You will be having your artificial knee joint implanted in the near future. Whilst this page is not intended to replace consultations with your physician, it does offer answers to some of the questions you may have. Your new knee joint is one of the best researched medical technology products available. It is an exceptional high-tech device: state-of-the-art, intelligently designed, safe and, if well looked after, highly durable.
Over the past 50 years countless engineers have worked to continuously improve artificial knee joints. Even today, there are very few medical technology products on the market which are as advanced as artificial knee joints, also known as knee prostheses in the medical world. The design, material and production process all satisfy the highest of standards. Atraumatic surgical techniques ensure that you will be quite literally back on your feet soon after your operation.
Wear and tear in the knee joint are a natural part of aging. Physicians refer to this as osteoarthritis. The cartilage covering the end of the thigh bone (femur) and shin bone (tibia) degenerates over time. In extreme cases this can be very painful. People who do a lot of sport can also suffer from osteoarthritis in younger years.
The knee joint is the largest joint in the body. It comprises the femur with its two condyles, the tibia, the patella (kneecap), the meniscus and the collateral ligaments.
The knee joint is surrounded by several layers of muscle and a joint capsule made of connective tissue. The surgeon firstly opens up the joint so as to expose it. He then prepares the worn joint surfaces of the tibial head (Fig. 1) and the femur (thigh bone) (Fig. 2) for fixation of the joint prosthesis components. The surgeon can choose from prostheses in a variety of sizes. The joint prosthesis is implanted which represents the ideal fit for the patient.
The surgeon uses precision-made templates and cutting blocks to prepare the degenerated joint surfaces. The clear focus here is on conserving as much bone as possible. The reason: As much healthy original bone as possible should be available in the event that the prosthesis needs to be replaced at a later date. Following preparation of the joint surfaces, trial prostheses are used to check the stability and fit of the future joint replacement.
Conserving as much bone as possible - that is the most important goal when replacing a knee joint. The type of artificial knee joint you are given depends on the extent of wear and tear. If only the inner or outer part of the knee joint is affected, it can be replaced in most cases with a sled prosthesis (unicondylar knee replacement). If wear is so severe that several parts of the joint are affected, then a total knee replacement usually has to be implanted.
If several parts of the knee joint are worn, a total knee replacement is often necessary. The basic principle here involves conserving as much bone as possible. This is achieved by designing the prosthesis element for the femoral condyle like a shell. This serves to conserve the majority of the bone. The metal “plateau” used to cover the tibial surface is based on the anatomical shape and is aligned accordingly. A further advantage of surface replacement only becomes evident in the future. Should it become necessary to repeat the surface replacement (known as revision surgery), enough intact bone would be available for a new joint prosthesis.
Fixation with special bone cement has proven successful for total knee prostheses. However, there are also knee prostheses which are implanted and anchored securely in the bone without bone cement.
Your physician will decide upon the ideal knee replacement for you, depending on your symptoms, the anatomy of your knee joint and the severity of the osteoarthritis. He will opt for a prosthetic joint whose quality and durability have been confirmed in long-term clinical studies.
Surgeons perform knee joint operations with instruments designed specially for the particular knee prosthesis. This helps to protect the knee muscles and the bones involved, and you will be back on your feet quicker following the operation.
You too can play a role in making your operation a success:
You will normally be able to stand up for the first time on the day after the operation. However, you still need to be very careful, so your physician will tell you which movements you should avoid and whether you should use crutches.
Rehab at a clinic or at an out-patient center begins a few days after the operation. With training, the muscles around the knee will become stronger each day and this will help to stabilize your artificial joint. The majority of patients can walk pain-free and without crutches a few weeks after the operation.