Inadequate anticoagulation and hyperuricemia cause knee pain after platelet-rich plasma injection: A retrospective study.

OBJECTIVES: Platelet-rich plasma treatment delays the need for total knee replacement in patients with knee osteoarthritis. However, its use and preparation remain controversial. The aim of this study was to investigate the relationship between anticoagulant use in the preparation of platelet-rich plasma and post-treatment pain in patients with knee osteoarthritis. Additionally, we explored the efficacy of platelet-rich plasma over medium- and long-term follow-up periods and identified other factors that may affect treatment outcomes. METHODS: In this retrospective study, 225 patients with knee osteoarthritis, who underwent knee platelet-rich plasma treatment from June 2021 to January 2022, were examined at three study centres. Patients were categorised, based on the type and amount of anticoagulant used during platelet-rich plasma preparation, into 4% sodium citrate (SC) 0.6 mL, 4% SC 1 mL, 4% SC 2 mL, heparin 0.1 mL, and heparin 0.2 mL groups. We analysed the patients' basic information, pain after treatment, and inflammatory markers (i.e., interleukin 6, tumour necrosis factor-α, and hypersensitive C-reactive protein) in the joint fluid via enzyme-linked immunosorbent assay and joint fluid crystallisation. Additionally, we assessed the patients' Western Ontario and McMaster University scores and minimal clinically significant differences after treatment. RESULTS: Patients in the 4% SC 0.6 mL and heparin 0.1 mL groups experienced less pain after platelet-rich plasma treatment than did patients in the high-dose anticoagulant group. The joint fluid of patients with pain in these groups had lower levels of inflammatory markers. Patients treated with SC had slightly better medium- and long-term therapeutic outcomes than did patients treated with heparin. Patients with poorly controlled hyperuricemia also experienced pain after platelet-rich plasma treatment. CONCLUSIONS: The results suggest that platelet-rich plasma prepared using high-dose anticoagulants or administered to patients with poorly controlled hyperuricaemia may lead to moderate-to-severe knee pain and joint effusion after joint puncture therapy. Platelet-rich plasma had a therapeutic effect on knee osteoarthritis; however, its efficacy gradually decreased over time. SC anticoagulant is more suitable for platelet-rich plasma preparation than is heparin. Further studies are needed to understand the safety and the various factors influencing platelet-rich plasma therapy.

Safety of CoronaVac and ChAdOx1 vaccines against SARS-CoV-2 in patients with rheumatoid arthritis: data from the Brazilian multicentric study safer.

BACKGROUND: Patients with immune-mediated rheumatic diseases (IMRDs) have been prioritized for COVID-19 vaccination to mitigate the infection severity risks. Patients with rheumatoid arthritis (RA) are at a high risk of severe COVID-19 outcomes, especially those under immunosuppression or with associated comorbidities. However, few studies have assessed the safety of the COVID-19 vaccine in patients with RA. OBJECTIVE: To evaluate the safety of vaccines against SARS-CoV-2 in patients with RA. METHODS: This data are from the study "Safety and Efficacy on COVID-19 Vaccine in Rheumatic Diseases," a Brazilian multicentric prospective phase IV study to evaluate COVID-19 vaccine in IMRDs in Brazil. Adverse events (AEs) in patients with RA of all centers were assessed after two doses of ChAdOx1 (Oxford/AstraZeneca) or CoronaVac (Sinovac/Butantan). Stratification of postvaccination AEs was performed using a diary, filled out daily and returned at the end of 28 days for each dose. RESULTS: A total of 188 patients with RA were include, 90% female. CoronaVac was used in 109 patients and ChAdOx1 in 79. Only mild AEs were observed, mainly after the first dose. The most common AEs after the first dose were pain at the injection (46,7%), headache (39,4%), arthralgia (39,4%), myalgia (30,5%) and fatigue (26,6%), and ChAdOx1 had a higher frequency of pain at the injection (66% vs 32 %, p < 0.001) arthralgia (62% vs 22%, p < 0.001) and myalgia (45% vs 20%, p < 0.001) compared to CoronaVac. The more common AEs after the second dose were pain at the injection (37%), arthralgia (31%), myalgia (23%), headache (21%) and fatigue (18%). Arthralgia (41,4% vs 25%, p = 0.02) and pain at injection (51,4% vs 27%, p = 0.001) were more common with ChAdOx1. No serious AEs were related. With Regard to RA activity level, no significant difference was observed between the three time periods for both COVID-19 vaccines. CONCLUSION: In the comparison between the two immunizers in patients with RA, local reactions and musculoskeletal symptoms were more frequent with ChAdOx1 than with CoronaVac, especially after the first dose. In summary, the AE occurred mainly after the first dose, and were mild, like previous data from others immunizing agents in patients with rheumatoid arthritis. Vaccination did not worsen the degree of disease activity.

