John D. Burrow, DO
As a fellowship-trained Orthopaedic Adult Joint Reconstruction Specialist, I perform joint replacement surgeries of the knee and hip AND joint revision surgeries for both. Knee replacement is a very effective way of treating painful arthritis in the knees and close to 800K are performed in the United States each year. This number is expected to grow into the millions over the next decade, as Americans want to have a better, active quality of life for as long as they live. Knee replacements help many people to remain very active.
Currently, about 7-10% of knee joint replacements fail every year. Failure means that the implant is not functioning in the knee as intended and may likely be causing pain and dysfunction. There are a variety of reasons for knee implant failure that I see in my practice. In this article, I will briefly describe the major reasons for failure and how I help patients handle this issue.
Implant “Old Age”
Today’s implants are marvels of modern technology and chemistry. Space-age metal alloys and specially-formulated polymers with plastic properties are used to build knee prosthetics that are laboratory tested for wear and tear. Many boast that they will last 20-30 years in a person’s knee.
Whether you had your knee replacement twenty years ago or had it replaced today, if you live long enough, it will wear out (the metal, ceramic or “plastic” components may degrade) or loosen as the surgical cement weakens and pulls away from the bone. When that happens, you may experience pain or swelling, the knee may “catch”, click or squeak, you may limp, and your range of motion may be affected, making it hard to walk, bend or squat.
The only treatment for an old knee implant is to replace it with a new one.
Let’s face it, life happens and it doesn’t stop just because you have a knee replacement. People who have knee replacements are encouraged to be as active as possible and enjoy their pain-free movement. So, just like everyone else, they are susceptible to injury and accidents that might impact their replaced knee joint. Falling from a ladder, tripping over the dog, getting into a car accident, falling on the ski slopes or slipping on the ice are all scenarios in which a fracture might result. Fractures that occur around the implant are called peri-prosthetic fractures and they may cause instability, pain and difficulty walking or bending. The remedy? If it doesn’t heal on its own over time…you got it – a knee joint revision surgery.
About 1 in 100 knee replacements will become infected. Despite all of the efforts made by the patient, hospital, surgeon, surgical instrumentation provider, etc. to prevent surgical infections, they still occur. Infections that occur in a newly replaced knee must be treated aggressively and quickly to prevent catastrophic worsening. Six weeks of IV antibiotics are usually tried first. The knee may also be re-opened, contaminants cleaned out and flushed with antibiotics (debridement). IV antibiotics may be required for many months to combat the worst infections. The worst case scenario requires that the implant be removed, an antibiotic spacer put in its place, and for the knee to heal from all infection BEFORE being re-implanted with a prosthetic. This can require months of recovery time.
I see patients who come to me within months of having their knee replacement surgery, because they are still in pain, limping and/or do not have the expected range of motion for the length of recovery they have completed. When this happens, I usually watch the patient walk, discuss their symptoms, study their pre-surgical MRI and often order a post-surgical MRI to see what might be the issue causing the pain and dysfunction. Usually, the only remedy is a knee joint revision surgery.
Sometimes, surgeons make mistakes during implant surgery. This could happen when shaping the bone to receive the implant, cementing the implant in place or in other phases of the surgery. The implant may be loose, poorly aligned or fitted to the patient’s boney anatomy. That is why it is so important to choose your surgeon wisely, ensuring they have the fellowship-training and experience to perform your surgery well. In doing so, you are more likely to experience a better recovery and get the pain-free movement in your replaced knee that you desire, which will allow you to dance, play tennis, swim, garden, run after your grandkids or whatever you enjoy.