diagnostic staples in emergency settings, ultrasound (US) is a critical tool offering a rapid, dynamic, and noninvasive alternative for acute musculoskeletal (MSK) pathologies assessment. Prompt identification of conditions such as unstable fractures, soft tissue or muscular hematomas, joint effusions, and tendon ruptures is essential to prevent or mitigate long-term patient morbidity. This review summarizes the role of US in the emergency department, providing a practical overview of targeted scanning techniques and key sonographic signs. Additionally, common diagnostic pitfalls and effective escalation pathways are discussed to streamline clinical decision-making and optimize timely patient management.

Neuropathic arthropathy of the shoulder, or Charcot shoulder, is a rare and destructive neuroarthropathy resulting from impaired protective sensation and altered joint mechanics that is most commonly associated with syringomyelia. The pathogenesis is believed to involve both neurotraumatic and neurovascular mechanisms, resulting in progressive osseous destruction, joint instability, and soft tissue compromise. Clinical presentation varies, with painless swelling, joint effusion, crepitus, and progressive limitation in shoulder function commonly reported. Radiographic findings frequently demonstrate rapid joint destruction, humeral head collapse, fragmentation, and periarticular bone resorption. Accurate diagnosis requires a thorough clinical assessment combined with imaging and laboratory evaluation to exclude other causes of joint destruction. Advanced imaging is important in identifying associated neurologic abnormalities and early joint changes. Management strategies remain challenging and must be individualized based on symptom severity, functional demands, and the underlying neurologic condition. Non-operative treatment remains the first-line approach for many patients, particularly in early or less symptomatic stages. Surgical management may be considered in cases with severe pain, instability, or significant functional impairment. Although arthrodesis was historically the primary surgical option, advancements in shoulder arthroplasty and tendon transfer techniques have expanded treatment strategies.

Clinical and research imaging have been instrumental in shifting our understanding of osteoarthritis from a structural, cartilage-focused disorder to a whole-joint complex disease with biomechanical and inflammatory components. Initially, the only osteoarthritis imaging modality was x-ray; therefore, the focal point of diagnosis was the bone: osteophytes, sclerosis, but most importantly, the joint space narrowing. Soft-tissue visualization, dynamic imaging, and advanced image analysis techniques have shown that numerous other joint tissues and features are associated with osteoarthritis progression and symptom severity, and many of them appear before joint space narrowing is detectable. Inflammatory features like bone marrow lesions and effusion-synovitis have emerged as promising targets for intervention. The exact pathogenesis of and structure-modifying treatments for osteoarthritis remain elusive. Clinical and research imaging modalities are essential tools for monitoring the initiation and progression of the disease, identifying targets for intervention, and quantifying the impact of new treatments.