There are many causes of knee pain, such as overuse, obesity, arthritis or injury. However, there are two main causes of knee pain, they are arthritis and gout. If you are one of the millions of Americans suffering with knee pain or arthritis pain in the knee you may benefit from the many studies done on this subject. The three basic types of arthritis that may cause hip and knee pain: osteoarthritis and inflammatory arthritis (most commonly rheumatoid arthritis), and traumatic arthritis.

Autoimmune disorders such as rheumatoid arthritis or systemic lupus erythematosus can cause knee pain. In children, chronic knee pain may be the first sign of rheumatoid arthritis or simply "growing pains". Knee pain may result from trauma, overuse, internal derangement, osteoarthritis, or inflammatory arthritis. The differential diagnoses include inflammatory arthritis, bursitis or tendonitis, anterior knee pain and internal derangement.

Gout the another main reason for knee pains. Gout is a condition that causes sudden and severe attacks of pain, redness and swelling of joints. Gout is a condition has been well known for many centuries. Most often it affects a single joint in one episode, often the big toe. About 9 out of 10 affected individuals affected by gout are men over the age of 40. The peak age of attacks is 75 years, but it can occur in young individuals on rare occasions. Over one millions Americans have a gout attack each year.

Gout is due to accumulations of uric acid within the fluid of your joints. Uric acid is a waste product of many foods that we eat. In order to properly digest food, and rid our body of waste, we produce substances such as uric acid to transport waste material. Ultimately, uric acid is excreted via the kidneys in urine. However, when the transportation of uric acid is impaired, and uric acid accumulates in the blood stream, the condition called gout may result. The impairment of uric acid excretion is often due to a hereditary problem, but can also have other causes.

When the uric acid level becomes too high for an individual, painful attacks of gouty arthritis, or joint pain, can result. Other symptoms can include kidney stones, and, ultimately, kidney failure. It is interesting to note that the relationship between uric acid levels in the blood stream and gout is unclear. Some individuals with gout have normal or near normal blood levels of uric acid; other individuals have very high blood levels of uric acid with no symptoms of gout. It appears to be entirely dependent on the individual.

Some individuals have a hereditary condition making them more susceptible to gout; other risk factors also contribute to having a gouty attack. Among these are obesity and sudden weight gain, abnormal kidney function, excessive intake of alcohol (especially "binge" drinking), and certain types of cancer. Some medications, such as thiazide diuretics to control blood pressure, and foods that are rich in purines can lead to attacks. Purine-rich foods include organ meats (e.g. liver, kidney), herring, anchovies, and to an extent, all meat products.