Ankylosis is a medical condition that occurs when bones fuse together at a joint. The fusion can be complete or partial, and leads to severe stiffness of movement. Symptoms of the condition include joint pain and limited range of motion. Ankylosis can be caused by various diseases, including arthritis and certain forms of gangrene, and can also be caused by traumatic injury and inflammation. The condition can occur anywhere in the body where bones meet at a joint.
With so many possible triggers for ankylosis, the exact underlying cause is not always well understood. The place where the bones meet is called a joint. The bones are supposed to sit relatively loosely at that joint, allowing full range of motion in areas like the shoulders, knees, hips, and other pairs of bony joints. Ankylosis occurs when bones overgrow through a process known as ossification, the multiplication of bone cells. As the bones grow through the joint, they will fuse together, reducing the range of motion.
There are several common forms of the condition. One of the most widespread forms is ankylosis of the temporomandibular joint, where the jaw connects to the skull. It is usually caused by an infection, a tumor, or as a complication of a traumatic wound that has not healed properly. It can also be a congenital disorder.
Another form is ankylosing spondylitis, which affects the spine. It is a chronic condition that involves constant inflammation of the spine and the sacroiliac joint, a joint in the pelvis that supports the lower spine. If left untreated, this condition can cause the spine to fuse with the pelvis, resulting in a loss of mobility in the spine. This particular form of ankylosis is mostly genetic.
Treatment depends on the location of the ankylosis. In the jaw, simple exercises may be prescribed to help decrease stiffness. Similar forms of physical therapy can also be used in mild cases of ankylosis of the hip and knee.
There are also medications that can treat the disorder, especially if the main cause is inflammation. Surgery can be used to remove excess bone growth. In some cases, if the doctor believes the ankylosis will continue after the first bone mass is removed, a prosthetic bone may be implanted at the end of the joint.
It is also possible to create an artificial form of ankylosis. Doctors can induce bone growth across a joint, causing two bones to fuse together. Called arthrodesis, it is used to help heal fractures and relieve arthritis pain. This procedure is generally used only if other forms of pain medication and joint replacements have failed.