What Causes Joint Pain?

A joint is a place where two bones meet, connected by one or more ligaments. The ends of the bones are covered by cartilage, which allows the two bones to move easily. The joint is surrounded by a capsule that protects and supports it. The joint capsule is lined with a type of tissue called synovium, which produces synovial fluid, a clear substance that lubricates and nourishes the cartilage and bones inside the joint capsule.

Here are the three primary causes of joint pain:

1. Arthritis - Arthritis literally means inflammation of one or more joints. Arthritis causes pain, stiffness and swelling in the joints. Arthritis is classified as one of the rheumatic diseases. These are conditions that are different individual illnesses, with differing features, complications and treatments. They are similar in that they have a tendency to affect the joints, muscles, ligaments, cartilage and tendons, and many have the potential to affect other internal parts of the body. There are more than 100 different types of arthritis. Together, the many types of arthritis make up the most common chronic illness in the United States. The causes of arthritis depend on the form of arthritis. Causes include injury, metabolic abnormalities (such as gout), hereditary factors, infections and unclear reasons. The two most common types of arthritis are osteoarthritis and rheumatoid arthritis.

2. Tendonitis - Tendonitis is inflammation of a tendon. A tendon is fibrous tissue that connects a muscle to a bone. Tendons transmit the pull of the muscle to the bone to cause movement. Tendons can be small, like those found in the hand, or large, like the Achilles tendon in the heel. Tendonitis is most often the result of a repetitive injury in the affected area. Tendonitis occurs more often with age because tendons become less flexible and more prone to injury with age. People who perform activities that require repetitive motions or place stress on joints are at higher risk for tendonitis.

3. Bursitis - Bursitis is inflammation of a bursa. A bursa (the plural form is bursae) is a small, fluid-filled sac that acts as a cushion between a bone and other moving parts such as muscles or tendons. Bursae are found throughout the body. Bursitis occurs when a bursa becomes inflamed from injury, infection or due to an underlying rheumatic condition. Bursitis is commonly caused by overuse or direct trauma to a joint and it often occurs in the knee, shoulder or elbow. People who perform activities that require repetitive motions or place stress on joints are at higher risk for bursitis.