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.

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.

Soft-tissue tuberculosis is an uncommon extrapulmonary manifestation and may be difficult to recognize when respiratory symptoms are absent. We report a 33-year-old, HIV-negative Sri Lankan woman without diabetes or known pharmacological immunosuppression who presented with three months of progressively enlarging, minimally tender superficial collections over the left wrist, right knee, and right ankle, accompanied by anorexia and unquantified weight loss. The swellings had minimal local inflammatory signs. She was anemic and hypoalbuminemic, with elevated inflammatory markers. Separate drainage specimens from all three sites were negative on acid-fast bacillus smear but positive for Mycobacterium (M.) tuberculosis complex by Xpert MTB/RIF, without rifampicin resistance; cultures from all three sites subsequently grew M. tuberculosis complex. Chest imaging showed bilateral loculated pleural effusions, nodular pleural thickening, and bilateral tree-in-bud nodules. These abnormalities were compatible with probable pleuropulmonary tuberculosis but were not diagnostic. Sputum investigations were negative, and pleural fluid could not be obtained. The case was classified as microbiologically confirmed multifocal soft-tissue tuberculosis with probable pleuropulmonary involvement. All three collections were drained, and first-line antituberculous therapy was initiated. At two months, the lesions remained resolved without recurrence or new lesions; appetite and well-being had improved; weight had increased by 4 kg; erythrocyte sedimentation rate had decreased from 125 to 36 mm/hour; and chest radiography showed near-complete resolution of the pleural effusions. Adherence was satisfactory, and no adverse effects were reported. These findings represented an early clinical and radiological response rather than definitive treatment success.

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.

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.

Knee osteoarthritis (OA) is traditionally evaluated using conventional radiography (Rx), which is limited to assessing structural bone changes and provides only an indirect measure of cartilage status through joint space width (JSW). Musculoskeletal ultrasonography (US) allows direct visualization of cartilage, marginal osteophytes, meniscal extrusion, and joint effusion, but its added value over standard radiography in bilateral knee assessment remains incompletely characterized. This observational, cross-sectional study prospectively included 30 symptomatic patients (60 knees; 24 women; median age 69 years, range 56-85) with clinically diagnosed knee OA, all evaluated by bilateral weight-bearing radiography and standardized US. Non-parametric tests were used (p < 0.05). Ultrasound detected marginal osteophytes more frequently than radiography in both knees (86.7% versus 56.7% on the left, p = 0.003; 83.3% versus 63.3% on the right, p = 0.014), with no osteophyte identified by radiography alone. Anterior femoral US cartilage thickness did not correlate with radiographic tibiofemoral medial JSW. Meniscal extrusion was associated with medial JSW narrowing in the right knee (p = 0.024), and joint effusion occurred only in knees with ultrasound-detected osteophytes (p = 0.003 both knees). Ultrasonography provides complementary structural and mechano-inflammatory information beyond radiography and may support a multiparametric characterization of knee OA.