The body has more than 140 bursae that help joints move smoothly while bending and straightening. If a bursa becomes inflamed, it is called bursitis.

  • Bursitis in a bursa located just under the skin occurs when the bursa is repeatedly irritated. Most cases occur at the front of the knee from kneeling and at the tip of the elbow from leaning on the elbows.
  • Bursitis in a deeper bursa may develop if the bursa is uncomfortably rubbed or pinched between a bone and another joint tissue, such as a tight tendon or muscle. This type of bursitis can occur in almost any joint, particularly the hips, shoulders, knee, and heel.
  • Septic bursitis is caused by an infection in a bursa and requires urgent treatment with antibiotics. It is most common in the knee and elbow.
  • Traumatic bursitis is caused by a one-time injury, such as a fall or high-impact collision. In this type of bursitis, the bursa temporarily fills with blood.