Bisphosphonates show no association with preventing, slowing, or delaying radiographic changes and pain in hip osteoarthritis: A 4-year study in female adults using data from the Osteoarthritis Initiative Study.

OBJECTIVE: This study aimed to investigate the association of bisphosphonates with outcomes related to radiographic changes and pain in hip osteoarthritis (OA) over 4 years. METHODS: This study examined data from the Osteoarthritis Initiative (OAI), which included 4088 hips from 2057 participants. Bisphosphonate users were identified as those who reported usage at least three times, including at baseline and during the subsequent 1, 2, 3, and 4-year follow-up visits. Non-users were participants who did not use bisphosphonates in the 5 years preceding the baseline and at subsequent follow-up visits. Generalized estimating equations were performed to assess the association between bisphosphonate use and outcomes related to radiographic changes and pain in hip OA over a 4-year follow-up. RESULTS: The analysis revealed no statistically significant difference between bisphosphonate users and non-users concerning outcomes related to radiographic changes and pain in hip OA over 4 years. Specifically, the odds ratios for the incidence and transition of radiographic hip OA were 0.55 (95% Confidence Interval [CI]: 0.26 to 1.17) and 0.78 (95% CI: 0.47 to 1.28), respectively. Furthermore, the odds ratios for the development and resolution of frequent hip pain were 1.04 (95% CI: 0.76 to 1.42) and 0.99 (95% CI: 0.72 to 1.36), respectively. CONCLUSION: The findings from this longitudinal study do not suggest an association between bisphosphonate use and the prevention, slowing, or delay of development and transition of radiographic changes or pain in hip OA over a 4-year follow-up.

Clinical implications of persistent joint pain after gout flare.

OBJECTIVES: A subset of gout patients developed persistent joint pain after flares. Analysis of this clinical phenomenon may shed further light on the factors related to worsening gout and even provide clues to its pathogenesis. METHODS: We analyzed the clinical, laboratory, and ultrasound data of gout patients to explore the associations of these data with persistent joint pain after gout flares. RESULTS: A total of 1029 gout patients were included: 182 (17.7%) patients with persistent joint pain and 847 (82.3%) patients with nonpersistent joint pain. Patients with persistent joint pain had more total involved joints, more gout flares in the past year, and more joints with simultaneous gout flares (P<0.01). Among the ultrasound-detected lesions, patients with persistent joint pain had a higher incidence of tophus (36.4% vs. 21.1%) and bone erosion (18.6% vs. 8.6%) (P<0.05). Higher UA and lower TBil were found in patients with persistent joint pain (P<0.001). Hypertension (54.9% vs. 38.7%) and metabolic syndrome (58.8% vs. 46.4%) were both more frequent in patients with persistent joint pain (P<0.05). TBil was negatively correlated with the incidence of persistent joint pain (P<0.001, r=-0.190), UA values (P<0.001, r=-0.125), and metabolic syndrome scores (P<0.001, r=-0.192). A correlation curve was fitted using LOESS (locally weighted region). CONCLUSION: Persistent joint pain after gout flares is a marker of increased disease burden in gout. The significance of the level of total bilirubin for the exacerbation of gout deserves further study.

Synovial hemangioma presenting with chronic painful infrapatellar mass: a case report.

