To understand the use of computers and robotics, one needs a basic knowledge of how total knee replacement are performed. For the knee to work correctly and more importantly feel right, the components have to be placed relative to the knee’s native position. To accomplish this, instruments are used to prepare the surface of both the tibia and the femur. Traditionally, the alignment of the instruments is based off the contours of the bones of the femur and the tibia. Preparation of the femur utilizes the inside of the canal of the femur, while the tibial preparation utilizes external alignment jigs based on the location of the hip, knee, and ankle.
When the lower extremity is thin and anatomic parts are not damaged, such as in trauma, these traditional preparations are relatively accurate in reproducing the proper placement of the components. However, with more difficult situations like physical deformities of the long bones, previous hardware, or obesity, the external landmarks are not easily discerned. This is where computers and robotics can be of help to the surgeon.
Computer assisted surgery (CAS) was developed originally as a way of enhancing accuracy and for 20 years CAS has been available to assist in difficult cases. However, for a number of reasons CAS never reached great popularity in the United States while being more widely accepted in Asia Europe, Australia. The reasons are multi factorial including cost, surgeon’s reluctance to adopt new technology, lack of demonstrable superiority to traditional methods, as well as patient driven enthusiasm.
CAS utilizes computer-based measurements that are read from external alignment jigs during the total knee replacement. Often this requires fine motor fiddling on the part of the surgeon. This can lead to frustration as well as prolongation of cases. This, in part, may be reasons for surgeon reluctance to adopt the technology.
In the case of robotic surgery, the tactile ability for the surgeon to align the instruments to satisfy the computer measurement is bypassed, as the robotic portion of the procedure performs this on behalf of the surgeon. This may help surgeon's reluctance to adopt this new technology by making it easier for them. As a surgeon who is used this for the past 2 decades this technology is a welcomed addition to the armamentarium of the CAS.
There are two basic forms of robotic surgery, one is passive, and the other, active. Passive means that the positions of the instruments are predetermined, followed by the surgeon manually preparing each bone. In the active form, the instruments give the surgeon feedback as they’re using it.
Both forms of the robotic surgery make it easier for a surgeon to gain a level of confidence without the interference of the surgeon’s ability to position instruments as with the CAS. They are no more or less accurate than CAS in the previous decade but do make it easier at the pre-op planning phase of the surgery.
As robotic surgery is still in its infancy, it remains to be seen whether the use of such technology will outperform both CAS and traditionally performed knee replacements in the years to come. Advocates say accuracy begets performance and those against the use of these methods would argue that a good surgeon can perform the surgery just as well without the added cost and time of the robotic assisted surgery. This is a debatable point and has yet to be solved. As for me, I have always been an advocate for accuracy. For patients who are desirous of using some form of CAS, we will continue to make this available within the constraints of insurance and governmental insurance plans.