The gliding joint, also called a plane joint or arthrodial joint, is a type of joint in which the articulating surfaces of the involved bones are flat or only slightly curved. Joints are important structures in the body that connect bones and allow movement and shock absorption. The ends of the bones that connect in the joint are called articulating surfaces. The unique, flat shape of the articulating surfaces in a gliding joint let the bones slide over one another, often allowing a large range of motion. These joints are present in the spine, wrist, foot, and the clavicle.
The shape of the articular surfaces in a joint help determine how the joint will work. Ball and socket joints are shaped as their name would suggest, and they move rotationally. The shape of hinge joints allows them to move in one direction, like a hardware hinge. For the same reason a flat rock travels more easily over a flat surface than an uneven rock slides over an uneven surface, the shape of a gliding joint is ideal for gliding motions.
Even with flat surfaces, however, the bones in gliding joints cannot move smoothly without lubrication. As a synovial joint, the gliding joint uses synovial fluid and articular cartilage to lubricate and pad the movement of bones. Synovial fluid has the consistency of egg whites and is secreted from a nearby sac called the synovial membrane. Another structure called the bursa also secretes a small amount of fluid to keep the cartilage moist. Articular cartilage is a type of hyaline cartilage that surrounds the articular surfaces of the bones, protecting them from rubbing and wearing down.
When working properly, a gliding joint should be able to achieve an optimal range of motion without causing pain. A trauma, disease, or disorder, however, can cause aching or tenderness in the joint. Rheumatoid arthritis and osteoarthritis are two of the most common culprits in joint pain. Rheumatoid arthritis is an autoimmune disorder, or a disease in which the immune system attacks healthy tissue, that predominantly targets the joints in the hands and feet, where the gliding joints are. This disease is degenerative and incurable, though there are many treatment options. Osteoarthritis is the result of wear on the joint over a long period of time and also has no cure.
Chronic strain on the joint can also contribute to injuries or a disorder such as bursitis, a swelling of the bursa. A fracture of the bones due to an injury can impair the cartilage, change the orientation of the bones, or put pressure on nerves. Treatments may include operations, a brace, and resting the affected gliding joint. Likewise, defects in the shape of the bones can also cause friction and the pinching of nerves.
