Search Results (36)

Arthrogenic muscle inhibition (AMI), neurophysiological suppression of voluntary quadriceps activation triggered by joint effusion and inflammation, is consistently initiated within hours of any form of knee surgery. If not actively counteracted during the first two postoperative weeks, AMI may drive a cascade of neuromuscular, morphological, and biomechanical deficits that can persist for years, substantially increasing the risk of post-traumatic osteoarthritis, reinjury, and long-term functional disability. Emerging evidence indicates that preoperative patient-related factors, including baseline quadriceps strength, age, body mass index, and physical fitness, further modulate the rehabilitation response and should be considered in planning early postoperative protocols. This narrative review, which was not designed as a systematic review or meta-analysis and therefore does not include formal quality assessment or pooled statistical analysis, evaluates evidence for seven early-phase (0–2 weeks postoperative) knee muscle activation interventions: neuromuscular electrical stimulation (NMES), isometric quadriceps exercise, blood flow restriction (BFR) training, electromyographic (EMG) biofeedback, open and closed kinetic chain (OKC/CKC) exercise, cryotherapy, and continuous passive motion (CPM). Findings are synthesized against six clinically relevant dimensions, safety in the 0–2 week window, home-based usability, capacity to overcome AMI, requirement for volitional effort, objective monitoring capability, and progressive resistance, to characterize a consistent pattern: no single existing modality simultaneously meets all combined requirements for home deployment, volitional engagement, objective monitoring, and progressive resistance from postoperative day one. This collective unmet need provides direction for future device development and clinical research. Full article

Background: Neonatal septic arthritis is a rare but potentially devastating infection that can present with subtle clinical signs and rapidly progress to joint destruction, osteomyelitis, and permanent sequelae. We aimed to describe the clinical and microbiological characteristics, imaging findings, management, and follow-up outcomes of neonatal septic arthritis patients and to report ultrasonography (US) and magnetic resonance imaging (MRI) findings within the same cohort. Methods: This retrospective observational study was conducted in a tertiary neonatal intensive care unit and included neonates who were diagnosed with septic arthritis between January 2016 and December 2025. Demographic, clinical, laboratory, microbiological, imaging, treatment, and outcome data were systematically obtained from medical records. The diagnosis was based on compatible clinical findings supported by laboratory and/or microbiological evidence, with imaging used to support diagnosis and guide management. Results: Twelve neonates were included. The median gestational age was 36.5 weeks (26–40), and the median birth weight was 2435 g. The median symptom onset was 22 days of life. The hip (n = 4) and knee (n = 4) were most commonly affected. Pseudoparalysis and swelling were the most frequent findings. Synovial cultures were positive in 10/12 (Staphylococcus aureus, n = 7; methicillin-resistant Staphylococcus aureus (MRSA), n = 3), and blood cultures were positive in 6/12. US detected joint effusion in 33% of the patients, whereas MRI revealed inflammatory changes in all the patients. Concomitant osteomyelitis occurred in 5/12 patients. Orthopedic sequelae developed in 6/12; no mortality was observed. Conclusions: Neonatal septic arthritis is associated with a substantial risk of osteomyelitis and early sequelae. Delayed recognition may worsen outcomes. Normal ultrasonographic findings should not exclude the diagnosis when clinical suspicion persists, and MRI may provide complementary information for timely management. Full article

