What are the symptoms and management options for knee effusion in an adult patient with a history of rheumatoid arthritis (RA)?

Symptoms of Knee Effusion in Rheumatoid Arthritis

In an adult patient with rheumatoid arthritis presenting with knee effusion, the primary symptoms include joint swelling, pain, stiffness (particularly morning stiffness lasting at least 1 hour), and decreased range of motion, with tenderness to palpation being a hallmark clinical feature. 1

Clinical Presentation

Cardinal Symptoms

• Joint swelling is the most apparent clinical sign, presenting as fusiform soft tissue swelling around the knee that is tender on palpation 2, 1
• Pain accompanies the effusion and is characteristically worse in the morning, improving throughout the day 1
• Morning stiffness lasting at least 1 hour before maximal improvement is a typical and defining feature of RA-related knee effusion 1
• Severe motion impairment occurs early, even before radiologic evidence of bone damage appears 1

Associated Features

• Warmth over the affected joint may be present due to inflammatory synovitis 2
• Systemic symptoms including fatigue, malaise, weight loss, and low-grade fever can accompany articular manifestations 1
• The knee is a preferential site for RA involvement, often presenting with symmetric bilateral disease 2

Diagnostic Evaluation

Immediate Assessment Required

• Perform arthrocentesis to obtain synovial fluid for cell count, Gram stain, culture, and crystal analysis to definitively rule out septic arthritis, gout, or pseudogout 3
• Obtain standing AP, lateral, and Merchant view radiographs to evaluate for fracture, osteoarthritis severity, loose bodies, or structural abnormalities 3

Imaging Findings

• Early abnormalities consist of synovial proliferation, soft tissue swelling, and juxta-articular osteoporosis 2
• MRI is more sensitive than clinical examination for detecting effusions and can differentiate synovial fluid from inflammatory pannus 4, 2
• Ultrasound is recommended to diagnose soft tissue involvement and can show synovial thickening even in early disease 2, 1

Management Approach

First-Line Treatment

• Intra-articular corticosteroid injection is the first-line treatment for non-septic knee effusion with pain in RA patients, providing significant relief within 1-2 weeks 3
• Triamcinolone hexacetonide (20 mg) demonstrates superior efficacy with earlier onset and longer duration of therapeutic effects compared to other agents 5
• Corticosteroid injections are particularly effective when effusion is present and provide benefit for 1-4 weeks, though effects may diminish by 12-24 weeks 3

Systemic DMARD Therapy

• Start effective treatment immediately with DMARDs to reduce disability, using methotrexate as the initial treatment at effective doses (oral or subcutaneous) with folic acid 6
• Rapidly escalate treatment with various DMARDs if methotrexate alone is not effective in controlling RA 6
• Aim for a treat-to-target strategy with a goal of low disease activity or remission by frequently monitoring disease activity 6

Adjunctive Measures

• Implement quadriceps strengthening exercises and patient education immediately alongside pharmacological treatment 3
• Oral NSAIDs demonstrate efficacy and are particularly effective with inflammatory effusions 3
• Acetaminophen up to 4g/day can be used as initial analgesic for mild-to-moderate pain 3

Important Clinical Caveats

• Do not administer intra-articular steroids unless an appropriate diagnosis has been made and contraindications (particularly septic arthritis) have been ruled out 7
• Aseptic technique must always be undertaken when performing intra-articular therapy 7
• Avoid overuse of the injected joint for 24 hours following intra-articular therapy; however, immobilization is discouraged 7
• The shared decision to reinject a joint should consider benefits from previous injections and other individualized factors including systemic treatment and comorbidities 7