Hinge joints are places in the human skeleton where the ends of bones meet and rotate uniaxially (in a single plane, like a knuckle or elbow). They are lubricated with synovial fluids, secreted by the synovial membrane, to ensure easy, pain-free movement.
Description
Hinge joints, also called ginglymi or ginglymus joints, act like the hinges on a cabinet or door to provide back and forth movement. However, unlike their hardware namesakes, hinge joints provide more movement than just back and forth swing. They have a varying spiral profile that allows some rotation. The interphalangeal (finger) and humeroulnar (elbow) joints are examples of the hinge joint. The knee is also a hinge joint.
Function
The purpose of joints is to provide movement for the body. Different types of joints move in different ways. The hinge joint is shaped to restrict movement to one plane. It has strong collateral ligaments that aid and restrict movement. The ends of the bones are covered with tough cartilage and are lined with the synovial membrane.
Each joint contains a small amount of synovial fluid which lubricates it. Synovial fluid provides protection for the hinge joint and allows for its stress-free movement.
The hinge joint provides a connection that allows articular surfaces to be closely molded together. This molding together permits extensive motion in one plane. The joint has stabilizing ligaments that limit the directions and extent to which the bones can be moved. The hinge joint moves back and forth with some rotation allowed.
Role in human health
Because synovial joints are the most mobile and intricate of all the joints, they are also the most prone to disease. Healthy hinge joints allow effortless, painfree mobility; diseased hinge joints are not only a source of physical pain, but also place severe limitations on movement. These limitations, in turn, can have adverse psychological consequences.
Common diseases and disorders
There are many disorders and diseases that can afflict the joints, making the hinge joints vulnerable to pain and discomfort. Degenerative and inflammatory diseases, conditions involving the membranes around the joints, generalized and congenital disorders, and dislocation and fractures can all cause damage to the hinge joints.
Arthritis is one of the conditions that causes pain and dysfunction in the hinge joint. There are several types of arthritis, but osteoarthritis and rheumatoid arthritis are the most common.
Osteoarthritis is a degenerative disease that affects the cartilage in the joints, and can cause inflammation in the tissues surrounding the affected joint or joints. Degeneration is commonly thought to be caused by stress on the joints or by injury to the joint lining. Osteoarthritis can affect all joints, but it is usually found in the fingers, feet, hips, spine, and knees. It causes joint stiffness and pain. Symptoms of osteoarthritis can be treated, but the disease is irreversible.
Rheumatoid arthritis is an inflammatory disease of the muscles and the membrane linings of cartilage and joints. The areas commonly affected are the hands, hips, knees, legs, and joints. The symptoms include low-grade fever, stiffness in the morning, and redness, pain, warmth, and tenderness in the affected joints. Rheumatoid arthritis can cause crippling pain and deformities of the hands and causes painful swelling of the joints.
Bursitis is a common disorder that affects the hinge joints and other joints. It is most often found in the elbow, knee, and shoulders. Bursitis is the inflammation of the bursa, flat sacs that surround the joints. Symptoms of bursitis are swelling, tenderness, pain, and warmth around the joint. The inflammation of the bursa is usually caused by overuse or injury of the joint. Two common types of bursitis are "housemaid's knee," which is caused by kneeling on hard surfaces for an extended period of time and "student's elbow," which is caused by leaning the arm against a desk or other hard surface.
BOOKS
Irons-George, Tracy. Magill's Medical Guide. Vols. 1, 2, 3. Pasadena, CA: Salem Press, 1998.
Williams, Peter L. Gray's Anatomy. 38th ed. New York: Churchill Livingstone, 1995.
PERIODICALS
Manek, Nisha J. "Osteoarthritis: Current Concepts in Diagnosis and Management." American Family Physician (March 15, 2000).
Sadovsky, Richard. "Preventing Progression of Rheumatoid Arthritis." American Family Physician (March 15, 2000).
National Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse (NAMSIC), National Institutes of Health, 1 AMS Circle, Bethesda, MD 208923675. (301) 495 4484 or (877) 22-NIAMS. TTY: (301) 565 2966. Fax: (301) 718 6366. <http://www.nih.gov/niams/>.
Axis—A central or principal structure about which something turns or is arranged. The hinge joint has one axis.
Bursitis—Inflammation of the bursa—flat sacs that surround the joints—usually caused by overuse or injury of the joint. "Housemaid's knee" and "student's elbow" are common forms of bursitis.
Osteoarthritis—A degenerative disease, usually found in the fingers, feet, hips, spine, and knees, that affects cartilage in the joints, and can cause inflammation in the surrounding tissues.
Rheumatoid arthritis—An inflammatory disease, related to a streptococcus infection, that affects muscles and the membrane linings of cartilage and joints. It can cause crippling pain, deformities of the hands, and painful swelling of the joints.
Synovial fluid—A transparent, viscous fluid found in the synovial joints. It lubricates the joint for easier movement.
Uniaxial—Having only one axis. The hinge joint is a uniaxial joint.