Background and Objectives: The role of tourniquet use in arthroscopic partial meniscectomy remains debatable. While traditionally adopted to enhance visualization and reduce intraoperative bleeding, concerns were raised regarding its impact on postoperative outcomes and potential adverse effects, such as muscle damage or delayed recovery. This systematic review aimed to evaluate whether the use of a tourniquet offers advantages in terms of surgical efficiency, patient recovery and complication rates in arthroscopic partial meniscectomy. Materials and Methods: A systematic review was conducted following PRISMA guidelines and registered in the PROSPERO database (CRD42025644740). A comprehensive literature search was performed in 5 databases including studies from the past 20 years. Only randomized controlled trials (RCTs) comparing tourniquet-assisted versus non-tourniquet procedures in adolescent and adult patients undergoing isolated arthroscopic partial meniscectomy matched our inclusion criteria and the analysis was performed on those. Methodological quality was assessed using the Cochrane RoB 2.0 tool. Data were synthesized either quantitatively or narratively, depending on the availability of statistical details. Results: Three RCTs with a total of 243 patients met the inclusion criteria. Operative time was shorter in tourniquet-assisted procedures in one study (p = 0.001), though comparable outcomes were achieved in non-tourniquet groups when pharmacological agents such as intra-articular adrenaline were used. No significant differences were observed between groups regarding postoperative pain (p = 0.22, p = 0.43), knee effusion (p = 0.96), range of motion (p = 0.91, p = 0.96), or time to return to functional activities (p = 0.9, p = 0.34, p = 0.23). Muscle damage, assessed by serum creatine phosphokinase CPK levels, did not differ between groups (p = 0.3, p = 0.093, p = 0.079). Intraoperative visibility and surgeon satisfaction rated higher in tourniquet groups (p = 0.002), although this was subjective and reported variably. No major tourniquet-related complications were recorded. Conclusions: The routine use of a tourniquet in arthroscopic partial meniscectomy provides limited intraoperative advantages and does not improve postoperative outcomes. Current evidence supports a selective rather than routine use of tourniquets, especially when pharmacological alternatives are available. Further high-quality studies are needed to define standardized protocols and assess long-term outcomes. Full article

Background/Objectives: Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by persistent synovial inflammation and vascular abnormalities. Emerging evidence suggests that dysbiosis of the microbiome contributes to the pathogenesis of this disease, while seasonal and meteorological variations represent significant factors influencing microbial community dynamics. However, the specific pathological mechanisms mediated by microbial populations within knee joint effusions of RA patients remain poorly elucidated. The present study employs 16S rRNA high-throughput sequencing technology to characterize seasonal variation patterns affecting microbial communities in knee joint effusions of RA patients and to investigate the relationship between microbial community structures and climatic lag effects. Methods: Microbial communities in knee joint effusion samples obtained from RA patients were analyzed using 16S rRNA high-throughput sequencing methodologies. A Distributed Lag Non-linear Model (DLNM) was applied to quantify the delayed effects of climatic variables on microbial community composition. The correlation patterns between meteorological parameters and community structure were elucidated through the integration of ridge regression and redundancy analysis (RDA). Preliminary identification of potential biomarkers was conducted using random forest algorithms. Results: According to research findings, the microbial composition of knee joint effusions in RA patients shows seasonal fluctuation patterns that are compatible with those seen in RA patients, even though there is no discernible seasonal change in β-diversity. Compared with samples obtained during other seasons, spring specimens exhibited significantly elevated relative abundances of both beneficial microorganisms and opportunistic pathogenic taxa. Random forest modeling identified Escherichia-Shigella and Curtobacterium as preliminary candidate biomarkers; however, external validation is required to establish their specificity as disease indicators. Further analysis revealed that although short-term meteorological fluctuations exert minimal influence on overall microbial diversity, specific alterations in mean wind speed (MWS) and relative humidity (RH) drive compositional changes in the microbial community, manifested as rapid responses from dominant bacterial taxa and compensatory buffering effects from rare taxa. Conclusions: This study suggests that the synovial cavity microbiota in RA patients may exhibit seasonal variation patterns that are statistically associated with environmental parameters, particularly humidity and temperature. Due to the inherent limitations of the cross-sectional study design, the preliminary candidate biomarkers identified herein require validation through external cohorts. Additional investigations incorporating healthy controls and osteoarthritis (OA) cohorts are necessary to confirm specificity and to elucidate the therapeutic potential of these microbial targets for RA microbiome interventions. Currently, insufficient evidence exists to establish causal relationships among microbial populations, joint pathology, and climatic factors. Longitudinal cohort studies are imperative to validate the temporal dynamics and clinical significance of these associations. Full article

