Joint diseases describe those illnesses that affect the joints, which are where two bones come together. Joints consist of bones, cartilage, muscles and ligaments and not only hold the skeleton together, but also allow for movement. A thin layer of soft tissue lines the joints, called the synovium, and produces synovial fluid, which acts as a shock absorber and protects the joints from damage. The different types of joint diseases are classified based on the cause of the disease.
Autoimmune Diseases
Autoimmune diseases describe a group of diseases that occur when the body’s immune system malfunctions. The immune system, which consists of different types of white blood cells, protects the body from foreign invaders such as bacteria and viruses. In the presence of a foreign invader, the cells of the immune system produce antibodies, a specific kind of protein, and secrete chemicals to trigger inflammation. Sometimes the immune cells fail to distinguish between a foreign invader and healthy cells. This causes the immune system to attack healthy tissue, resulting in an autoimmune disease.
Rheumatoid arthritis, classified as an autoimmune disease, occurs when the immune cells attack the synovial cells and cause inflammation of the lining of the joints. Rheumatoid arthritis, which affects approximately 1.3 million Americans, causes joint damage that progressively worsens over time, according to the Arthritis Foundation. Lupus, another autoimmune disease, damages many parts of the body including the joints. Approximately 90 percent of patients develop inflammation of the joints resulting in joint pain, swelling and redness, according to the University of Maryland Medical Center.
Infectious Diseases
Infectious diseases, including both viral infections and bacterial infections, can cause joint disease. When the virus or bacteria enters the body, the immune system goes to work to eliminate it. When the body fails and treatment is delayed, the foreign invader can travel to the joints and result in inflammation.
Lyme disease, a bacterial infection caused by the bacterium Borrelia burgdorferi, transmits to humans through a bite by an infected tick. The disease typically begins as a circular rash, but as the bacteria travel through the bloodstream, additional symptoms occur. Approximately 60 percent of patients with Lyme disease develop arthritis-like symptoms, including joint pain and stiffness, according to the Centers for Disease Control and Prevention. Other infectious joint diseases include rheumatic fever, caused by group A Streptococcus bacteria, rubella and gonorrhea.
Arthritis Diseases
Arthritis describes a group of over 100 different types of medical conditions that affect the joints, according to the Arthritis Foundation. Arthritis conditions cause inflammation of the joints that damage the cartilage and lead to joint weakness and instability, joint deformity and loss of movement. The joint diseases classified as arthritis affect 46 million adults and 300,000 children in the United States alone, according to the Arthritis Foundation. Types of arthritis include osteoarthritis, the most common type, juvenile arthritis and rheumatoid arthritis. Other arthritis joint diseases include Ankylosing spondylitis, fibromyalgia and Gaucher’s disease.
