What are the symptoms of baker's cyst?

The fullness may feel like pressure behind the knee and can be more obvious when standing or straightening the leg. Some cysts cause little discomfort, while others produce knee pain, stiffness, or a feeling that the knee cannot bend fully. The swelling may change in size as fluid moves within the joint. A Baker's cyst often develops when a knee problem increases joint fluid, including knee osteoarthritis or a meniscus tear. These conditions can create symptoms in front of or around the knee as well as behind it. A lump behind the knee should be examined rather than identified by touch alone.

Avoid activities that clearly increase knee pain and use gentle movement that stays comfortable. Resting with the leg supported may ease pressure, while a clinician can advise whether cold therapy or other measures are suitable. Treatment usually considers the knee problem causing the fluid, not only the cyst. Depending on the findings, options may include physiotherapy or joint aspiration. Do not try to puncture or drain the swelling yourself.

Arrange an assessment for a new or persistent lump behind the knee, especially when it limits bending or walking. Seek urgent help if the calf suddenly becomes painful, swollen, warm, or tight, or if you develop breathlessness or chest pain. A cyst can rupture and cause fluid to track into the calf, but similar symptoms can also signal a blood clot. Severe knee pain, fever, redness, or inability to bear weight needs prompt review.

What could be causing the excess knee fluid? Do I need imaging? Would physiotherapy help my knee function? Is joint aspiration appropriate, and what symptoms should prompt urgent care?