Background/Objectives: Quadriceps arthrogenic muscle inhibition (AMI) represents a key impairment following anterior cruciate ligament reconstruction (ACLR), contributing to quadriceps weakness. Although transcutaneous electrical nerve stimulation (TENS) and percutaneous electrical nerve stimulation (PENS) have been primarily investigated for analgesia, their effects on quadriceps strength in the early postoperative period remain underexplored. Methods: This study describes a single-blinded, parallel-group randomized controlled trial investigating the short-term effects of a single high-frequency TENS session and a novel long-term potentiation (LTP) PENS protocol on quadriceps strength and related clinical outcomes after ACLR. Fifty-four participants will be randomly allocated using block randomization in a 1:1:1 ratio to one of three groups: a control group (conventional post-ACLR rehabilitation only), a TENS group (conventional rehabilitation plus a single high-frequency TENS session), or a PENS group (conventional rehabilitation plus a single LTP PENS session). Participants will receive neuromodulatory intervention during the sixth postoperative week. The LTP PENS protocol consists of five 5 s stimulation bursts at 100 Hz and 250 μs pulse width and has only been investigated once in patients with upper limb pathology, underscoring its novelty in a postoperative setting. Results: The primary outcome is quadriceps maximal voluntary isometric contraction, selected as a clinically relevant surrogate of quadriceps activation deficits associated with AMI. Secondary outcomes include pain intensity, pressure pain threshold, knee range of motion, thigh muscle perimeter, knee effusion and swelling, and self-reported function and knee-related quality of life. Outcomes will be assessed at baseline, immediately post-treatment, and 1 and 7 days post-intervention by a blinded assessor. Full article

Background and Objectives: Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disease, and progressive arthritis is its primary clinical manifestation. The role of human parvovirus B19 (B19V) infection in the progression of RA remains unclear. This study aims to investigate the association between B19V infection and viral genetic distribution in Vietnamese RA patients. Materials and Methods: 115 Vietnamese RA patients and 86 healthy controls (HCs) were enrolled in this observational study at the Thai Nguyen National Hospital from January 2019 to December 2021. B19V DNA was examined in serum and synovial fluid samples from RA patients using nested PCR and real-time PCR. B19V antibodies were detected in serum samples using ELISA. Results: B19V DNA was detected in the serum of 2 out of 115 (1.74%) RA patients but not in any HCs. Interestingly, B19V DNA was present in 12 out of 68 (17.65%) RA patients with knee effusion in their synovial fluid. Anti-B19V-IgG and anti-B19V-IgM were detected in the serum of 42.61% and 2.61% of RA patients, respectively, and in 24.42% and 12.79% of HCs, respectively. Anti-B19V-IgG levels were significantly higher in the serum of RA patients than in the serum of HCs (p = 0.007). However, anti-B19V-IgM was more commonly detected in HC serum than in RA patient serum (p = 0.006). Phylogenetic analysis showed that all B19V strains belonged to genotype 1 and subgenotype 1A. Conclusions: B19V infection is frequent in RA patients and suggests a contribution of B19V to the progression of RA, particularly in a B19V genotype-1- and subgenotype-1A-dependent manner and emphasises the need for early detection and management of B19V infection in RA patients. Full article

