Ankylosis from a Greek word meaning crooked, or bent, is a stiffness of a joint because of abnormal rigidity and adhesion of the bones of the joint that can be the result of disease or injury. This rigidity can be partial or complete and might be caused by muscular as well as inflammation of tendinous structures outside joints or of the joint tissues themselves. Noma – which is a gangrenous disease that is still widespread among children who are malnourished and live on the boundaries of the Sahara desert – can develop ankylosis of the mandible and maxilla, impairing any ability to speak or eat.

Ankylosis can be the destruction of membrane – the membrane that is the lining of these joints or by bone structure that is faulty. It is more often caused by rheumatoid arthritis that is chronic, where the joint that is affected, has a tendency to undertake the position that is least painful and can become in some cases fixed permanently in that position. Other causes include traumatic injury as well as infection to the joint. Artificial ankylosis or arthrodesis, fusion of a joint by surgical procedure, is sometimes done to make bearable any pain experienced in a severe joint condition.

Ankylosing spondylitis is a type of inflammation of the spine as well as the sacroiliac joints that is chronic. The sacroiliac joints are positioned in the lower back where the sacrum – the bone positioned directly above the tailbone – meets the bones of the iliac which are the bones on each side of the upper buttocks. Inflammation that is chronic in these areas causes stiffness and pain around and in the spine. As time passes, chronic inflammation of the spine – spondylitis – may lead to a total cementing together – fusion – of the vertebrae which is a procedure referred to as ankylosisi. Ankylosis leads to mobility loss of the spine.