Baker’s Cyst Aspiration and Injection

• Purpose – Relieve pain and swelling behind the knee, the feeling of tightness or fullness that worsens when standing, and alleviate the difficulty of bending at the knee.

• Overview – Cyst aspiration is the removal of excess fluid, and a steroid is often injected to fill the cyst and reduce the chance of it returning.  Baker’s cysts are membrane-lined, fluid-filled lumps that develop behind the knee. Common causes for Baker’s cysts include arthritis, torn cartilage in the knee,  and advanced osteoarthritis. This procedure may be done with image guidance.

• Before the procedure – No special preparation is needed for this procedure.

• Details – The procedure begins with the application of an anesthetic on top of the cyst. The cyst is punctured with a needle in order to begin aspiration. Then, using a syringe, the fluid is drained from the base of the cyst. A steroid is often injected into the empty cyst in order to reduce inflammation.

• After the procedure – Numbness should only last a few hours until the anesthetic wears off. Once the anesthetic wears off, there may be mild discomfort that lasts for a couple of days.  There is a chance of the cyst returning. Possible side effects include bruising, swelling, or risk of infection at the injection site.