Following are the terms most frequently used in discussing surgical possibilities for treating arthritis. An understanding of these terms will help you in planning your arthritis treatment with your physician.

Arthodesis: Also known as bone fusion, this is done most commonly in the ankles and wrists to relieve pain. When these joints are fused, or frozen, they are not flexible but are without pain.

Arthroplasty: Joints are rebuilt using this technique. It involves resurfacing or relining the ends of bones where the cartilage has worn away and destruction of the bone has occurred. The term also refers to replacement with prosthesis (artificial part) of the entire joint. Results of total joint replacement have been good. A better understanding of joint replacement, joint I unction, improved materials, and surgical methods has benefited many people who were disabled by pain and loss of mobility.

Arthroscopy: This technique involves visualizing the inside of joints -by looking through a thin instrument resembling a drinking straw called an arthroscope, which is inserted through a 6mm incision. Once an abnormality is seen it can frequently be repaired with special surgical instruments inserted through another small incision. Arthroscopy may be performed under local anesthesia, often on an outpatient basis, with fewer side effects and a shorter rehabilitation period than associated with arthrotomy.

Arthrotomy: The procedure during which joints are surgically opened to allow accurate diagnosis and make surgical repairs is known as arthrotomy. This procedure is being done less and less with the advent of arthroscopy.

Cartilage: The covering of the ends of the bones. The cartilage becomes frayed and pitted in osteoarthritis, interfering with smooth movement of the joint. This wear and tear on cartilage on weight-bearing joints such as the hip or knee contributes to pain, deformity and loss of mobility. In the fingers, the condition causes stiffness and a knobby look.

Joint Synovium: The place in the body where two bones join together-the tissue lining the joints. The inflammation in the synovium in rheumatoid arthritis causes the tissue to enlarge or thicken, damaging the cartilage and bone nearby. Such inflammation causes swelling and pain.

Osteotomy: This operation is performed to correct bone deformities or improper alignment of a bone. The surgeon cuts and resets the bone, permitting it to heal in a better position.

Resection: This is the removal of a bone or part of a bone. This technique is used when the metatarsal joints of the feet make walking painful and difficult. Painful bunions are also removed by resection.

Synovectomy: This type of surgery involves opening the joint and removing the membrane that is inflamed by arthritis.

Frequently, however, the synovial membrane grows back and becomes inflamed again.