What is the treatment for knee effusion?

Treatment for Water on the Knee (Knee Effusion)

First-Line Treatment Approach

For acute knee effusion with pain, intra-articular corticosteroid injection is the most effective first-line treatment, providing significant pain relief within 1-2 weeks, particularly when inflammatory signs are present. 1, 2

When to Use Corticosteroid Injection

• Most effective when effusion is clinically present and accompanied by acute pain exacerbation 1, 2
• Provides relief for 1-24 weeks, though benefits may be relatively short-lived 1, 2
• One study demonstrated strong effect size of 1.27 for pain relief over 7 days compared to placebo 3
• Consider repeat injection if previous injection provided relief but symptoms recurred 1

Important Cautions for Corticosteroid Injection

• Monitor glucose levels for 1-3 days after injection in diabetic patients due to transient hyperglycemia risk 1
• Avoid overuse of the injected joint for 24 hours following injection 1
• Do not inject within 3 months prior to knee replacement surgery due to increased infection risk 1

Pharmacological Management for Mild-Moderate Cases

Step 1: Paracetamol (Acetaminophen)

• Start with oral paracetamol up to 4g/day for mild to moderate effusion with pain 1, 2
• Safe for long-term use with minimal side effects 3, 1
• Comparable efficacy to ibuprofen in short-term use 3

Step 2: NSAIDs (If Paracetamol Fails)

• Use oral or topical NSAIDs for patients unresponsive to paracetamol, especially with effusion present 3, 1, 2
• Demonstrated efficacy with effect size median of 0.49 3, 1
• More efficacious than paracetamol but with increased gastrointestinal side effects 3
• Topical NSAIDs are useful for patients unwilling or unable to take oral NSAIDs 3

Non-Pharmacological Management (Concurrent with Medications)

Implement these measures alongside pharmacological treatment:

• Regular patient education about the condition and self-management 1, 2
• Joint-specific exercises, especially quadriceps strengthening 1, 2
• Weight reduction if overweight 1, 2
• Physical supports such as walking sticks, insoles, or knee bracing 1, 2

Aspiration Considerations

When Aspiration is Indicated

• Perform aspiration for diagnostic purposes in effusions of unknown origin 4, 5
• Indicated for crystal-induced arthropathy, hemarthrosis, unexplained joint effusion, or symptomatic relief of large effusion 4
• Provides only temporary improvement (lasting approximately one week) due to early re-accumulation 5
• More beneficial in non-traumatic effusions for establishing diagnosis 5

Aspiration Technique

• Use lateral approach rather than medial - more likely to yield fluid in difficult cases 6
• Insert needle 1 cm above and 1 cm lateral to superior lateral aspect of patella at 45-degree angle 4
• Insert 1 to 1.5 inches, then aspirate aided by local compression 4

Contraindications to Aspiration

• Bacteremia 4
• Inaccessible joints 4
• Joint prosthesis 4
• Overlying soft tissue infection 4

Management of Refractory Cases

For persistent effusion despite conservative measures:

• Consider repeat intra-articular corticosteroid injection if previous injection provided relief 1
• Hyaluronic acid injections may be considered, though they have relatively small effect size 1, 2
• Joint lavage plus intra-articular steroid may provide additional benefit 2
• Joint replacement should be considered for refractory pain with disability and radiological deterioration 1, 2

Novel Treatment Option

Low-dose spironolactone 25 mg daily for 2 weeks showed 66% complete improvement in OA-related knee effusion in a 2016 prospective study, significantly outperforming ibuprofen (24% complete improvement) and cold compresses (28% complete improvement) 7. However, this is not yet incorporated into major guidelines and requires further validation.

Common Pitfalls to Avoid

• Do not rely solely on aspiration for treatment - it provides only temporary relief and effusion typically recurs within one week 5
• Do not assume medial approach is superior - lateral approach yields better results in difficult aspirations 6
• Do not use free-floating interpositional devices for treatment - high revision rates of 32-62% at 2-3 years 3
• Large effusions often recur and may require repeat aspiration 4