There are various types of arthritis may affect the knee joint:
Osteoarthritis:
It is the most common reason for knee replacement. It affects generally middle-aged and older adults may cause the breakdown of joint cartilage and adjacent bone in the knees.
Rheumatoid arthritis:
Rheumatoid arthritis is an inflammatory disorder that affects not only the joints but also the body's system, skin, eyes, lungs, heart and blood arteries. This disease can be treated for a long time or for a lifetime. It is an autoimmune disease in which the body's immunity starts damaging healthy cells.
A person suffering from this disease complains of joint pain, swelling and irritation. In rheumatoid arthritis, bone erosion occurs as well as the shape of the joints begins to change, causing the feet and hands or fingers to become crooked.