Treatment of Posterior Knee Semimembranosus Bursitis
Begin with conservative management combining NSAIDs, activity modification, and quadriceps strengthening exercises, reserving corticosteroid injections for cases unresponsive to initial therapy after 6-8 weeks. 1, 2
Initial Conservative Management (First 6-8 Weeks)
Pharmacological Treatment
- Start with oral NSAIDs (e.g., naproxen 500 mg twice daily) as the cornerstone of initial treatment to reduce inflammation and pain 1, 2, 3
- For patients ≥75 years old, topical NSAIDs are strongly preferred due to superior safety profile 1, 2
- Acetaminophen (up to 4,000 mg/day) serves as an alternative first-line option for patients who cannot tolerate NSAIDs 1, 2
- For patients with gastrointestinal risk factors requiring oral NSAIDs, use COX-2 selective inhibitors or nonselective NSAIDs with proton-pump inhibitors 2
Non-Pharmacological Interventions
- Implement quadriceps strengthening exercises immediately—do not delay until pharmacological treatment fails 1, 2, 4
- Apply ice for 10-minute periods through a wet towel for short-term pain relief and reduction of swelling 5
- Modify activities to avoid repetitive knee flexion and kneeling that aggravate the bursa 6, 7
- Consider assistive devices such as walking sticks or insoles to reduce pressure on the affected area 1, 2
- Weight reduction is strongly recommended for overweight patients to decrease mechanical stress 1, 2
Common Pitfall
Avoid complete immobilization, as this leads to muscular atrophy and deconditioning; allow activities that do not worsen pain 5
Management of Inadequate Response (After 6-8 Weeks)
Corticosteroid Injection
- Intra-bursal corticosteroid injection (40-80 mg methylprednisolone acetate with 1% lidocaine) is indicated for acute exacerbations or cases unresponsive to conservative measures 2, 8
- Limit injections to every 3-4 months to avoid adverse effects 2
- Aspiration of bursal fluid may be performed prior to injection, particularly if effusion is present 6, 9
Important Caveat
Local corticosteroid injections near tendons remain controversial—while used for bursitis, the optimal dosage, technique, and intervals require careful consideration 5
Intensified Conservative Measures
- Continue initial pharmacological treatment 5, 2
- Intensify rehabilitation program with professional supervision 2
- Consider ultrasound and friction massage as adjunctive treatment modalities 7, 8
- Immobilization with a fixed-ankle walker-type device may be considered in particularly acute or refractory cases 5
Surgical Intervention (After 3-4 Failed Injections)
Surgical excision of the semimembranosus fibrous sheath is reserved for patients who fail to obtain relief after three or four corticosteroid injections 8
Surgical Approach Details
- Posterior medial oblique incision to reveal the semimembranosus osteofibrotic tunnel 8
- Excision of the fibrous sheath surrounding the tendon 8
- Best results occur when inflammation is localized only to the semimembranosus insertion area; fair or poor results occur when the knee joint or pes anserinus insertion is also involved 8
Critical Caveat
Surgery is not advised for young athletes due to the important function of the reflected head of the semimembranosus muscle 8
Diagnostic Considerations
Rule Out Septic Bursitis
- If infection is suspected based on acute onset, warmth, erythema, or systemic symptoms, perform bursal aspiration with Gram stain, culture, glucose measurement, and cell count before initiating treatment 9
- Ultrasonography can help distinguish bursitis from cellulitis 9
- Avoid aspiration in chronic microtraumatic bursitis due to risk of iatrogenic septic bursitis 9