If you are looking for a medical textbook explanation, stop reading because you might be upset. My goal is an easy-to-understand conceptual explanation for a total knee replacement (TKR). This means avoiding medical jargon even doctors find confusing and maybe even making a car reference.
Let’s start with a simple fact: Knees bend. When knees bend during walking, bones must glide on one another to produce movement.
If you have ever rubbed your hands together really fast (think of Mr. Miyagi healing the injured Karate Kid) you realize friction and heat are produced, and if you keep going, you will injure your skin producing pain. Now imagine if your knees produced this amount of friction during bending when the bones glide (rub) against one another. You would not get far before your knees started hurting or perhaps caught on fire!
Why doesn’t this happen? The answer is: Articular Cartilage (AC). Ok, it’s medical jargon, but it’s necessary because it’s the crux of understanding a TKR. AC provides a virtually frictionless surface for the bones of the knee to glide during bending without producing friction, heat, or pain! In fact, there is less friction in your knees during bending than there are between two pieces of ice sliding on each other. Amazing, right?
Here is where we get into problems. If you start losing your AC, commonly due to age and “wear and tear” (called osteoarthritis), you can start having pain. Once you lose a significant amount of AC and have pain affecting the quality of your life, even after conservative treatment, your doctor may recommend a TKR.
Here we are. What the heck is a TKR? Think of how we reached this point. We lost our AC, which causes pain. Currently, we don’t have the ability to regenerate AC lost from osteoarthritis. We can only replace it with an artificial surface. During a TKR, all we are doing is removing the worn out AC and replacing it with a new artificial material (metal alloys and polyethylene) that reduce friction. We don’t change the muscles powering your knee, or the major ligaments giving stability, nor do we remove large amounts of bone. We merely replace what was lost and restore balance to your knee. Simply put, a TKR is like changing the tread on your car’s tire.
Dr. Corrales specializes in the management and surgical treatment of degenerative and arthritic conditions of the shoulder, hip and knee. Please join him on Friday, June 10th from noon to 2 p.m. at Casa Colina for a free community luncheon and seminar entitled, Joint Replacement Surgery at Casa Colina Hospital: Expect a higher standard. Please RSVP to 866/724-4132.
Luis A. Corrales, M.D., Orthopedic Surgeon & Joint Replacement Specialist, Director of Joint Replacement Surgery at Casa Colina Hospital and Centers for Healthcare