A baker’s cyst is a benign swelling behind the knee. A baker’s cyst is also known as popliteal cyst which lies posterior to the medial femoral epicondyle. The cyst is connected to the knee joint through a valvular opening. Knee effusion from intra-articular pathology allows the fluid to go through the valve to the cyst in one direction. The cyst is located between the semi membranous and medial gastrocnemius muscles.
The patient usually has swelling behind the knee, with pain, fullness and tenderness. A baker’s cyst is easier to see with the knee fully extended. Diagnosis is confirmed by MRI that will show the associated intra-articular pathology. Ultrasound is helpful as well. These tests are important especially if the cyst is found to be outside of its typical position.
The two most common causes of baker’s cyst are knee arthritis and meniscal tear. Treatment of painful large cysts may include ice, compressions wrap, corticosteroid medication, strengthening exercises and aspiration of the cyst. Recurrence of baker’s cyst is common if the intra-articular pathology continues. The best treatment is arthroscopy and debridement of the intra-articular pathology.
The cyst may burst causing calf pain and swelling. Rule out deep venous thrombosis or thrombophlebitis.
Popliteal cysts in children is a common soft tissue mass at the back of the knee. It occurs more in boys and it is asymptomatic. It is not a tumor. It is treated by observation, no surgery needed. It is not associated with a meniscal tear.