Ankylosis, or joint immobility, is typically caused by inflammation of the joint capsule and connective tissues. It can be due to arthritis, infection, trauma, or other systemic diseases that affect the joint. In addition, ankylosis can result from a misaligned or malformed joint, such as an abnormally shaped joint brought on by a birth defect. Ankylosis can also be caused by the progression of certain diseases, such as ankylosing spondylitis, which affects the spine and can lead to a fusion of the vertebrae. In some cases, ankylosis is caused by a combination of factors, such as a traumatic injury that leads to an infection, or a chronic disease that causes inflammation. Regardless of the cause, ankylosis can cause severe pain and disability, and can significantly affect a person's quality of life.