What are the potential complications of Baker cyst aspiration?
Aspiration of the semimembranosus-medial gastrocnemius bursa, or Baker cyst, is a frequently performed bursal aspiration under US guidance, with or without corticosteroid injection. The fluid collection lies between semimembranosus muscle and the medial head of the gastrocnemius muscle and may be simple or complicated. One potential complication of Baker cyst aspiration is inadvertent puncture of the adjacent popliteal artery or vein. This may be avoided by selecting a longitudinal plane or caudocranial approach as opposed to a transverse needle approach. The longitudinal approach is also beneficial in that the needle can be placed at the cranial margin of the Baker cyst and gradually withdrawn caudally as the Baker cyst decompresses.
It should be noted that Baker cysts frequently reoccur, and the patient should be made aware that aspiration often only provides temporary pain relief. Additionally, in ≈50% of patients, the Baker cyst communicates with the knee joint. Therefore, one should always check for a knee effusion prior to performing a Baker cyst aspiration. If present, the joint effusion should be aspirated prior to aspirating the Baker cyst in an attempt to avoid immediate reaccumulation of joint fluid within the Baker cyst.