What is the best treatment approach for a patient with a small joint effusion in the knee, considering potential underlying conditions such as osteoarthritis (Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)) or rheumatoid arthritis (Disease-Modifying Antirheumatic Drugs (DMARDs))?

Treatment of Small Knee Joint Effusion

First-Line Treatment: Intra-articular Corticosteroid Injection

For small knee joint effusion with pain, especially when accompanied by inflammatory signs, intra-articular injection of long-acting corticosteroid is the first-line treatment, providing significant pain relief within 1-2 weeks. 1, 2

• Corticosteroid injection is more effective when effusion is present, though benefits are relatively short-lived (1-24 weeks) 3, 1, 2
• The injection provides significant improvement in pain and function compared to placebo at 1 and 4 weeks, though this effect diminishes by 12-24 weeks 3
• This approach is indicated specifically for acute exacerbation of knee pain accompanied by effusion 3

Important Caveats for Corticosteroid Injection:

• Monitor glucose levels for 1-3 days after injection in diabetic patients due to potential transient hyperglycemia 2
• Avoid overuse of the injected joint for 24 hours following injection 2
• Avoid injection within 3 months prior to knee replacement surgery due to increased infection risk 2

Oral Analgesic Therapy

Initial Oral Therapy: Paracetamol (Acetaminophen)

• Start with paracetamol up to 4g/day as the initial oral analgesic for mild to moderate effusion with pain 1, 2
• Paracetamol is safe for long-term use with minimal side effects and no common contraindications, including in elderly patients 3
• Evidence shows paracetamol is effective with an effect size comparable to ibuprofen in short-term use 3

Second-Line Oral Therapy: NSAIDs

• NSAIDs (oral or topical) should be used for patients unresponsive to paracetamol, especially with effusion 3, 1, 2
• NSAIDs demonstrate efficacy with median effect size of 0.49 compared to placebo 3, 1, 2
• Naproxen provides greater pain reduction than paracetamol (effect size 0.32-0.45) but with increased gastrointestinal side effects 3
• Topical NSAIDs are useful for patients unwilling or unable to take oral NSAIDs, with topical diclofenac showing positive effect size of 0.91 3

NSAID Safety Considerations:

• NSAIDs may increase risk of heart attack or stroke, especially with longer use and in patients with heart disease 4
• NSAIDs can cause ulcers and bleeding in stomach and intestines at any time during treatment, with increased risk in patients taking corticosteroids, anticoagulants, or with longer use, smoking, alcohol consumption, older age, or poor health 4
• Never use NSAIDs right before or after coronary artery bypass graft surgery 4

Non-Pharmacological Management (Concurrent with Pharmacological Treatment)

Non-pharmacological treatments must be implemented concurrently with pharmacological approaches, not as alternatives 3, 1, 2

• Regular patient education about the condition and management 1, 2
• Exercises directed toward quadriceps strengthening and preserving normal knee mobility are strongly recommended 3, 1
• Weight reduction if the patient is overweight 3, 1, 2
• Physical supports such as walking sticks, insoles, or knee bracing 1, 2

Evidence for Combined Approach:

• Home exercise programs, physiotherapy, and education offer additional benefit when used in addition to analgesic regimens 3
• Wedged insoles combined with oral indomethacin showed significant improvement compared to indomethacin alone (effect size for pain = 0.5) 3

Management of Refractory Cases

Repeat Corticosteroid Injection

• For persistent effusion and pain despite conservative measures, repeat intra-articular corticosteroid injection may be considered if previous injection provided relief 2

Hyaluronic Acid Injections

• Hyaluronic acid may be considered for refractory cases, though it has a relatively small effect size 1, 2
• Evidence supports efficacy for both pain reduction and functional improvement, with pain relief lasting several months rather than weeks 3
• Requires a course of 3-5 weekly injections with associated logistical and cost considerations 3
• Slower onset of action compared to corticosteroids 3
• Patients over 60 years with significant functional impairment respond better 3
• Patients with less severe structural disease do better, while those with effusion at baseline do worse 3

Joint Lavage Plus Corticosteroid

• Joint lavage combined with intra-articular steroid may provide additional benefit, most marked in the first month 3, 1

Surgical Intervention

• Joint replacement should be considered for refractory pain with disability and radiological deterioration 3, 1, 2

Special Considerations for Underlying Conditions

If Osteoarthritis is the Underlying Cause:

• Follow the treatment algorithm above, starting with corticosteroid injection for effusion 3
• Treatment should account for age, comorbidity, and presence of inflammation 3

If Rheumatoid Arthritis is Suspected:

• DMARDs (Disease-Modifying Antirheumatic Drugs) are first-line therapy for all newly diagnosed cases of rheumatoid arthritis 5
• Methotrexate is the primary DMARD, indicated for severe, active rheumatoid arthritis in patients with insufficient response to or intolerance of NSAIDs 6, 5
• Early aggressive therapy with DMARDs is favored, including early referral to a rheumatologist 5
• NSAIDs and low-dose steroids may be continued with DMARDs, though possibility of increased toxicity with concomitant NSAID use has not been fully explored 6
• Methotrexate effects on articular swelling and tenderness can be seen as early as 3-6 weeks, though it does not induce remission or prevent bone erosions 6

Diagnostic Aspiration Considerations

• Aspiration provides only temporary improvement (lasting first week only) due to early re-accumulation of effusion 7
• Aspiration is suggested for effusions of unknown origin to establish diagnosis and provide immediate clinical relief 7
• Aspiration aids in earlier diagnosis establishment in non-traumatic effusion cases 7
• Among indications for arthrocentesis: crystal-induced arthropathy, hemarthrosis, unexplained joint effusion, and symptomatic relief of large effusion 8
• Contraindications include bacteremia, inaccessible joints, joint prosthesis, and overlying soft tissue infection 8