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Rediscover pain-free mobility - With your new artificial knee joint

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Dear Patient,

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.

LINK has been developing joint prostheses, made in Germany, for more than 50 years.

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.

Causes of osteoarthritis of the knee

  • Continuous overloading of the knee joint from, for example, competitive sports
  • Malalignment of the knee joint, e.g., knock knees or bow-leggedness
  • Joint inflammation and injuries
  • Rheumatic diseases
  • Metabolic disorders
  • Obesity

If your knee joint disorder can no longer be treated using conventional methods, you should consider a knee prosthesis if

  • You cannot walk and climb stairs without experiencing pain
  • You experience knee joint pain when resting
  • You have very little social life because your hip pain greatly restricts your mobility
  • You are so immobile that your physical condition is deteriorating
  • You have to take painkillers so frequently that it is only a question of time until you start suffering from side effects

You decide together with your physician when the ideal time for a knee prosthesis has arrived. Your physician will make a diagnosis, taking all the examination results into consideration, and will provide you with expert advice. 

Trust your physician: he knows when the operation makes sense from a medical perspective to alleviate your pain and thus improve your quality of life.

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 extremely strong. Over the course of a lifetime, it has to withstand enormous loads and perform countless movements. Some knee joints are more susceptible to these loads than others and therefore degenerate more quickly. 

Sled prosthesis

  • Is ideal when joint wear affects the inner or outer part of the knee joint   
  • Is fixed exclusively with “bone cement”
  • Replaces the condyle cartilage

Surface replacement

  • Causes only minimal bone loss
  • Can be implanted with “bone cement” or cementlessly
  • Leaves sufficient intact bone for the joint prosthesis to be subsequently replaced if it should be necessary
  • You and your physician decide upon the date of surgery. You also discuss which clinic you wish to go to and where rehabilitation is to take place.
  • You can donate your own blood for use in the operation around six weeks in advance if your physician recommends this.
  • On the day before the operation, you check into the clinic where you will be prepared for surgery. Together with your anesthetist, you decide whether you want a general or local anesthetic.
  • If no medical examinations are necessary, the operation is normally scheduled for the following day.
  • Rehabilitation starts on the day after the operation. Trained physiotherapists will help you with your first walking exercises using crutches.
  • After around 10 days you will be transferred to the rehab clinic or will start your out-patient rehabilitation at a center close to where you live. You will also arrange appointments for further check-ups.

One of the most important properties of a knee replacement is conservation of the bone during surgery.

Abb. 1

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.

Abb. 2

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.

The surgeon fixes the joint prosthesis in the upper and lower leg. Depending on the medical situation, fixation may either use bone cement or be cement-free.

In the final step, the surgeon reunites the upper and lower leg and checks the mobility of the new artificial knee joint. He then closes the surgical wound again. Implantation of a prosthetic knee joint usually takes one to two hours.

An artificial knee joint should replicate the natural joint as perfectly as possible. It must therefore sit securely in the bone with millimeter accuracy and perform all the movements involved in everyday life.

The material used for a prosthesis must be well tolerated by the body, promote bone ongrowth and avoid metal allergies.

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. 

Innovative materials

  • High-strength metal alloy, e.g., cobalt-chrome, offer long-term stability and have been tried and tested over decades
  • Plastics, excellent sliding and friction properties
  • Special prosthesis surfaces can help prevent metal allergies

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. 

A good knee prosthesis

  •   Must facilitate an atraumatic operation
  •   Must sit securely in the bone
  •   Must be tissue-compatible
  •   Must be hard-wearing
  •   Has been proven reliable over many years of use

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:

  • Ensure that you are in the best possible health when you arrive at the clinic. The healthier you are, the smoother the operation and subsequent healing will be.

Check list for consultations

  •   Do you feel healthy?
  •   What medication are you taking?
  •   Do you wish to donate your own blood for use in the operation?
  •   Would you like to take part in gait training? 
  • Tell your physician about any medication you are taking, including over-the-counter products.
  • Your physician should also be informed about any other illnesses, e.g., allergies.
  • Tell your physician about any infections, particularly in the mouth, nose and throat, and also any problems with your teeth, skin and nails.
  • Build up your muscles, go to gait training to improve your walking ability and, if necessary, lose weight prior to the operation. This will create the optimal conditions for your joint prosthesis.  
  • Talk to your physician in good time about the possibility of donating your own blood for use in the operation.

 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.

Important

Do not put more strain on your new knee than permitted by your physician. A newly implanted knee joint requires a certain amount of time to heal. 

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.

  • Your artificial knee joint is a very reliable and safe medical technology product. It has been developed and manufactured to allow you to be mobile again without experiencing pain.
  • Naturally, life with an artificial knee joint involves making some adjustments. Some things which were a matter of course before are no longer possible for safety reasons or require that you take particular caution. 
  • There is nothing against doing sport - in fact the opposite is true. Sport strengthens the muscles, promotes circulation of the blood and thus additionally stabilizes your knee joint.
  • Low-impact exercise involving steady and rhythmic movements is ideal. As a rule, competitive sports are not recommended with an artificial knee joint. 

Your knee prosthesis is designed to be the best possible replacement for your natural knee joint and, of course, to last as long as possible. There are numerous factors which influence the durability of your artificial knee joint. In order to ensure the longest possible lifetime of your prosthesis,

it is particularly important that you take a number of precautions, always follow your physician's advice and consult him immediately in the event of problems.
If your artificial knee joint comes to the end of its life, you can have it surgically replaced with a new one.

  •  Attend all your check-ups and consult your physician immediately in the event of any problems.
  •  Remove any trip hazards from your home, for example, loose carpet edges.
  •  Use a rucksack to go shopping as this is an easier way to carry heavy loads.
  • Avoid all high-impact sports which involve abrupt changes in direction, e.g., jogging, football, tennis and horse riding.
  • Suitable sports include cycling, gymnastics, hiking and swimming. Ideally you should choose a sport at which you are already good.