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Are Minimally Invasive Knee Replacements As Good As Standard Ones?


Updated November 22, 2011

knee replacement mini minimal

A knee replacement implant

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Question: Are Minimally Invasive Knee Replacements As Good As Standard Ones?
A standard knee replacement surgery is performed through an incision over the front of the knee that measures about 6 to 10 inches long. A minimally-invasive (also called minimal-incision) knee replacement attempts to perform the same surgery though a smaller incision. In order to be called a minimally invasive surgery, the incision is usually less than 5 inches long, and the dissection stays out of the quadriceps muscle above the knee.
Answer: Modern surgical techniques are often refined to develop new ways to accomplish the goals of surgery while minimizing the side effects. A knee replacement is performed to replace the worn-out cartilage from the knee joint with a metal and plastic implant. Minimally-invasive knee replacements use the same implants as a standard knee replacement, but these implants are put in through a smaller incision.

What are the benefits of a minimal-incision knee replacement?
Advocates of minimally invasive knee replacements will claim they are accomplishing the same surgical procedure with less side effects. The hope with minimal-incision knee replacement is that patients will experience:

  • less pain,
  • faster recovery
  • less need for blood transfusion
  • less scar tissue formation

Are there downsides to minimal-incision knee replacement?
We're not 100% sure quite yet, and that is the concern many orthopedic surgeons have about minimal-incision surgery. It has to be remembered that while the aforementioned benefits of minimal-incision surgery are terrific, the most important goal of a knee replacement surgery is to provide the patient with a pain-free joint that will last a long time. The concern with performing a knee replacement though a tiny incision is that the implants may not be placed as precisely and as snug, and could therefore wear out more quickly.

A recent study found that patients requiring a second surgery (revision knee replacement) had this procedure much sooner when they had minimal-incision surgery. Patients who required the revision surgery after minimal-incision knee replacement had their revision on average 15 months after their initial procedure. This compares to an average of 80 months after traditional knee replacements. That is a very striking difference.

My doctor says the replacement is just as good--Who should I believe?
Just because I am pointing out one study that demonstrates a problem, it does not mean that minimal-incision knee replacement is a bad surgery. It simply raises a concern. There have been studies pointing out the benefits mentioned above as well. One concern with these studies showing positive results from minimal-incision surgery is that some were authored by surgeons with potential financial conflicts of interest, as well as by surgeons who are performing hundreds of these procedures, rather than just a few.

Bottom Line - Should I Have a Minimal-Incision Knee Replacement?

Recent studies are validating the concerns many surgeons had about performing a knee replacement through a "mini" incision. If you are having a minimal-incision knee replacement, be sure your surgeon has performed this procedure many times, and understand that there may be a higher chance of requiring additional surgery at an earlier time down the road.


Miller DW "Minimal incision surgery as a risk factor for early failure of total knee replacement" Paper #272. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-28, 2009. Las Vegas.

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