Knee bursae

Last revised by Dr Joachim Feger on 12 May 2021

Knee bursae are sacs surrounding the knee joint that are filled with synovial fluid. They facilitate movement and reduce friction where tendons or muscles pass over bony prominences. The knee bursae can be either communicating or non-communicating with the knee joint itself. 

There are four bursae anterior to the knee joint:

Two bursae are located laterally:

Two bursae are located medially: 

There are four bursae posterior to the knee joint:

  • between the capsule and medial head of gastrocnemius; communicates with the synovial cavity
  • semimembranosus bursa: between semimembranosus and the medial head of gastrocnemius; may communicate with the bursa under the medial head of the gastrocnemius and thereby the synovial cavity
  • lateral gastrocnemius bursa: between the capsule and lateral head of gastrocnemius; may communicate with the synovial cavity in some people
  • popliteus bursa: between popliteus tendon and posterior tibia and fibula; communicates with the synovial cavity 1

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Cases and figures

  • Figure 1: on lateral view
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