The term arthritis refers to pain, swelling and stiffness of joints. Pain is due to the irritation of nerve fibers in the inflamed joints. Swelling is due to either increased fluid in the joints or due to hypertrophy of the synovial membrane which is covering the joint . Stiffness refers to the discomfort in moving joints following a period of inactivity. This is classically described as increase in difficulty in moving joints or making a fist soon after getting up from the bed. This is relieved with activity and aggravated by rest. There are close to 230 movable joints in the body . Arthritis can affect any of these parts resulting in pain in the corresponding area like knee pain, back pain or neck pain.
It is very important to remember that more than 150 disorders can present with pain in the joints. So joint pain is not a disease but a symptom. We can explain this with a commoner example. If you go to a doctor with fever, it can be due to mild viral infection to life threatening diseases like blood cancers or malaria. To determine what disease you have doctor examines you and does a series of tests. Similarly arthritis also can be due to very simple disease like viral infection to life threatening diseases like SLE. Joint pain is one of the ways body tells you that something is wrong somewhere and it is the duty of a physician to find out what disease the patient is suffering from and start him on correct treatment.
As I have said earlier, arthritis may be manifestation of an internal disease. Some of these diseases can affect internal organs like Lungs, kidney or heart. So it is absolutely essential that you get a proper check up and get correct treatment.