Treatment of Aseptic Bursitis in the Back of the Knee
For aseptic bursitis in the back of the knee (popliteal/Baker's cyst), begin with conservative management including rest, ice application for 10-minute periods through a wet towel, NSAIDs, and activity modification for 4-6 weeks before considering more invasive interventions. 1
Initial Conservative Management (First-Line Treatment)
- Rest and activity modification should be maintained for 4-6 weeks to eliminate pressure or repetitive motion on the affected bursa while preventing muscular atrophy 1
- Ice application for 10-minute periods through a wet towel provides pain relief 1
- NSAIDs serve as first-line pharmacologic therapy to control pain and inflammation 1, 2
- Immobilization with splinting may be used for comfort and to reduce inflammation in acute cases 3
When to Consider Aspiration
- Acute traumatic or hemorrhagic bursitis may benefit from aspiration, which can shorten the duration of symptoms 4
- Chronic microtraumatic bursitis should NOT be routinely aspirated due to the risk of iatrogenic septic bursitis 1, 4
- Aspiration is appropriate when there is significant fluid accumulation causing mechanical symptoms or when infection cannot be ruled out clinically 5
Corticosteroid Injection Considerations
- Corticosteroid injection may be considered after 4-6 weeks of failed conservative therapy 1
- Injection should combine corticosteroid with a local anesthetic (lidocaine) 5
- Ultrasound guidance can improve accuracy of bursal injection 1
- Never inject corticosteroids if infection is suspected, as this can worsen septic bursitis 1, 4
Critical Pitfall to Avoid
You must rule out septic bursitis before any corticosteroid injection. If there are signs of infection (fever, warmth, erythema, systemic symptoms), perform bursal aspiration with fluid analysis including Gram stain, culture, cell count, glucose measurement, and crystal analysis before proceeding with any treatment 4, 6
Follow-Up and Escalation
- Arrange follow-up within 1-2 weeks to assess response to treatment 3
- If symptoms persist despite 2-3 weeks of conservative management, consider referral to orthopedics or rheumatology 3, 1
- For refractory cases not responding to conservative treatment and corticosteroid injection, surgical excision of the bursa may be required 2, 5
Address Underlying Risk Factors
- Identify and modify repetitive motion patterns, obesity, and metabolic conditions (such as gout or rheumatoid arthritis) to prevent recurrence 1, 4
- For crystal-induced bursitis, recommend reduced meat and seafood intake, limited high-fructose foods, review of diuretic use, and reduced alcohol intake 1