BACKGROUND: Synovial hemangiomas are rare benign vascular anomalies surrounded by a synovial lining and were first described by Bouchut in 1856. These neoplasms can develop in the intra-articular region, resulting in effusions and knee pain. However, their cause remains unknown. Prompt diagnosis and intervention are critical to prevent chondral damage. Histopathological examination is used to achieve the diagnosis, which is often delayed because of a lack of specific clinical signs. This report describes a unique case in which a painful infrapatellar mass was diagnosed as a synovial hemangioma. The absence of typical magnetic resonance imaging (MRI) findings highlights the importance of arthroscopic excision for diagnosis and symptom relief. CASE PRESENTATION: A 20-year-old woman presented with persistent anterior left knee pain that became exacerbated when she climbed stairs. Despite previous pain management and physical therapy, she developed a painful lump beneath her patella that worsened over time. She had also undergone arthrocentesis, but this did not relieve her pain. Physical examination revealed a palpable, immobile 5-cm mass along the patellar tendon with limited knee flexion and extension and normal ligament stability. T1-weighted fat-saturated MRI of the left knee with gadolinium-based contrast revealed a lobulated intra-articular mass in Hoffa's fat pad that resembled a soft tissue chondroma. A biopsy of the mass was performed to provide histopathological evidence, confirming the benign nature of the mass. The subsequent excisional arthroscopy, combined with incision enlargement for mass removal, confirmed the histopathologic diagnosis of synovial hemangioma based on the presence of numerous dilated blood vessels and venous proliferation within sections of the synovium. Recovery was complete, and no residual tumor was detected on follow-up MRI after 1 year. CONCLUSION: This case study emphasizes the importance of arthroscopic excision over open surgery for patients with synovial hemangioma. The minimally invasive nature of arthroscopy combined with the well-encapsulated nature and location of the mass facilitates complete resection.

[The painful knee in children]. / Das schmerzhafte kindliche Kniegelenk.

Knee pain is one of the most common reasons for medical consultation for musculoskeletal problems in the paediatric population. The aetiology is of very variable origin and necessitates a precise assessment. In addition to a thorough anamnesis, clinical and imaging examination methods, as well as laboratory diagnostics are of utmost importance to establish a proper diagnosis and an adequate treatment regimen. This chapter summarises the current diagnostic algorithm for dealing with knee pain in children and adolescents.

Long COVID Clusters of Symptoms Persist beyond Two Years after Infection: Insights from the CARDIO COVID 20-21 Registry.

Long COVID presents with diverse symptoms after COVID-19. Different clusters of symptoms have been reported; however, their persistence beyond 2 years after COVID-19 remains unclear. In this cohort study, we prospectively evaluated individuals with previous severe COVID-19 presenting with long COVID at a two-year follow-up. We characterized the included patients and performed a cluster analysis of symptoms through multiple correspondence analysis and hierarchical clustering. A total of 199 patients with long COVID were included. The median age was 58 years (48-69), 56% were male, and the median follow-up time since the COVID-19 diagnosis was 26 months (IQR: 25, 27). Three symptom clusters were identified: Cluster 1 is characterized by fatigue, myalgia/arthralgia, a low prevalence of symptoms, and a lack of specific symptoms; Cluster 2 is defined by a high prevalence of fatigue, myalgia/arthralgia, and cardiorespiratory symptoms, including palpitations, shortness of breath, cough, and chest pain; and Cluster 3 is demonstrated a high prevalence of ageusia, anosmia, fatigue, and cardiorespiratory symptoms. Our study reinforces the concept of symptom clustering in long COVID, providing evidence that these clusters may persist beyond two years after a COVID-19 diagnosis. This highlights the chronic and debilitating nature of long COVID and the importance of developing strategies to mitigate symptoms in these patients.

Photobiomodulation therapy for chronic knee pain in obese patients in pre-rehabilitation for bariatric surgery: randomised, placebo-controlled, double-blinded, clinical trial protocol.

INTRODUCTION: Obesity has become a worldwide public health problem and is directly linked to loss of quality of life, complications and comorbidities. One of them is chronic pain, especially in the knees, which increases significantly and proportionally with weight gain. In patients with severe obesity, with indication for bariatric surgery, the presence of chronic pain disables and often prevents their participation in a pre-surgical rehabilitation programme. As an analgesic therapy, photobiomodulation (PBM) has been studied with safety, efficacy, well-tolerated used and low costs. Thus, this study aims to evaluate the use of PBM for the treatment of chronic knee pain in obese patients undergoing a pre-surgical rehabilitation programme for bariatric surgery. METHODS AND ANALYSES: This is a double-blinded, randomised, placebo-controlled clinical, superiority, trial protocol. The PBM will be applied in bilateral knees and lumbar paraspinal points levels referring to the roots of innervation of the knee. The outcomes evaluated will be pain intensity, functionality, quality of life and clinical signs of neurological sensitization of chronic knee pain pathways. ETHICS AND DISSEMINATION: This protocol has already been approved by the Comitê de Ética em Pesquisa do Hospital das Clínicas da Universidade Federal de Goiás/EBSERH-Ethics Committee and it is following SPIRIT guidelines. The results will be statistically analysed and subsequently published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: Clinical Trials Platform (https://clinicaltrials.gov/) with the number NCT05816798.