Introduction/Objectives: Osteoarthritis (OA) is a chronic systemic disease that affects the entire array of joint structures. It is one of the most common chronic, socially significant diseases, associated with a decline in the quality of life of patients and constantly increasing the cost of treatment. Clinical trial outcomes are largely inconclusive, and OA remains one of the few musculoskeletal diseases without an established disease-modifying therapy. One potential explanation is the use of ineffective tools for OA classification, patient stratification, and the assessment of disease progression. There is growing interest in musculoskeletal ultrasonography (MSK US), as it enables the dynamic visualization of the examined structures and gives information about both inflammatory and structural changes that have occurred. Determining the leading ultrasound phenotype, which depends on the most damaged tissue at a given time (bone, cartilage, synovial membrane, joint capsule, ligaments, tendons, menisci, etc.), can rationalize therapy use by selecting patients more suitable for specific treatments. This article aims to evaluate and summarize the potential of MSK US in the process of determining the clinical phenotype of OA and to emphasize the importance of this imaging modality in evaluating further therapeutic strategies. Method: A single-center prospective study conducted in the period of September 2023–June 2024 enrolled 259 consecutive patients with proven OA. The statistical program Minitab version 22.2.1 (2025) was used to analyze the data. The predominant and secondary phenotypes were tabulated for each OA localization and were presented numerically and as relative proportions (%). The rate of the most frequently occurring phenotypes was compared against that of the less frequent ones through paired z-tests. The initially acceptable type I error was set at 5%; it was further adjusted for the number of comparisons (Bonferroni). Results: The most frequent and predominant US phenotype for patients with knee OA was intra-articular effusion (n = 47, 37.90%). It was significantly higher compared to the rest of the US phenotypes: synovial proliferation (n = 22, 17.70%; p < 0.001), cartilage destruction (n = 26, 21%; p = 0.001), altered subchondral bone (n = 8, 6.50%; p < 0.001), extra-articular soft tissue changes (n = 12, 9.70%; p < 0.001), crystal deposits (n = 6, 4.8%; p < 0.001), and post-traumatic (n = 3, 2.40%; p < 0.001). The most common US phenotype for hip OA was altered subchondral bone (n = 32, 47.1%), with significant differences from intra-articular effusion (n = 12, 17.60%; p = 0.001), synovial proliferation (n = 5, 7.40; p = 0.001), cartilage destruction (n = 12, 17.60%; p = 0.001), extra-articular soft tissue changes (n = 3, 4.40%; p = 0.001), crystal deposits (n = 3, 4.40%; p = 0.001), and post-traumatic (n = 0). Altered subchondral bone was also the leading US phenotype for hand OA (n = 31, 55.40%), with significant differences compared to intra-articular effusion (n = 1, 1.80%; p < 0.001), synovial proliferation (n = 7, 12.50%; p < 0.001), cartilage destruction (n = 11, 19.60%; p < 0.001), extra-articular soft tissue changes (n = 2, 3.60%; p < 0.001), crystal deposits (n = 3, 5.40%; p < 0.001), and post-traumatic (n = 1, 1.80%, p < 0.001). For shoulder OA, extra-articular soft tissue changes were the most frequent (n = 8, 46.20%), followed by post-traumatic (n = 4, 30.70%), as the rate of both phenotypes was significantly higher compared to that of intra-articular effusion (n = 0), synovial proliferation (n = 0), cartilage destruction (n = 1, 7.70%; p = 0.003), and crystal deposits (n = 0). Conclusions: The therapeutic approach for OA is a dynamic and intricate process, for which the type of affected joint and the underlying pathogenetic mechanism at a specific stage of the disease’s evolution is essential. MSK US is one of the options for the clinical phenotyping of OA. Some of the suggested ultrasound subtypes may serve as the rationale for selecting a particular treatment. Full article

Arthrogenic muscle inhibition (AMI) is a neuromuscular impairment commonly observed following anterior cruciate ligament reconstruction (ACLR). This condition, characterized by persistent quadricep inhibition due to altered afferent feedback, significantly impacts neuromuscular recovery, delaying return to running and sport. Despite advancements in rehabilitation strategies, AMI may persist for months or even years after ACLR, leading to muscle strength asymmetries, altered biomechanics, and an increased risk of reinjury. The mechanisms underlying AMI involve both peripheral (joint effusion, mechanoreceptor dysfunction) and central (corticospinal inhibition, neuroplasticity alterations) components, which collectively hinder voluntary muscle activation and movement control. AMI alters gait mechanics, reduces knee stability, and promotes compensatory patterns that increase injury risk. Current return-to-sport protocols emphasize strength symmetry and functional performance but often neglect neuromuscular deficits. A comprehensive assessment integrating neuromuscular, biomechanical, and proprioceptive evaluations is needed at specific stages to optimize rehabilitation and minimize reinjury risk. Future research should explore targeted interventions such as neuromuscular stimulation, cognitive–motor training, and advanced gait analysis to mitigate AMI’s impact and facilitate a safer, more effective return to sport. Full article

Background: Runner’s dystonia (RD), a rare task-specific lower-limb dystonia affecting high-mileage runners, presents as abnormal lower-extremity muscle contractions during running. Treatment of RD is challenging and often confounded by significant diagnostic delays due to overlapping symptomatology with other conditions. This case series examines the relationship between stiff knee gait RD and musculoskeletal (MSK) knee pathology. Methods: Eight RD cases, evaluated at the NIH Movement Disorders Clinic since 2018, were retrospectively reviewed. Patients underwent neurological, biomechanical, and MSK evaluations, including 3D motion analysis, surface electromyography, and knee ultrasound. Therapeutic interventions, including botulinum neurotoxin (BoNT) injections, were assessed. Results: Seven patients demonstrated stiff knee gait subtypes, with all having ipsilateral and/or contralateral knee effusions or tendinopathies. Three patients who received MSK interventions (e.g., aspiration, corticosteroid injections) combined with BoNT therapy experienced significant symptom improvement. One patient with isolated foot dystonia displayed different biomechanical patterns without knee pathology. Conclusions: RD patients with stiff knee gait often exhibit knee pathology, most likely due to altered biomechanics and running history. Addressing both issues is essential for optimizing treatment outcomes, reducing pain, and improving function, especially since pain can trigger dystonia. Future research should determine the ideal sequence of interventions for RD patients with MSK issues to develop effective, personalized treatment algorithms. Full article

