About Ankylosing Spondylitis. Ankylosing spondylitis is a form of progressive arthritis due to chronic inflammation of the joints in the spine. Its name comes from the Greek words  ankylos,  meaning stiffening of a joint, and  spondylo,  meaning vertebra.nkylosing Spondylitis. A form of arthritis that affects the spine, the sacroiliac joints, and sometimes the hips and shoulders. In severe cases, the joints of the spine fuse and the spine becomes rigid. PubMed Health Glossary. (Source: NIH-National Institute of Arthritis and Musculoskeletal and Skin Diseases).
The most common cause of numbness in the part of the hand that you describe (the ring finger) would be carpal tunnel syndrome, which is a condition in which the median nerve, which runs down the center of the wrist, becomes pinched or inflamed.
The: The most common cause of hand pain and numbness is carpal tunnel syndrome. This is entrapment of the median nerve as it goes through the wrist. The median nerve supplies feeling to the palmar aspect of the thumb, index finger, middle finger and in most people half of the ring finger. Pain is typically worse at night.