Blood pressure is associated with knee pain severity in middle-aged and elderly individuals with or at risks for osteoarthritis: data from the Osteoarthritis Initiative.

BACKGROUND: Hypertension is a common comorbidity of osteoarthritis (OA). Joint pain is the main clinical manifestation of OA. Knowledge about the relationship between hypertension and OA pain is limited. This study aimed to investigate whether blood pressure parameters are associated with knee pain severity in individuals with or at risks for OA. METHODS: Our sample consisted of 2598 subjects (60.7% female, aged 45-79 years) collected from the Osteoarthritis Initiative. Blood pressure parameters included blood pressure stage, systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP). Radiographic evaluation using Kellgren-Lawrence system and pain severity evaluation using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), and Numeric Rating Scale (NRS) were performed for right knee. Linear regression was used to examine the relationship between blood pressure parameters and knee pain severity. RESULTS: For the overall sample, blood pressure stage, SBP, and PP were positively correlated with WOMAC and NRS pain scores when adjusting for age, sex, and body mass index (BMI) (p ≤ 0.024) and were inversely correlated with KOOS score (p ≤ 0.004). After further adjusting for all covariates, PP remained a positive correlation with WOMAC score (p = 0.037) while other associations between blood pressure parameters and pain scores did not reach the statistical significance. In female, higher blood pressure stage, SBP, and PP were significantly associated with increased WOMAC and NRS scores and decreased KOOS score after adjustments of age and BMI (p ≤ 0.018). When adjusting for all covariates, the correlations of PP with WOMAC, KOOS and NRS scores remained significant (p = 0.008-0.049). In male sample, SBP was positively correlated with WOMAC score when adjusting for age and BMI (p = 0.050), but other associations between blood pressure parameters and pain scores were not statistically significant. No significant correlation was observed in male when further adjusting for other covariates. CONCLUSIONS: Increased PP is a risk factor for knee pain and mainly affects females, which suggested that controlling PP may be beneficial in preventing or reducing knee pain in females with or at risks for OA.

Bilateral transient osteoporosis of the hip: a neglected cause of hip pain during pregnancy.

Transient osteoporosis of the hip (TOH) is an important but often neglected cause of hip pain, which can gradually lead to debilitating mobility and carries risks such as fracture or avascular necrosis. A 39-year-old woman presented to the Rheumatology department two weeks post-cesarean delivery, reporting the onset of left mechanical hip pain since the 33rd week of pregnancy. After delivery, similar complaints emerged on the right side. Hip X-ray showed a decrease in bone density in the left hip. Later, Magnetic Resonance Imaging revealed bilateral bone marrow edema in both proximal femurs. The diagnosis of TOH was established, and the patient was treated with conservative measures. Seven months later, she was asymptomatic. Pregnancy is a recognized risk factor for TOH, especially in the last trimester. It is an important differential diagnosis to consider in cases of hip pain in pregnant or newly breastfeeding women.

Diminished vibration perception and greater pressure pain sensitivity are associated with worse knee osteoarthritis outcomes across sex and race.

OBJECTIVE: To examine associations of vibration sensitivity and pressure pain sensitivity with knee osteoarthritis (OA) outcomes across sex and race, which may relate to known sex and race disparities in clinical outcomes. DESIGN: Data were from the 2013-2015 visit of the Johnston County Osteoarthritis Project. Exposures were vibration perception threshold (VPT) measured at the bilateral medial femoral condyle (MFC) and first metatarsophalangeal joint (MTP), and pressure pain threshold (PPT) measured at the bilateral upper trapezius. Outcomes were knee pain severity and presence of knee symptoms, radiographic knee OA, and symptomatic knee OA in each knee. Cross-sectional associations of the exposures with the outcomes were examined using logistic regression models, overall and separately by sex and race. RESULTS: In the VPT and PPT analyses, 851 and 862 participants (mean age 71 years, 68% female, 33% Black, body mass index 31 kg/m2) and 1585 and 1660 knees were included, respectively. Higher VPT (lower vibration sensitivity) at the MFC and first MTP joint was associated with all outcomes. Lower PPT (greater pressure pain sensitivity) was associated with greater knee pain severity. Associations of VPT and PPT with all outcomes were similar among females and males and Black and White individuals. CONCLUSIONS: Diminished vibration perception and greater pressure pain sensitivity were cross-sectionally associated with worse knee OA outcomes. Despite differences in VPT and PPT among females and males and Black and White adults, associations with knee OA outcomes did not differ by sex or race, suggesting neurophysiological differences do not relate to established disparities.

