"A Baker cyst is swelling caused by fluid from the knee joint protruding to the back of the knee. The back of the knee is also referred to as the popliteal area of the knee. A Baker cyst is sometimes called a popliteal cyst. When an excess of knee joint fluid is compressed by the body weight between the bones of the knee joint, it can become trapped and separate from the joint to form the fluid-filled sac of a Baker cyst.

What causes a Baker cyst?

Baker cysts are not uncommon and can be caused by virtually any cause of joint swelling (arthritis). The excess joint fluid (synovial fluid) bulges to the back of the knee to form the Baker cyst. The most common type of arthritis associated with Baker cysts is osteoarthritis, also called degenerative arthritis. Baker cysts can occur in children with juvenile arthritis of the knee. Baker cysts also can result from cartilage tears (such as a torn meniscus), rheumatoid arthritis, and other knee problems

What are symptoms of a Baker cyst?

A Baker cyst may cause no symptoms or be associated with knee pain and/or tightness behind the knee, especially when the knee is extended or fully flexed. Baker cysts are usually visible as a bulge behind the knee that is particularly noticeable on standing and when compared to the opposite uninvolved knee. They are generally soft and minimally tender.

Physical therapy

Generally, patients with this condition should diligently follow the R.I.C.E. regime in the first 48 – 72 hours of injury. The R.I.C.E. regime can help to hasten healing and reduce pain and swelling and should comprise of rest from aggravating activities (crutches or a brace may be required), regular icing, the use of a compression bandage and keeping the leg elevated above the level of the heart. Anti-inflammatory medication may also help to hasten healing and recovery by reducing the pain and swelling associated with inflammation.

Patients with a Baker's cyst should perform pain free flexibility and strengthening exercises as part of their rehabilitation to ensure an optimal outcome.

One of the key components of rehabilitation is pain free strengthening of the quadriceps (vastus medialis obliquus muscle – VMO), hamstrings, gluteal and calf to improve the control of the knee joint with weight bearing activities. The treating physiotherapist can advise which exercises are most appropriate for the patient and when they should be commenced."

Reference and picture: http://www.ipcphysicaltherapy.com/Bakercyst.aspx