Total knee arthroplasties have been on the rise over the past ten years. Thus, the joint implant would be prescribed to increasingly young patients. What are the indications for a knee prosthesis? What rehabilitation?
What is a knee prosthesis?
A knee prosthesis is a internal joint implant to replace the failing parts of the knee and thus to find a better support, a better bending and to improve walking. There are three main families of prostheses:
► The unicompartmental prosthesis which compensates for only one compartment of the knee, usually the internal compartment;
► The total prosthesis which compensates for the three compartments of the knee;
► The reconstructive prosthesis used during reconstructive surgery after cancer, a road accident, the failure of a previous prosthesis already placed or a prosthesis at the end of its life. “90% of the prostheses placed are total prostheses“, specifies Dr. Arnaud Clavé, orthopedic surgeon at the Saint George clinic in Nice.
What are the indications for a knee prosthesis?
“In the vast majority of casesassures the orthopedic surgeon, the main indication is osteoarthritis of the knee. This osteoarthritis can be primary, that is to say it is due to old age, secondary then generated by a rheumatological, post-traumatic or oncological disease : some drugs can cause bone necrosis.”
At what age do you put on a knee prosthesis?
In France, according to the article Total Knee Prostheses in France: growth driven by men between 2009 and 2019the age group most affected in 2019 was the 65 and 74 years old. Ten years earlier, it was over 74 years old. “This rejuvenation is correlated by two factors: first, people don’t want to suffer as long as they used to because they have a higher functional demand. Secondly, in ten years, many surgical and material advances have taken place leading to better functional results..”
When to walk after fitting a knee prosthesis?
“From the day of the operationthe patient is supposed to be able to get up and walk but there is a interpersonal variability“The first month can also be difficult because the patient can be very apprehensive.”But generally, patients manage to plan after one month, progress after three months and moved on after six months.”
What rehabilitation after knee surgery?
Rehabilitation lasts about three months and mainly consists of getting up, walking and climbing stairs. “The physiotherapist is there to make sure to recover a walking pattern that is as correct as possible. This prevents the patient from hurting his back, or decompensating with the other hip, for example.“, explains Dr. Clavé.
What movements are prohibited with a knee prosthesis?
No movement is discouraged or prohibited when wearing a knee prosthesis. However, “do not do activities that create pain or a lot of anxiety because there is more risk of having an accident.” Running, pivo-contact sports such as combat sports, football or rugby are not recommended.
20% of patients are not fully satisfied with their prosthesis
What is the lifespan of a knee prosthesis?
A knee prosthesis can have a lifespan of 15 to 20 years. The lifespan of the prosthesis depends on several factors:
► Wear : the prosthesis is composed of a metal part in the tibia and a metal part in the femur. Between the two, a friction couple, often made of plastic, is installed. “Today plastic wears out much less quickly than before and are tested to have a life cycle of around 25 years“, assures the orthopedic surgeon.
► The unsealing : this can be caused by the loss of fixation between the bone and the implant.
► The infection : “You should know that infections rarely occur during surgery. Prostheses can become infected from a distance due to a badly treated dental abscess, for example: the body knows how to defend itself against bacteria but not the prosthesis.…”
What are the disadvantages of a knee prosthesis?
“Around 20% of patients are not fully satisfied with their prosthesis. However, the prostheses are of better quality than before, but there are more dissatisfied patients. This is due to the fact that we do not fully meet their expectations. Today people want to find the knee of their 20 years. But the prostheses are not yet able to reproduce the exact biomechanics of the knee.“Because of this, some people feel they have an unnatural knee. Others also complain of instability : “When installing a prosthesis, you have to sacrifice the cruciate ligaments which are the orchestra conductor of the mechanics of the knee. The prosthesis only partially and imperfectly compensates for this loss..” Pain in the patella and quadriceps can then be felt and full mobility may not be recovered.
Thanks to Dr Arnaud Clavé, orthopedic surgeon at the Saint George clinic in Nice.