Arthritis refers to inflammation of the joints, and it affects people of all ages. Osteoarthritis and rheumatoid arthritis are the two common arthritis forms.
Osteoarthritis is also known as degenerative arthritis, as it is caused by cartilage wearing. Osteoarthritis pain often limits patients' movement, making muscles atrophy, and causing ligaments to become lax.
Rheumatoid arthritis is a chronic, inflammatory autoimmune disorder - it causes the immune system to damage synovial joints and extra-articular tissues (including skin, blood vessels, muscles and etc.). This disease often leads to cartilage destruction and ankylosis.