Hi there This condition is known as Rheumatoid arthritis. It is an autoimmune disease that causes chronic inflammation of the joints and other areas of the body. It affects small joints of hands and feet initially then progressing to ankle, knee, wrist, elbow joints.In this chronic inflammation of rheumatoid arthritis can cause permanent joint destruction and deformity. I would like to suggest you to take your mother to a orthopedic doctor and he will prescribe some laboratory tests for confirmation of the condition and will start the treatment accordingly.