Minimally Invasive Knee Replacements

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 through 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.

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.

Advocates of minimally invasive knee replacements will claim they are accomplishing the same surgical procedure with fewer side effects. Anytime a treatment can have fewer side-effects, it is seemingly an improvement.  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

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 through a smaller 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.

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.

Recent studies are validating the concerns many surgeons had about the performed 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.  Experienced surgeons will also be ready to make an incision larger if it means doing a better surgery--not compromising the outcome for the goal of keeping the incisions smaller.