Dr. Eduard Rabat is an orthopedic surgeon, traumatologist and specialist in foot and ankle surgery. He carries out his activity in his consultation at the Quirón Barcelona Hospital, where he is responsible for the Foot and Ankle Surgery Unit. We talked to him about osteoarthritis and ankle prostheses.
Dr. Rabat, what is the evolution of ankle prostheses?
In the 80s, the first ankle prostheses appeared. The ankle is, without a doubt, the most difficult joint to replicate in the form of a prosthesis due to its anatomical complexity and also the sophisticated movements carried out by said joint. From the initial designs to the multitude of patients who have benefited from them. The first and greatest innovations were today, the improvements are very important, and a knee prosthesis, in which computer navigation was incorporated to increase the precision of the fit of the prosthesis to the knee and PSI (Personal Specific instrument) technology.
Recently, the most advanced technology companies in the sector have incorporated this PSI technology into ankle prostheses. In our unit we are implanting ankle prostheses with PSI technology with excellent results.
What is PSI technology?
In English, PSI means Personal Specific Instrument. It involves manufacturing part of the instruments necessary to place an ankle prosthesis in a completely personalized way for each patient. Made to your exact size in a logical evolution since no ankle is exactly the same as another.
How do you go about manufacturing these PSI parts?
This technology is an example of the growing collaboration between doctors and engineers. It requires a prior exhaustive three-dimensional study of the patient’s ankle and foot, in order to take into account the initial anatomical axis and the one we want to achieve with the implantation of the prosthesis. This requires weight-bearing x-rays and CT scans of the entire extremity up to the knee.
This information is shared with the team of engineers who, using a computer program that allows simulation, offer the surgeon a first proposal of what they consider to be the ideal placement of the prosthesis. The surgeon, based on his experience and knowledge of the case, can make the modifications he deems appropriate, discuss them with the engineers, etc. A computer platform allows the traumatologist to simulate all the changes, making it easier to decide which will be the best placement for each patient.
When consensus is reached on the perfect placement of the prosthesis, the team of engineers proceeds to make a 3D print of the patient’s ankle and, on this, generate what we know as cutting guides. These are pieces that will be fitted into the ankle during surgery and that indicate the exact point, direction, length and width where the fittings must be made so that the prosthesis is perfectly placed, following the previously calculated axes.
In your opinion, what is the main contribution of PSI technology?
First of all, it allows and forces us to carry out an exhaustive study of the case. In some ways it is like previously operating on the patient on the computer. When we receive the 3D print of the ankle we can physically touch it, place the cutting guides on it, etc. In this way we arrive at the surgery perfectly prepared, nothing is left to chance or improvisation. We have technological support that benefits the patient.
What are the indications for ankle prostheses?
Basically, ankle osteoarthritis is a consequence of both “natural” causes (progressive wear), post-traumatic (after serious accidents) or rheumatological causes. These are patients with a lot of pain, loss of mobility or, among other consequences, limping that ends up causing pain in the rest of the body.
Can a prosthesis be placed in all cases of ankle osteoarthritis?
Not in all. Very serious deformities, certain bone diseases, severe osteoporosis or complicated diabetes that affect the ankle would be some of the contraindications.
What do you think will be the future of joint prostheses in general and ankle replacements in particular?
Without a doubt, the emergence of engineering interacting with medical professionals will not stop evolving for the benefit of our patients. Surely the future lies in robotics controlled by the surgeon. We believe that, in the future, a robot driven by us will be able to implant an ankle prosthesis with unsurpassed precision. We look forward to seeing you!
