Both minimally invasive knee replacements and traditional knee replacements are performed to alleviate chronic knee pain due to arthritis, and both surgeries require the cutting of soft tissue and bone in order to implant prosthetic knee joint components. The difference is that a minimally invasive knee replacement uses a smaller skin incision and tends to require less cutting of other soft tissue, such as muscles, tendons and ligaments.
The expectation is that less invasive knee replacement techniques will allow for an easier post-surgical recovery in the short term and provide equal or better results in the long term. Whether this expectation is realistic is a matter of ongoing research. To date, experts have found minimally invasive knee replacement surgery has both advantages and disadvantages, and it is not appropriate for all knee replacement patients.
What Is Minimally Invasive Knee Replacement?
Several surgical approaches to knee replacement are considered "minimally invasive." What characterizes a less invasive surgery is that the surgeon makes a smaller incision and works within a smaller surgical area than a traditional knee replacement surgery.
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Below are four examples of how traditional and minimally invasive knee replacements are different from one another:
- A traditional knee replacement surgery requires an 8 to 12 inch incision down the middle of the knee. Minimally invasive knee replacement surgery requires a skin incision of only 3 to 6 inches.
- To access the knee joint during traditional knee replacement surgery, the surgeon cuts through quadriceps muscles at the front of the thigh, the quad tendon that attaches the four quadriceps muscles to the kneecap, and other soft tissue. During less invasive surgery, the incision must extend through some deeper soft tissue, but certain muscles and tendons are lifted or pushed out of the way rather than cut.
- During traditional knee replacement surgery, the kneecap is turned over 180 degrees, giving the surgeon full access to the point where the femur and tibia meet. During minimally invasive surgery, the kneecap is often simply pushed aside.
- A surgeon performing traditional surgery will dislocate the tibia (shinbone) from the femur (thighbone) before fitting both bones with prosthetics. During minimally invasive surgery the tibia may not be dislocated from the femur.
Less invasive knee replacements can differ in the exact location of the incision, the shape of the incision (e.g., curved), and how the muscles and other soft tissue are cleared out of the way to make room for the surgical procedure. The type of minimally invasive approach used typically depends on the surgeon's experience and preference. The patient's anatomy may also be a factor.
Minimally Invasive Knee Replacement Requires Advanced Surgical Training
The primary challenge of minimally invasive knee replacement surgery is that the surgeon has limited access to the knee joint, and that can affect the surgeon's ability to create an ideal prosthetic fit and joint alignment.1,2
For example, because the patella (kneecap) is pushed aside rather than flipped over, the surgeon has a limited view and restricted entryway to the tibia and femur. Advanced surgical training and specially designed surgical tools are required for surgery.