Baker’s Cyst – Pictures, Symptoms, Treatment, Surgery

What is Baker’s Cyst?

Baker’s cyst, also known as popliteal cyst or bulge-knee, is a swelling of the synovial bursa located behind the knees (popliteal area). The swelling comes from synovial fluid in the knee joint that accumulates at the concave area behind the knee. The term ‘baker’s cyst’ was named for a British doctor named William Morrant Baker, the surgeon who first described it. It is a benign condition and not actually a “cyst” because it is not encapsulated and open communication with the synovial sac is preserved.

Baker’s cyst in adults usually develop due to excess weight that compresses the synovial fluid, leading to protrusion at the back of the knee. When the bulge grows, it becomes palpable.

Ruptured Baker’s Cyst

A baker’s cyst, when constantly irritated, can rupture. Constant irritation may include heavy lifting, running, climbing, squatting and kneeling despite the presence of baker’s cyst. The continued pressure on the knee joint and bursa causes the baker’s cyst to rupture. This causes protrusion of fluid down the leg between the gastrocnemius muscles (calf muscle) and leads to dissection. The leak of fluid down the inner leg causes symptoms such as:

1. Appearance of bruising on the calf and inner ankle.
2. Rapid swelling of the leg and calf muscle
3. Acute pain behind the knee and calf muscle
4. Redness in the calf

The symptoms of a ruptured baker’s cyst are similar to the symptoms of thrombophlebitis and the more serious deep vein thrombosis (DVT). These conditions cause thrombus formation on the veins that may be dislodged, causing life-threatening embolism, stroke, and myocardial infraction. For these reasons, ruptured baker’s cysts should be determined from thrombophlebitis and deep vein thrombosis for immediate management of said conditions. This is done through diagnostic tests such as ultrasounds and blood tests. Immediate medical treatment is required for deep vein thrombosis.

Baker’s cyst may also compress blood vessels and cause edema of the legs. Injury to blood vessels causes an inflammatory reaction and clot formation that may potentially lead to deep vein thrombosis. Although this is an infrequent occurrence, baker’s cyst should be managed early to prevent such complications.

The fluid from the ruptured cyst is often systematically absorbed by the body, but this does not mean that the baker’s cyst will go away. Usually, the swelling comes back and may lead to complication of the baker’s cyst again.

Ruptured baker’s cysts are usually treated with corticosteroid injections in the knee, rest and leg elevation. Arthropscopic surgery may also be done to permanently remove the baker’s cyst.

Causes of Baker’s Cyst

Baker’s cyst is caused primarily by swelling of the synovial joint that results from increase in synovial fluid due to certain factors. The swelling in turn increases pressure inside the bursa (the sac that contains the synovial fluid), causing the area to bulge at the back of the knee or popliteal area.

The most common reasons for swelling include:

Osteoarthritis

Osteoarthritis or degenerative arthritis causes irritation and compression of the synovial sac, causing it to bulge. This is the most common cause of baker’s cyst in adults.

Juvenile arthritis

Arthritis that occurs at a young age also causes swelling of the synovial bursa.

Cartilage Tears

Tears in the leg such as a torn meniscus (tears on the cartilage of the knee) and rheumatoid arthritis also may lead to baker’s cysts.

Symptoms of Baker’s Cyst

Baker’s cyst in some individuals is asymptomatic although some may also experience symptoms. The most common symptoms associated with baker’s cyst include the following:

1. Tightness behind the knees when the knees are fully flexed or extended
2. Knee pain, especially after movement or exercise
3. Visible bulge behind the knee, especially when standing
4. Soft and tender bulge, likened to a water-filled balloon
5. Swellings the size of a golf ball
6. Pressure that may extend into the calf muscle
7. Limited range of knee motion
8. Red glow on the area using transillumination (shine a light on the bulge with lights turned off)

Ruptured baker’s cyst can also cause significant pain, swelling, and bruising on the calf and inner ankle.

Diagnosis of Baker’s Cyst

Diagnosing baker’s cyst begins with physical examination of the knees, popliteal area, and calf muscles. Palpation is done to characterize the bulge and determine the presence of tenderness and pain.

Diagnostic tests are also employed, including:

Ultrasonography

Ultrasound of the popliteal area is the most common test for baker’s cyst to determine the extent of the swelling.

Magnetic Resonance Imaging

MRI can also reveal the presence of swelling in the popliteal area as well as any meniscal injury or tear.

Arthrogram

This involves the injection of dye into the knee, followed by imaging test.

Transillumination

Shining light on the bulge can show the presence of fluid, manifested by a red glow.

X-ray

X-rays are used to determine the presence of other problems such as arthritis.

When the bulge occurs with bizarre signs such as a rapid increase in size, sever pain during daytime and nighttime, fever, and difficulty of movement, the presence of tumors should be ruled out by doing more diagnostic tests.

Treatment of Baker’s Cyst

Asymptomatic baker’s cysts usually do not require any treatment. Baker’s cysts in children also do not require invasive managements. When symptoms occur, it’s better to manage the case to reduce uncomfortable feelings. Treatment for baker’s cyst involves medical and surgical treatment, natural remedies, and exercise.

Medical Treatment

1. Corticoseroids. Corticosteroids are injected into the area to reduce swelling and inflammation
2. Analgesics and anti-inflammatory medications. These are given to reduce inflammation and pain. Be sure to take the medication after meals to reduce gastrointestinal irritation.

Natural Treatment

1. Ice packs. Ice packs are placed over the area to reduce swelling and numb the area to reduce pain. Ice packs should be applied ten to fifteen minutes to achieve better results. This should be done during the acute phase of the condition.
2. Heat. Warm compresses over the area are helpful during chronic pain and bruising. This reduces pain by relaxing the structures on the area and also decreases the blood clot as a result of ruptured cysts.
3. Rest. Avoid strenuous activities that involve the knees and legs to prevent further injury. These activities may include running, squatting, climbing, kneeling, and lifting heavy objects.

Physiotherapy

1. Strengthening of the muscles. Exercises that focus on strengthening the calf and knee ligaments may help reduce symptoms and improve mobility. Stretching and other isometric and isotonic exercises are often suggested by a physiotherapist.
2. Bracing. Knee braces are used to support the joint and prevent further injury. In mild cases, a support using elastic bandage can be used.

Aspiration

Bakers’s cysts are usually resolved by aspirating the excess fluids in the area. Costicosteroids are usually injected after the procedure.

Surgery

Knee surgeries are often done with cases of other internal knee problems such as cartilage tears. The procedure involves arthroscopic surgery where the surgeon removes the swollen synovium. By removing this, the cyst formation is prevented from reoccurring. Arthroscopic surgery uses a special scope to visualize the internal aspects of the knee joint that aids the surgeon in doing the surgery.

Recovery from the procedure usually takes eight to twelve weeks. During this time, excessive motion of the knees should be prevented, although a simple range of motion exercises is essential in restoring the mobility of the knee joint.

Complications of Baker’s Cyst

Complications of baker’s cyst do not usually develop if treatments are implemented. Uncommon complications include:

1. Meniscal tears
2. Rupture of the baker’s cyst
3. Thrombophlebitis
4. Bruising
5. Chronic pain and swelling

Prognosis

Baker’s cysts do not cause significant harm if measures are taken. However, it can be painful and irritating. The symptoms of baker’s cyst are also easy to manage and most people recover after arthroscopic surgery. Long-term disability and complications are usually rare.

Since it is a benign condition, it usually does not spread or cause malignancy.