Osteoarthritis the most common arthritis in the world wide is an incurable disease. But currently available treatment may slow the progress of the disease, relive the symptoms to some extent, so that the affected person is capable of leading a normal life to some extent.
Available treatment options include drugs to relieve pain and other joint symptoms, physical, occupational therapy, surgical interventions like replacement of the affected joint in severe cases etc.

Causes
Osteoarthritis is a degenerative disease which usually seen in elderly persons, but not all the elderly persons suffers from osteoarthritis. Damage to the joints due to different stress factors and inadequate repair lead the damages in osteoarthritis.
Stress can occur due to different causes like wrong alignment of the bones in a joint due to congenital or due to some diseases of the bones, increased body weight, especially on the weight bearing joints like knee or hip joints, damage to the peripheral nerves lying close to the joints may play important role in causing osteoarthritis.
Contrary to the common belief exercise, running without any injury does not lead to osteoarthritis in the future. Similarly, knuckle cracking does not have any role in causing osteoarthritis.
Depending upon the underlying cause osteoarthritis can be of two types; these are primary and secondary.
Primary causes include family history of osteoarthritis as the disease is more common in siblings, especially in identical twins thereby explaining the hereditary basis of the disease. Other than genetic influence osteoarthritis may occur following joint injury or with excessive body weight. Sex hormones are thought to play a specific role in osteoarthritis, as this condition is found to be more common in women in the postmenopausal age group in comparison to males of the same age group.
In secondary osteoarthritis, there are certain co-existent diseases which may lead to osteoarthritis of the joints. These are diabetes, Ehlor Danlos syndrome, Wilson’s diseases, septic arthritis etc.
The ends of the bones facing the joints are covered by cartilages. These cartilages contain collagen and proteoglycan along with adequate amount of water to maintain the flexibility of the cartilages and thus to maintain free movement of the bones within the joint without any damage to the bones.
The water content in the cartilage is again maintained by different forces, namely the compressive force  moves water out of the cartilage and the driving force which draws water inside. Collagen fibers causes compressive force thereby, drives water out and proteoglycan exerts osmotic pressure thus moves water inside.
Initially the water in the cartilage usually increases as loss of proteoglycan. Gradually the collagen content of the cartilages also decreases with fall in cartilage water content and thus making the cartilages stiff and prone to injury. The collagen fibers usually undergo degeneration also there are inflammatory changes in the adjacent joint capsules as release of substances from the cartilages in the joint capsule induce inflammation.
The body tries to compensate for the degenerative damages in the cartilages by promoting bony growths known as osteophytes may arise from the margins of the affected bones which usually lead to pain and restricted movement of the affected joints.

Risk factors
Common risk factors include an increase in age, being female, malformed bones or cartilages since birth, trauma to the joints, excessive body weight, suffering from other diseases namely diabetes, Paget’s disease, hypothyroidism, etc.

Treatment
The symptoms of osteoarthritis mainly pain and inflammation can be managed by several drugs, namely acetaminophen, NSAIDs and narcotics.
Certain therapies like physical, occupational, etc may help. Pain can also be reduced by using shoe braces, splints, etc. Certain interventions like corticosteroid injections (shots) in the affected joint spaces, injection of lubricating substances etc. may also be done. Sometimes surgery is performed to correct the position of the affected bones.
Joint replacement surgery or arthroplasty is the last resort of treatment in severely affected patients.