Artificial knee: A replacement for the human knee. An artificial knee typically has a metal shell on the end of the thigh bone (the femur), a metal and plastic trough on the shin bone (the tibia), and sometimes a plastic button in the kneecap (the patella).
An artificial knee is exchanged for the human knee by a surgical procedure known as total knee replacement. The procedure is done by separating the muscles and ligaments around the knee to expose the inside of the joint. The ends of the thigh bone (femur) and the shin bone (tibia) are removed as is often the underside of the kneecap (patella). The artificial parts are then cemented into place.
Knee replacement is done on people, usually over 55, whose knees have been so damaged by arthritis, trauma, or other destructive diseases of the joint that they have severe pain, stiffness, instability or deformity (lock-knees or bowlegs) of the knee. The most common reason for knee replacement is osteoarthritis.
An artificial knee is not a normal knee nor is it as good as a normal knee. The main long-term problem is loosening which occurs because the cement crumbles or the bone melts away (resorbs) from the cement. These problems may require repeat knee replacement surgery.
- Artificial pacemaker
Artificial pacemaker: A device that uses electrical impulses to regulate the heart rhythm or reproduce it. An internal pacemaker is one in which the electrodes to the heart, the electronic circuitry, and the power supply are all implanted internally, within the body. Although there are different types of pacemakers, all are designed to treat a […]
- Artificial pancreas
Artificial pancreas: A machine that constantly measures glucose (sugar) in the blood and, in response to an elevated level of glucose, releases an appropriate amount of insulin. In this respect, an artificial pancreas functions like a natural pancreas.
Aquaporin: A water channel. Aquaporins form pores in the membranes of cells and selectively conduct water molecules through the membrane, while preventing the passage of ions (such as sodium and potassium) and other small molecules. Aquaporins are typically composed of identical subunit proteins. Water molecules traverse the narrowest portion of the water channel in single […]
Aquaphobia: An abnormal and persistent fear of water. Sufferers from aquaphobia experience anxiety even though they realize the water in an ocean, a river, a lake, a creek or even a bathtub may pose no imminent threat. They generally avoid such activities as boating and swimming. Around the house, they may fear the water in […]
Ascariasis: Infection with Ascaris lubricoides, the intestinal roundworm, the most common worm infection in humans. Ascaris eggs are found in the soil. Infection occurs when a person accidently ingests (swallows) infective ascaris eggs. Once in the stomach, larvae (immature worms) hatch from the eggs. The larvae are carried through the lungs then to the throat […]