A bursa is a fluid-filled structure that is present between the skin and tendon or tendon and bone. Bursae are generally are located around large joints such as the shoulder, knee, hip, and elbow. Knee bursae can be either those are around the patella and those that are elsewhere.
Knee Bursae Around The Patella
- Prepatellar bursa
- Superficial and deep infrapatellar bursae
- Suprapatellar bursa.
Other Knee bursae
- Pes anserine bursa
- Iliotibial bursa
- Tibial and fibular collateral ligament bursae
- Gastrocnemius-semimembranosus bursa
The main function of these knee bursae is to reduce friction between adjacent moving structures.
This bursa is located between the patella and the overlying subcutaneous tissue. Prolonged or repeated trauma as in kneeling can cause leads to inflammation and hemorrhagic bursitis which is presented as selling over the patella.
Infrapatellar bursae can be superficial or deep. The superficial infrapatellar bursa is located between the tibial tubercle. and the overlying skin.
The deep infrapatellar bursa is located between the posterior aspect of the patellar tendon and the tibia.
Superficial infrapatellar bursitis is also known as clergyman’s knee.
This bursa is between the quadriceps tendon and the femur.
Pes Anserine Bursa
The pes anserine bursa separates the pes anserine tendons [sartorius, gracilis, and semitendinosus] from tibial collateral ligament and the bony surface of the medial tibial condyle.
Anserine bursitis results from overuse.
Collateral Ligament Bursa
The medial and lateral bursae are located between the superficial and deep layers of the collateral ligament.
The iliotibial bursa is located between the distal part of the iliotibial band near its insertion on Gerdy tubercle and the adjacent tibial surface. Overuse and varus stress of the knee cause bursitis.
Gastrocnemius Semimembranosus Bursa
This bursa is located between the medial femoral condyle, semimembranosus tendon and the medial head of the gastrocnemius. Bursitis is also known as Baker cyst.