Dancing with the Stars contestant Ralph Macchio had been out of rehearsals several times this past week due to pain caused by a ruptured Baker’s cyst behind his knee. The 49-year-old former Karate Kid :
“Have missed days of rehearsal this week. Had a ruptured cyst back of my knee causing acute pain. Hoping to be able to perform tonight!”
A former front-runner, Macchio did perform live on Monday night, but the pain plus lack of rehearsal time showed in his two dance performances. He landed in last place, and it remains in the voters' hands whether Macchio will survive this temporary setback.
A Baker’s cyst, sometimes called a popliteal cyst, is a buildup of synovial fluid that forms behind the knee. It is usually noticed as a swelling at the back of the knee and is due to an increased production of synovial fluid. When pressure builds up, fluid bulges into the back of the knee.
Baker’s cyst commonly occurs with:
- A tear in the meniscal cartilage of the knee
- Knee arthritis (in older adults)
- Rheumatoid arthritis
- Other knee problems
A large cyst may cause some discomfort or stiffness, but there are often no symptoms. There may be a painless or painful swelling behind the knee. The cyst may feel like a water-filled balloon. Sometimes, the cyst may rupture, causing pain, swelling, and bruising on the back of the knee and calf.
It is important to differentiate pain or swelling that is caused by a
Baker’s cyst from a deep venous thrombosis.
Physical exam will reveal a soft mass in the back of the knee. If the cyst is small, comparing the affected knee to the normal knee can be helpful. There may be limitation in range of motion caused by pain or by the size of the cyst. In some cases there will be signs and symptoms of a meniscal tear.
Meniscal injury may be suggested by performing an Apley's compression test, as demonstrated in this video:
Transillumination can show that the growth is fluid-filled. X-rays will not show the cyst or a meniscal tear, but they will show other problems that may be present, including arthritis. MRIs can help see the cyst and look for any meniscal injury.
Often no treatment is needed. The health care provider can watch the cyst over time. If the cyst is painful, the goal of treatment is to correct the problem, such as arthritis or a meniscus tear. The cyst usually is not removed because it can come back. The surgery also may damage nearby blood vessels and nerves. Sometimes, a cyst can be aspirated or, in rare cases, removed with surgery if it becomes very large or causes symptoms.
A Baker’s cyst will not cause any long-term harm, but it can be annoying and painful. The symptoms of Baker’s cysts usually come and go. Long-term disability is rare. Most people improve with time or arthroscopic surgery.
Source: Medline Plus