A "Baker's cyst" is an accumulation of synovial joint fluid that forms behind the knee.
A cyst may be formed by the connection of a normal bursa (a normal lubricating fluid sac) with the knee joint, which is more common in children. The condition can also be caused by a herniation of the knee joint capsule out into the back of the knee, which is more common in adults. This type of Baker's cyst is commonly associated with a tear in the meniscal cartilage of the knee. In older adults, this condition is frequently associated with degenerative arthritis of the knee.
There may be painful or painless swelling behind the knee during Baker's cysts. A large cyst may cause some discomfort or stiffness but generally has no symptoms. Occasionally, the cyst may rupture, causing pain, swelling, and bruising on the back of the knee and calf. Baker's cysts usually disappear spontaneously, but the time in which they do so is variable.
An X-ray image and MRI are done to confirm the existence of a Baker’s cyst and identify the reason for its occurrence (arthritis, meniscal tear etc.).
Often, no treatment is necessary for Baker's cysts and a doctor will observe the cyst over time. If the cyst is painful, treatment is usually aimed at correcting the underlying problem, such as arthritis or a meniscus tear. Removing a cyst is generally not done because the procedure may damage nearby blood vessels and nerves. Sometimes, a cyst can be drained if the fluid inside it has become solid and gel-like.
Taking all of this information into consideration, you can request painkillers while the diagnosis is confirmed by the orthopedist.