That lump in the hollow of the back of your knee may be a Baker’s cyst. This type of fluid-filled cyst was first described by William Morrant Baker who was a 19th century surgeon, hence the name Baker’s cyst. It is also known as a popliteal cyst. These cysts can develop when the knee is injured or when you have arthritis in your knee. The cyst forms as a result of over-production of synovial fluid. Usually, these protrusions are not serious, but they can cause problems if they get very large.
A Baker’s cyst forms a bump or lump on the back of the knee and may not present any symptoms. If it is small enough, it may be painless. Larger cysts can produce more noticeable symptoms:
- Pain – can be caused by inflammation and swelling
- Stiffness – arthritis can contribute to the stiffness caused by the cyst
- Limited range of motion – larger cysts can impede motion
If you have a bump on the back of your knee, you should seek medical attention to rule out other possibilities. There are other serious health conditions that could also present as a lump or bump in the hollow off the knee.
Diagnosis of Baker’s Cyst
A physical examination along with imaging tests can accurately determine if you have a Baker’s cyst or some other condition. Examination and testing can rule out other concerns such as blood clot, tumor or aneurysm, which may also present as a lump or bump on the back of the knee.
Ultrasound scans, X-ray and MRI are imaging tests used in diagnosis. These produce images of the internal structures of knee joint and can reveal if the protrusion is caused by synovial fluid. Once an accurate diagnosis has been made, your doctor will develop a treatment plan.
Smaller cysts may disappear without intervention. Treatment of the cause, such as a tear in the cartilage or arthritis, can also cause the cyst to go away. When this does not help, the cyst may need to be drained. This can be done with a needle. The needle is inserted into the cyst and the fluid is aspirated.
A corticosteroid injection may be required. This is used to reduce inflammation, which will also lead to pain relief. Though it can be effective, it does not always keep the cyst from forming again.
Physical therapy can help alleviate pain and swelling. Using the R.I.C.E. method is often helpful:
- Rest – ease up on activities involving use of the knee
- Ice – cold therapy can help reduce swelling
- Compression – wrapping the knee with a compression band, sleeve or using a brace
- Elevate – elevating the leg, especially at night, is helpful
Exercises to strengthen the muscles around the knee may also be advised. Gentle rage-of motion exercises are used to help keep the knee functioning.
Any protrusions at the back of the knee should be examined by a doctor. Contact Ortho Sport & Spine Physicians for more information and to schedule a consultation appointment.
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