Arthritis is a general term for the inflammation of the joints; and consists of a group of disorders that involve joint damage. Usual symptoms often include swollen painful joints, a sense of localized warmth and restricted movements. It can also be a symptom of a more serious underlying disease, such as lupus erythematosus and Crohn's disease. Treatments usually include physical therapy, painkillers, steroids, antibiotics and/or other drugs that may be necessary to reverse the course of the disease and to prevent long-term damage.
As follows are the major types of arthritis:
Rheumatoid Arthritis (RA)
A very painful and disabling chronic disease in which the body's own immune system attack the joints, where it results in inflammation of surrounding cartilage, ligaments and bone, often leading to deformity. Not only are joints affected, other organs such as the lungs (fibrosis), kidneys (renal amyloiditis) and heart (atherosclerosis) are often affected as well.
Septic Arthritis
Also known as infectious arthritis, this is a condition characterized by the infection of a joint due to bacterial or more rarely by viral, mycobacterial, and fungal agents. Microorganisms may be introduced into the body through a skin lesion, injection or surgery; and carried via the blood stream into the joints. Other risk factors include old age (80 years and above), diabetes, a compromised immune system, and/or another condition affecting the joints, such as gout or rheumatoid arthritis.
Reactive Arthritis (ReA)
Formerly called Reiter's disease, this is an autoimmune disorder that occurs as a consequence of an infection in another body part. Its symptoms often include a combination of three seemingly unrelated conditions, e.g. arthritic inflammation of the major joints, eye inflammation (conjunctivitis or uveitis) and urethritis. Other names of ReA are arthritis urethritica, venereal arthritis and polyarteritis enterica.
Psoriatic Arthritis
Very similar to rheumatoid arthritis, it is a form of arthritis that affects around six to seven percent of people suffering from psoriasis, a chronic skin condition marked by itchy red scaly patches.
Felty Syndrome
A disorder characterized by the combination of rheumatoid arthritis, splenomegaly (enlargement of the spleen) and granulocytopenia (reduction in the number of granulocytes, a type of white blood cell). 
Juvenile Idiopathic Arthritis (JIA)
A type of arthritis of unknown cause that commonly affects children. Aside of the usual symptoms, children with JIA usually experience lethargy, poor appetite, decreased physical activity and/or an illness with flu-like symptoms.
Ankylosing Spondylitis (AS)
Also known as Bechterew syndrome and spondyloarthritis. An autoimmune disorder of possible hereditary predisposition, AS is a persistently painful degenerative inflammatory arthritis that leads ultimately to the fusion of the entire spine and sacroiliac joint.
Metabolic Arthritis
More commonly known as gout, a disease caused by uric acid buildup. Purines are generated by the breakdown of cells or through the intake of purine-rich foods like seafoods. Purine when metabolized produces uric acid that is normally excreted through the urine. But when uric acid crystals accumulate excessively in the blood stream, they are deposited on the articular cartilage of joints, tendons and neighboring tissues, and will produce an inflammatory response from them.
Calcium Pyrophosphate Deposition Disease (CPPD)
Also called chondrocalcinosis. CPPD is a rheumatologic disorder attributable to the accumulation of calcium pyrophosphate dihydrate crystals in the connective tissues. In short, it refers to the calcification of hyaline and/or fibrocartilage. Other symptoms aside from pain in affected joints include hyperparathyroidism (overproduction of parathyroid hormone), hemochromatosis (excessive absorption of dietary iron), hypophosphatemia (abnormally low phosphate in the blood) and renal osteodystrophy (defective mineralization due to kidney disease).
Osteoarthritis (OA)
The most common form of arthritis, also known by the term degenerative arthritis or degenerative joint disease. It involves inflammation in the joints due to abnormal wearing of the cartilage that cushions the joints, and reduction of synovial fluid that lubricates them. As the joint cartilage deteriorates, the patient feels pain upon weight bearing including standing and walking.
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