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Baker's (Popliteal) Cyst
ℹ️ About
🦵 A Baker’s cyst (popliteal cyst) forms when fluid leaks from a knee effusion into the gastrocnemius-semimembranosus bursa, creating a swollen sac behind the knee.
🧬 Aetiology
Degenerative changes in the knee joint leading to effusion & leakage.
⚡ OA (osteoarthritis) and RA (rheumatoid arthritis).
Meniscal cartilage degeneration.
Anterior cruciate ligament (ACL) injury.
👩⚕️ Clinical
Typically seen in middle-aged and older patients.
Swelling, tightness, stiffness, or discomfort in the popliteal fossa.
Cyst located in the sub-gastrocnemius bursa.
Large cysts → bulging mass and restricted movement.
❗ A ruptured cyst can mimic a DVT → acute calf pain, swelling, erythema.
🔎 Investigations
🖥️ Ultrasound: First-line, distinguishes cyst from DVT or aneurysm.
🧊 Conservative: Rest, ice, elevation, NSAIDs for pain/swelling.
💉 Aspiration + steroid injection: For recurrent or symptomatic cysts.
🧘 Physiotherapy: Strengthening/quadriceps exercises to improve joint function.
⏳ Spontaneous resolution often occurs within 6–12 months.
🔪 Surgery (arthroscopy ± cyst excision): Considered if cyst persists, is very large, or associated with intra-articular pathology (e.g. meniscal tear).