Which condition is characterized by the inflammation of a bursa?

Bursitis is characterized by the inflammation of a bursa, which is a small, fluid-filled sac located between bones and soft tissues, such as muscles and tendons. The primary role of a bursa is to reduce friction and cushion pressure points between the bones and the tendons or muscles around the joints. When a bursa becomes inflamed due to repetitive motion, injury, or underlying conditions, it leads to bursitis, which can result in pain, swelling, and restricted movement in the affected area.

In contrast, arthritis refers to a broad range of conditions that involve inflammation of the joints, but it does not specifically target bursae. Tendinitis involves inflammation of a tendon, while osteoporosis is a condition characterized by decreased bone density and increased risk of fractures, not inflammation. Thus, bursitis is the correct answer as it directly relates to the inflammation of a bursa.