What can pain behind the knee be a symptom of?

Pain behind the knee may be caused by a popliteal cyst, or baker's cyst, which is a painful lump created by a pocket of synovial fluid behind the knee, according to Healthline and WebMD. Baker's cysts are most commonly experienced in individuals suffering from rheumatoid arthritis or osteoarthritis.

Synovial fluid lubricates the joint in the knee, but this cyst occurs when excess amounts of the fluid moves into a sac behind the knee, explains WebMD. Along with a painful, tight sensation behind the knee, other symptoms may include swelling in the same area and pain that extends into the upper calf. In severe cases, the cyst breaks open underneath the skin, sending the fluid to other parts of the leg. Symptoms of this may include additional swelling and redness in those areas.

Less serious cases of baker's cysts typically heal on their own, notes WebMD. If the pain is severe or the cause is arthritis, the physician that diagnoses the patient may drain the fluid and administer a steroid injection to reduce swelling. Severe cases may require surgery. To treat a baker's cyst at home, patients are advised to rest the knee, use crutches, and take ibuprofen or similar medications to manage pain and swelling.