Osteoarthritis is a very common joint condition. The cartilage covering the ends of the bones in the joint becomes thinner and rougher until, in places, bone rubs on bone. In the hip and knee, it often begins with start-up pain: the first steps in the morning are difficult; later, the joint also hurts at rest and at night.
Treatment starts with movement and physiotherapy, painkillers, injections into the joint and, if necessary, weight loss. In younger people, an operation that straightens the leg axis can relieve the knee. Many people manage well with this for a long time.
An artificial joint becomes an option when these possibilities have been exhausted and everyday life is clearly affected – when walking, climbing stairs, getting dressed or sleeping. Osteoarthritis is not an emergency: patients have a say in the timing. For total knee replacement, Germany also has a minimum case volume: a hospital site may only offer it if it performs enough of these operations each year.
An endoprosthesis replaces the damaged gliding surfaces. In the hip, these are the socket and the head; in the knee, the surfaces of the thigh bone and shin bone, sometimes also the back of the kneecap. The components are made of metal, ceramic and a particularly hard-wearing plastic, and are fixed with bone cement or anchored in the bone without cement.
