Joint Replacement - Good to Know
Artificial Joints – a Success Story
In 1890, the surgeon Themistocles Gluck implanted the first artificial knee joint, made of ivory and nickel-plated steel, into a patient in Berlin. The first artificial hip was implanted in 1938. In the following years, materials and techniques were improved to such an extent that joint replacement surgery could be safely and successfully carried out.
The British orthopaedic surgeon Sir John Charnley developed the prototype for the hip endoprostheses still used today. The prototype consisted of a small metal head, and a socket made of Teflon, which was later substituted with polyethylene. In 1958 Charnley carried out the first implantation of a total hip replacement (THR) using ‘acrylic cement’ (polymethylmethacrylate – PMMA for short). The ‘acrylic cement’ used back then is still used today and is often referred to as bone cement. However, contrary to how it initially sounds, bone cement is not actually a cement, but rather a plastic compound, known as a polymer, which enables stable anchorage of the endoprosthesis in the bone.
In 1972, the first bone cement with added antibiotics was developed and brought to market. Using an antibiotic-loaded bone cement can prevent potential infection of the prosthesis. Today, joint replacement procedures are common and the technology it uses is constantly being optimised. Thanks to modern surgical methods, joint replacement surgery can now be performed as an outpatient procedure, which means patients no longer need to stay in hospital. The focus is always on getting the patient mobile quickly and restoring their normal range of motion.
Lifetime of Artificial Joints
The lifetime of every artificial joint is generally limited. In addition to mechanical factors, infection is the biggest enemy of the endoprosthesis. It may become loose in its anchoring, and pain and limited mobility may develop. Surgery to replace the endoprosthesis with a new joint is then usually necessary.
Thanks to advances in medicine, the use of preventive measures, modern materials and surgical techniques, it has been possible to continually reduce the risk of infection-related loosening of the endoprosthesis. This means that the artificial joint can remain in the body for longer and longer. The use of antibiotic-loaded bone cement reduces the risk of what is known as periprosthetic joint infection.
Studies show that endoprostheses anchored using bone cement have a particularly long lifespan. This means that any revision surgery (that is, replacement of the endoprosthesis) that may become necessary can be avoided, or at least deferred for a long time.
Bone Cement and More: How the Artificial Joint is Held in the Bone
In order to benefit from your artificial joint for as long as possible, it has to be firmly anchored in the bone. There are three recognised techniques available for anchoring the endoprosthesis:
The procedure used for each individual case depends on a number of factors, including the age of the patient, any pre-existing conditions, such as diabetes and the bone quality. Globally, regional differences and the training of surgeons also play a role in the choice of endoprosthesis and surgical technique used.
Studies show that cemented endoprostheses have a particularly long lifetime. This prevents the need for surgery to replace joints or at least defers it for a long time. The infection risk is also significantly reduced when using an antibiotic-loaded bone cement.
An aside: what is bone cement exactly?
Bone cement is not actually a cement, but is instead a polymer made up of two components. The technical name is polymethyl methacrylate (PMMA). It is mixed up from a liquid and powder immediately before insertion of the artificial joint, and then cures completely within a few minutes. Bone cement enables the endoprosthesis to be firmly anchored and thus enables force to be transferred between the bone and the artificial joint. Bone cement has been successfully used for more than 60 years to anchor artificial joints.
Joint replacement surgery is usually an elective procedure, so the timing of the procedure is planned in advance. This allows thorough and timely preparations to be made. The success of the surgery and the subsequent healing process depends, to a large extent, on your motivation and cooperation.
The ‘fast track’ concept has proven itself in numerous other surgical interventions and is now increasingly also being used in joint replacement surgery. The primary goal here is to get you moving as quickly as possible, to help you recover quickly from the surgery and to minimise the risk of any potential complications, such as thrombosis. Depending on the hospital, this reduces the stay in hospital significantly or eliminates the need to stay altogether. Instead of general anaesthetic, there are other options including the use of targeted local anaesthetic, which will enable you to start physiotherapy on day of the surgery itself.
It is extremely important to get moving again quickly following joint surgery. This helps to prevent complications like thrombosis and accelerates the healing process. Resting for too long not only weakens your muscles but also your immune system. You will be able to put weight on the replacement joint shortly after surgery.