1. Baker's Cyst By Ole Jakob Utkilen

2. Overview  Named after Dr. William Morrant Baker  Most common popliteal mass, with a prevalence of 4,5%  Synovial fluid collection in the Semimembranous Bursa  Found between medial head of the gastrocnemius muscle and the semimembranosus tendon  In adults it most commonly arises in association with arthritis or mennisical damage. Found in ~50% of RA patients  In children it usually appears without associated knee pathology and can remit spontaneously  Ranges in volume from 1-40 ml

3. Associated Conditions  Arthritis Osteoarthritis, RA, Juvenile RA, Gout, Reiter syndrome, Psoriasis, SLE  Internal derangement of the knee meniscal tears, anterior cruciate ligament tears, osteochondral fractures  Infection (septic arthritis, tuberculosis)  Chronic dialysis  Hemophilia  Hypothyroidism  Neuropathic osteoarthropathy (Charcot joint)  Sarcoidosis

4. Symptoms  Swelling  Pain  Knee Effusion  Thrombophlebitis  Clicking, Buckling or Locking of the knee  Leg edema  In case of cyst rupture there will be erythema, pain and swelling

7. Diagnosis  On inspection there will in most cases be a visible a mass in the popliteal fossa when the patients leg is extended.  On palpation the cyst can most easily be felt when the knee is slightly flexed.  Diagnosis is made by ultrasound, showing a cyst communicating with the joint space. Might also see calcifications or popliteal artery displacement.  Cyst will also show up on X-Ray and MRI  Aspiration can be used to determine that the cyst contains synovial fluid

10. Treatment  For asymptomatic or mildly symptomatic cyst, rest and elevation of the leg may be sufficient  Drainage and corticosteroid injection into the cyst  Surgical resection is reserved for severe cases, with recurrence being a common problem  Treat the underlying cause

11. Thank you for your attention