Knee bursae

Annotated image showing knee effusion, which can affect the bursae.

The knee joint is one of the most complex joints in the human body, and it contains several bursae that play a crucial role in its function. A bursa is a small fluid-filled sac that acts as a cushion between bones and soft tissues, reducing friction and allowing smooth movement.

Anatomy of Knee Bursae

The knee contains several important bursae, including:

• Prepatellar bursa: Located between the skin and the patella, this bursa allows the skin to move freely over the patella.
• Infrapatellar bursa: There are two infrapatellar bursae, the superficial and deep. The superficial infrapatellar bursa is located between the skin and the patellar tendon, while the deep infrapatellar bursa is located between the patellar tendon and the tibia.
• Suprapatellar bursa: This bursa is located above the patella, between the femur and the quadriceps tendon.
• Pes anserine bursa: Found on the medial side of the knee, this bursa is located between the pes anserinus tendons and the tibia.
• Semimembranosus bursa: Located on the posterior aspect of the knee, this bursa lies between the semimembranosus tendon and the medial head of the gastrocnemius muscle.

Function

The primary function of the knee bursae is to reduce friction and allow smooth movement of the knee joint. They facilitate the gliding of muscles and tendons over bony surfaces, which is essential for activities such as walking, running, and jumping.

Common Conditions

Bursitis is a common condition affecting the knee bursae. It is the inflammation of a bursa, often caused by repetitive motion or trauma. Symptoms include pain, swelling, and limited movement. The prepatellar bursa is commonly affected, leading to a condition known as "housemaid's knee."

Knee effusion, or "water on the knee," can also affect the bursae. It is characterized by an accumulation of excess fluid in or around the knee joint, which can lead to swelling and discomfort.

Related Pages

• Knee joint
• Bursitis
• Synovial fluid
• Patella
• Tendon