Bursitis of the knee

A bursa is a fluid-filled sac that cushions and lubricates bones and tendons when they move. The body is comprised of over 150 bursae. Bursitis is an inflamed or swollen bursa. There are 14 bursae in the knee:- Suprapatellar bursa - between the lower femur and the quadriceps femoris- Prepatellar bursa - between the patella and the skin- Deep infrapatellar bursa - between the upper part of the tibia and the patellar ligament- Subcutaneous infrapatellar bursa - between the patellar ligament and skin- Pretibial bursa - between the tibial tuberosity and the skin- Lateral gastrocnemius bursa - between the lateral head of the gastrocnemius and the joint capsule- Fibular bursa - between the lateral collateral ligament and the tendon of the biceps femoris- Fibulopopliteal bursa - between the lateral collateral ligament and the tendons of the popliteus- Subpopliteal bursa - between the tendon of the popliteus and the lateral condyle of the femur- Medial gastrocnemius bursa - between the medial head of the gastrocnemius and the joint capsule- Pes anserinus bursa - between the medial collateral ligament and the tendons of the sartoris, gracilis, and semitendinosus- Bursa semimembranosa - between the medial collateral ligament and the tendon of the semimembranosus- There is one between the tendon of the semimembranosus and the head of the tibia- Occasionally there is a bursa between the tendons of the semimembranosus and semitendinosusBursitis in the knee can occur in any of the bursae, but the most common ones are: suprapatellar bursa, prepatellar bursa, infrapatellar bursa and pes anserinus bursa.