Ankylosis is a condition in which a joint becomes immobile due to abnormal fusion of the bones that make up the joint. It can result from a variety of conditions and injuries, though the most frequent cause is trauma, such as a fracture, dislocation, or a direct blow to the joint. Other causes of ankylosis can include infection, autoimmune disorders, and calcium deposits around the joint. In some cases, ankylosis can be caused by a structural abnormality of the joint, such as an abnormally shaped joint surface or a joint that is too shallow and unable to move freely.
Infection is another common cause of ankylosis. Bacterial, fungal, and viral infections can all cause ankylosis, as can underlying conditions that weaken the joint and make it more prone to infection. For example, people with rheumatoid arthritis are more likely to develop ankylosis due to the inflammation associated with the condition. Autoimmune disorders, such as lupus, can also lead to ankylosis.
Calcium deposits can also cause ankylosis, as can the development of osteophytes, or bony growths, around the joint. This type of ankylosis is most common in older people, as the body’s ability to repair itself decreases with age.
In some cases, ankylosis can occur without any obvious cause. This is known as idiopathic ankylosis, and it is most common in children. It is believed to be caused by an underlying genetic predisposition or an unknown environmental factor.
No matter the cause, ankylosis can lead to pain, stiffness, and decreased range of motion. Treatment depends on the underlying cause, but may involve medications, physical therapy, or surgery.