Aims: Intra-articular (IA) injection therapy, particularly IA hyaluronic acid (HA), is a common treatment for knee osteoarthritis, but it does have limitations. The injection of IA polynucleotide (PN) has emerged as an alternative, potentially offering superior clinical outcomes. This study investigates current practice patterns and the perceived effectiveness of PN among clinicians for treating knee osteoarthritis in the Republic of Korea. Methods: Based on a survey conducted among clinicians who use PN in clinical practice, we explored the current practices and assessed the perceived effectiveness of IA PN in treating knee osteoarthritis. Results: A total of 265 clinicians who used IA PN for knee osteoarthritis participated in the survey. Most clinicians (73.3%) used PN therapy for the treatment of chronic pain, with varying administration frequencies. In addition, 25.8% of clinicians used PN for the treatment of acute flare-ups. In cases of knee effusion, 55.5% of clinicians removed the effusion prior to administering PN. Clinicians rated PN as more effective than HA for both chronic pain and acute flare-ups, with higher scores for cushioning, anti-inflammatory effects, and delaying joint degeneration. The clinicians stated that patients expressed a higher satisfaction with IA PN compared with IA HA, noting improvement in joint smoothness, noise reduction, pain relief, and a reduction in heat sensation and swelling. Conclusions: The results of the present study highlight the extensive use and perceived benefits among clinicians of IA PN for knee osteoarthritis in the Republic of Korea. Further research is warranted to explore the effectiveness of PN in acute flare-ups and to validate these findings in broader populations. Full article

A 66-year-old woman presented with persistent knee effusion three months after undergoing a cemented medial uni-compartmental knee replacement. She was afebrile and able to walk with a stick. Physical examination revealed moderate effusion. Radiographs showed posteriorly extruded cement, while computed tomography confirmed the absence of implant loosening but was unable to adequately visualize the adjacent soft tissues due to metallic artifacts. Ultrasound identified posterior cement extrusion beyond the femoral component, causing a delamination tear of the posterior capsule and indentation on the medial gastrocnemius. Knee arthrocentesis yielded 60 mL of blood-stained fluid with unremarkable analysis, and the patient reported improvement following the procedure. To our knowledge, this is the first report to highlight the unique role of ultrasound in detailing the anatomy of extruded cement and its impact on adjacent soft tissues following knee replacement. We demonstrate the critical structures that should be evaluated and how ultrasound aids in managing this postoperative complication. Full article

Background: Native knee joint infections, while uncommon, present a serious condition predominantly instigated by bacteria such as Staphylococcus aureus. Without timely intervention, they can result in joint destruction or sepsis, with risk factors encompassing preexisting medical conditions and iatrogenic procedures. The diagnostic process includes a comprehensive patient history, clinical evaluation, laboratory testing, imaging studies, and microbiological investigations. Treatment typically involves joint aspiration and arthroscopy. This study aims to examine and establish correlations between diagnostic criteria and treatment modalities, enhancing the speed and specificity of future therapeutic strategies. Materials and methods: The present study is a retrospective cohort study conducted at a 1200-bed university clinic between 2007 and 2017, with an in-depth examination of patient details, symptoms, treatments, and outcomes. A scoring system was developed to classify the severity of knee joint impairment, categorizing patients on the basis of hospital stay duration, surgeries, and postoperative factors such as recurring symptoms, pain, and range of motion. Results: This study of 116 patients with knee joint infections revealed that clinical symptoms such as pain, swelling, and effusion are common but not definitive for diagnosis. Laboratory analysis revealed no significant differences in CRP or leukocyte counts between cultures positive or negative for pathogens. Hospital stay and disease severity are influenced by factors such as age, sex, presence of polyarthritis, neutrophil count, and type of pathogen, with higher weight and cortisone treatment associated with poorer outcomes. Conclusions: This study highlights the diagnostic challenges in native knee joint infections, revealing the need for comprehensive approaches given the nonspecificity of clinical symptoms and laboratory findings. This underscores the importance of advancing research through standardized methodologies and prospective studies to increase the accuracy of diagnosis and the effectiveness of treatment in this field. Full article