Leptospira spp. and Rickettsia spp. as pathogens with zoonotic potential causing acute undifferentiated febrile illness in a central-eastern region of Peru.

OBJETIVE: this study was to determine the relationship between acute febrile illness and bacterial pathogens with zoonotic potential that cause emerging and re-emerging diseases in a central-eastern region of Peru. RESULTS: Out of the 279 samples analyzed, 23 (8.2%) tested positive for infection by Rickettsia spp., while a total of 15 (5.4%) tested positive for Leptospira spp. Women had a higher frequency of infection by Rickettsia spp., with 13 cases (53.3%), while men had a higher frequency of infection by Leptospira spp., with 10 cases (66.7%). The most frequently reported general symptom was headache, with 100.0% (n = 23) of patients with Rickettsia (+) and 86.7% (n = 13) of patients with Leptospira (+) experiencing it. Arthralgia was the second most frequent symptom, reported by 95.6% (n = 22) and 60% (n = 9) of patients with Rickettsia (+) and Leptospira (+), respectively. Myalgia was reported by 91.3% (n = 21) and 66.7% (n = 10) of patients with Rickettsia (+) and Leptospira (+), respectively. Retroocular pain, low back pain, and skin rash were also present, but less frequently. Among the positives, no manifestation of bleeding was recorded, although only one positive case for Leptospira spp. presented a decrease in the number of platelets.

Iliotibial Band Origin Tendinopathy Is an Underrecognized Cause of Anterolateral Hip Pain: A Narrative Review and Clinical Commentary.

ABSTRACT: Hip pain is a common concern among athletes. With gluteal tendinopathy, femoroacetabular impingement, and osteoarthritis predominating sports medicine and musculoskeletal practices, less common etiologies may be overlooked. Complex pelvic anatomy and variable pain referral patterns may make identifying an accurate diagnosis challenging. Employing a systematic approach to evaluation and having a thorough understanding of hip region anatomy are essential. A potentially overlooked cause of anterolateral hip pain is iliotibial band origin tendinopathy. Patients often present with pain around the anterolateral hip and tenderness to palpation at the anterolateral iliac crest. While patients with iliotibial band origin tendinopathy usually respond to nonsurgical intervention, there is little literature to guide evaluation and treatment, highlighting a gap in the recognition of this condition. The purpose of this narrative review is to describe the anatomy of the proximal iliotibial band origin, outline the clinical diagnosis and imaging findings of ITBOT, and summarize current treatment options.

A 30-Year-Old Woman With Arthralgia, Progressive Dyspnea, and a Syncope Episode.

CASE PRESENTATION: A 30-year-old White woman with presumed rheumatoid arthritis accompanied by CT scan evidence of eosinophilic pneumonitis was referred to the ED by her rheumatologist for an investigation of the progression of dyspnea. Approximately 6 months before, the patient reported experiencing diffuse interphalangeal arthralgias (both proximal and distal) that affected the wrists, knees, and feet. These symptoms were accompanied by Modified Medical Research Council scale grade 2 dyspnea. During the initial assessment, the patient exhibited slight pallor and had no indications of inflammatory activity in the joints. Furthermore, the cardiovascular physical examination and the auto-antibody laboratory profile yielded normal results. However, a wrist ultrasound scan revealed evidence of active synovitis; a chest CT scan displayed multifocal bilateral ground-glass opacities and mild thickening of the interlobular septa. These findings suggested the presence of eosinophilic disease or an acute interstitial process related to collagen vascular disease. Consequently, the patient's treatment commenced with a weekly dose of methotrexate (10 mg). Despite the intervention, 2 months later, the patient returned, reporting persistent arthralgia and a worsening of dyspnea, now classified as Modified Medical Research Council scale grade 3. Subsequently, the rheumatologist referred her to the ED for further assessment. During the initial emergency evaluation, the patient experienced a syncope episode accompanied by orthostatic prodromal symptoms that included dizziness, nausea, and malaise.

