Tuesday, August 14, 2012

What Are The Parts Of A Total Knee Replacement?

One of the most common questions we hear at St. Peters Bone & Joint Surgery is something like, “Exactly what happens when you do a knee replacement and what is it made of?” 
It first might be helpful to clarify that when we say “total” knee it means we’re talking about replacing the worn out ends of the bones on both sides of the knee.  This is in contrast to a partial knee replacement where typically just the inner half of the ends of the bones that are replaced.  In addition, a total knee replacement does not remove the ligaments on the inside or outside of the knee (the collateral ligaments).  Those ligaments are maintained and continue to support and stabilize your knee after the replacement.

As arthritis worsens the cartilage and the ends of the bones wear down.  The parts of the knee replacement simply replace those worn out ends with metal components.  The components are typically made of either a cobalt-chrome alloy or titanium.  A very hard, durable plastic called polyethylene fits between the metal, allowing the ends to glide smoothly as the knee bends, much like a normal knee.
Patients also ask about how much the knee components weigh.  The answer:  between 15 – 20 ounces.

*  images courtesy of American Academy of Orthopaedic Surgeons

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