Background/Objectives: Genicular artery embolization (GAE) has demonstrated potential as a treatment for knee osteoarthritis by targeting inflammation and pain, although current evidence remains limited. This study used imaging biomarkers to objectively assess synovitis and possible ischemic complications following GAE. Methods: This was a prospective, single-center trial including participants with mild-to-moderate knee osteoarthritis. Ultrasound, contrast-enhanced (CE), and non-CE-MRI were performed two days before and one and six months after GAE. Ultrasound biomarkers included synovial hypertrophy, effusion, and Doppler activity. A combined effusion-synovitis score was assessed on non-CE-MRI, while CE-MRI allowed differentiation between synovium and effusion and was used to calculate whole-joint and local synovitis scores. The post-GAE MRIs were reviewed for ischemic complications. Results: Seventeen participants (aged 43–71) were treated. Significant reductions were observed in ultrasound-assessed synovial hypertrophy and Doppler activity, as well as in CE-MRI local and whole-joint synovitis scores. While reductions in effusion were noted in both ultrasound and MRI, these changes did not reach statistical significance. At one month, MRI revealed three cases of nonspecific osteonecrosis-like areas, which resolved completely by six months. Conclusions: This study demonstrated a reduction in synovitis and no permanent ischemic complication following GAE in knee osteoarthritis. Larger studies with longer follow-up are needed to confirm the long-term efficacy and safety of the procedure. Full article

Background/Objectives: Pigmented villonodular synovitis (PVNS) is a benign proliferation of synovial tissue that can cause joint damage. The hip, although less commonly affected than the knee, presents a challenging diagnosis and treatment, with magnetic resonance imaging (MRI) as the gold standard for detection. Surgical excision, arthroscopic or open, is the main treatment approach, but there is no consensus on the best strategy for the hip. The aim of this systematic review is to evaluate the clinical outcomes, complications, and revision rates associated with arthroscopic hip surgery for PVNS. Methods: A systematic review was performed following the PRISMA guidelines. Relevant studies were identified by searching four databases: PubMed, Scopus, Embase, and Medline. Selected articles were evaluated according to the criteria of levels of evidence (LoE). For retrospective studies, the Coleman Methodology Score (mCMS) was used. This systematic review was registered with the International Prospective Register of Systematic Reviews. Results: Six studies satisfied the criteria; these involved 77 patients (48% male, 52% female) with a mean age of 26.4 years and a mean follow-up of 54.3 months. MRI and biopsy confirmed the diagnoses, and arthroscopic synovectomy was the primary treatment. Success rates ranged from 80% to 100%, with a recurrence rate of 7.8%, 1.3% requiring revision surgery, and eight (10.4%) patients in three studies reporting conversion to THA. Complications included mild effusions and residual synovitis. All patients who underwent a subsequent total hip arthroplasty were affected by advanced osteoarthritis. Conclusions: Our systematic review reveals that the use of hip arthroscopy in diagnosing and treating PVNS has shown satisfactory results without increasing the risk of recurrence or complications and can return patients to their former activity levels, provided their preoperative osteochondral status is good and there is early management of PVNS of the hip joint. Full article

Knee effusion, a common and important indicator of joint diseases such as osteoarthritis, is typically more discernible on magnetic resonance imaging (MRI) scans compared to radiographs. However, the use of radiographs for the early detection of knee effusion remains promising due to their cost-effectiveness and accessibility. This multi-center prospective study collected a total of 1413 radiographs from four hospitals between February 2022 to March 2023, of which 1281 were analyzed after exclusions. To automatically detect knee effusion on radiographs, we utilized a state-of-the-art (SOTA) deep learning-based classification model with a novel preprocessing technique to optimize images for diagnosing knee effusion. The diagnostic performance of the proposed method was significantly higher than that of the baseline model, achieving an area under the receiver operating characteristic curve (AUC) of 0.892, accuracy of 0.803, sensitivity of 0.820, and specificity of 0.785. Moreover, the proposed method significantly outperformed two non-orthopedic physicians. Coupled with an explainable artificial intelligence method for visualization, this approach not only improved diagnostic performance but also interpretability, highlighting areas of effusion. These results demonstrate that the proposed method enables the early and accurate classification of knee effusions on radiographs, thereby reducing healthcare costs and improving patient outcomes through timely interventions. Full article