Beyond the patella: Treatment of cam femoroacetabular impingement syndrome improves anterior knee pain.

OBJECTIVES: This study aimed to investigate if there is a relationship between cam femoroacetabular impingement syndrome (cam-FAIS) and chronic anterior knee pain (AKP). METHODS: This is a pilot retrospective review of 12 AKP patients with no structural anomalies in the patellofemoral joint and no skeletal malalignment in the lower limbs. All the patients were resistant to proper conservative treatment for AKP (AKP-R). Subsequently, these patients developed pain in the ipsilateral hip several months later, and upon evaluation, were diagnosed with cam-FAIS. Arthroscopic femoral osteoplasty and labral repair were performed and clinical follow-up of hip and knee pain and function (Kujala Score and Non-arthritic Hip Score -NAHS-) was carried out. RESULTS: All the patients showed improvement in the knee and hip pain scores with a statistically significant clinical difference in all of them at 69 months follow up (range: 18 to 115) except one patient without improvement in the groin VAS score post-operatively. Visual analogical scale (VAS) of knee pain improved from 6.3 (range: 5 to 8) to a postoperative 0.5 (range: 0 to 3.5), (p â€‹< â€‹0.001). The VAS of groin pain improved from 4.4 (range: 2 to 8) to a postoperative 0.9 (range: 0 to 3), (p â€‹< â€‹0.001). NAHS improved from a preoperative 67.9 (range: 28.7 to 100) to a postoperative 88 (range: 70 to 100), (p â€‹< â€‹0.015) and knee Kujala's score improved from a preoperative 48.7 (range: 22 to 71) to a postoperative 96 (range: 91 to 100), (p â€‹< â€‹0.001). CONCLUSION: This study's principal finding suggests an association between cam-FAIS and AKP-R in young patients who exhibit normal knee imaging and lower limbs skeletal alignment. Addressing cam-FAIS in these cases leads to resolution of both groin and knee pain, resulting in improved functional outcomes for both joints. STUDY DESIGN: Retrospective cohort series with a single contemporaneous long-term follow-up. LEVEL OF EVIDENCE: IV.

Krill Oil for Knee Osteoarthritis: A Randomized Clinical Trial.

Importance: Knee osteoarthritis is disabling, with few effective treatments. Preliminary evidence suggested that krill oil supplementation improved knee pain, but effects on knee osteoarthritis remain unclear. Objective: To evaluate efficacy of krill oil supplementation, compared with placebo, on knee pain in people with knee osteoarthritis who have significant knee pain and effusion-synovitis. Design, Setting, and Participants: Multicenter, randomized, double-blind, placebo-controlled clinical trial in 5 Australian cities. Participants with clinical knee osteoarthritis, significant knee pain, and effusion-synovitis on magnetic resonance imaging were enrolled from December 2016 to June 2019; final follow-up occurred on February 7, 2020. Interventions: Participants were randomized to 2 g/d of krill oil (n = 130) or matching placebo (n = 132) for 24 weeks. Main Outcomes and Measures: The primary outcome was change in knee pain as assessed by visual analog scale (range, 0-100; 0 indicating least pain; minimum clinically important improvement = 15) over 24 weeks. Results: Of 262 participants randomized (mean age, 61.6 [SD, 9.6] years; 53% women), 222 (85%) completed the trial. Krill oil did not improve knee pain compared with placebo (mean change in VAS score, -19.9 [krill oil] vs -20.2 [placebo]; between-group mean difference, -0.3; 95% CI, -6.9 to 6.4) over 24 weeks. One or more adverse events was reported by 51% in the krill oil group (67/130) and by 54% in the placebo group (71/132). The most common adverse events were musculoskeletal and connective tissue disorders, which occurred 32 times in the krill oil group and 42 times in the placebo group, including knee pain (n = 10 with krill oil; n = 9 with placebo), lower extremity pain (n = 1 with krill oil; n = 5 with placebo), and hip pain (n = 3 with krill oil; n = 2 with placebo). Conclusions and Relevance: Among people with knee osteoarthritis who have significant knee pain and effusion-synovitis on magnetic resonance imaging, 2 g/d of daily krill oil supplementation did not improve knee pain over 24 weeks compared with placebo. These findings do not support krill oil for treating knee pain in this population. Trial Registration: Australian New Zealand Clinical Trials Registry Identifier: ACTRN12616000726459; Universal Trial Number: U1111-1181-7087.