Want to understanding the effects of mal-alignment? Think about the soles of your shoes. Walk on the outside of your feet regularly and what happens to your shoes? They start to wear on the outside.
So instead of your weight being distributed equally to the entire surface of the bottom of your foot, the forces are concentrated on a much smaller area on the outside. You wear out the lateral portion of your shoe much more quickly than the inside.
Let’s think about another common example: Wheel alignment
When your wheel alignment is off, what happens to your tires- they wear unevenly.The faulty alignment will cause some portions of the tire to be in contact with the road surface more than others and they will naturally wear faster.
Greater forces = increased wear on the surface
For a more complicated discussion of the finer points of wheel alignment go here. (I suggest this link because when you realize how complicated wheel alignment is, you will naturally wonder how complicated it might be getting your own knee aligned correctly)
Proper alignment in a knee replacement is necessary to distribute forces equally across the surface of the implant to ensure that there are no places that will wear out faster than others.
So now we come to the question of incision length.There is an optimal length where the surgeon has enough room to get the correct fit. Make the incision any smaller and you are asking him to perform the surgery looking through a hole about double the end of a paper towel roll- mostly for the sake of vanity.
Needless to say ultra small incisions can seriously impair the long term success of the surgery.
So when someone uses the marketing term “minimally invasive”, find out what they are really saying. Practically all knee replacement surgeries are minimally invasive in that no one is simply making a huge cut like they used to in the 80’s. And the majority of the surgeons use quad sparing techniques so that it takes less time to recovery. This is essentially the standard of care.
American Academy of Orthopedic Surgeons say this about minimally invasive knee replacement surgery on their website :
Minimally invasive knee replacement accomplishes everything that a traditional knee replacement does, but through a smaller incision (4- to 6-inch incision compared with an 8- to 10-inch incision). With the smaller incision come the potential benefits of a shorter hospital stay, shorter recovery, and a better looking scar.
Although there is no question that an artificial knee can be implanted through a smaller incision, doctors still don’t know whether it can be done as well as with the traditional approach.
Several early studies of minimally invasive knee replacement surgery have shown some benefits compared with traditional knee replacement, such as less blood loss, shorter hospital stay, and better motion. Other studies have shown a higher rate of complications with minimally invasive knee surgery, including poorer positioning of the knee implants.
1. Alignment matters..let your surgeon make a big enough incision to do a good job.
2. If your alignment is off, no amount of knee replacement therapy can correct that.