Redefining Knee Replacement: A Journey from Hand Saws to Artificial Intelligence

Shahid Akhter, Consulting Editor, FEHealthcare, spoke to Dr. Ashok Rajgopal, Group Chairman, Orthopaedics, Medanta, Gurugram, to trace the four-decade journey of knee replacement surgery, its technological evolution, and the future shaped by robotics, AI, and patient expectations.

 

From using wooden blocks and hand saws in 1987 to robotics and AI today, you’ve witnessed the full evolution of knee replacement surgery. Looking ahead, what do you see as the next big breakthrough that will redefine patient outcomes in the coming decade?

Well, I think it's a momentous occasion not only for me but also for the institution and my department. Let me go back in time to when I did my first total knee replacement. It was the first bilateral surgery in the country. "Bilateral" means we did both the knees at the same time. And I did this on the 24th of April 1987. Interestingly enough, the name of that patient was Sushila Jain.​ This surgery was done at Moolchand Hospital. It's been an amazing journey from there to where we are today. Coincidentally, the patient who was my 40,000th total knee replacement was also Sushila.​ It's been quite a journey, from doing total knee replacements using very, very rudimentary instruments to where we are today. We actually created some of these instruments out of blocks of teak wood. The instruments that we used to cut the bone were really sort of hand saws. There was no concept of technology at that point in time. Over the years, as we evolved, we have gotten more adept at using technology​ and more of the instrumentation.

We've come a long way from the time we did our first knee replacement. We did not have many options in terms of implant availability. We didn't have the options of different sizes or different types of plastics or polyethylene that we have today. Today, when I think about going from doing my first knee replacement surgery with just one size of both the femur, which is the thigh bone, and the tibia, which is the leg bone, to having almost about 18 sizes in my armory at any given point in time, I realize the distance we’ve travelled.​ Today, we have the latest in terms of design options, in terms of technology, availability of products, and different types of plastics, some of which are vitamin E infused, which is the latest generation. We have robotics, augmented reality, and artificial intelligence. So, yes—it's been an absolutely amazing journey and a very enjoyable one at that.

Over the last almost 40 years that I've been doing knee replacements, I've pretty much embraced every technology that has been introduced into the realm of total knee replacements. Be it the so-called minimally invasive surgery, the PSI, the patient-specific instrumentation, or the computer navigation, we've used something called iAssist, which is a gyrometer-aided surgery, through to its current iteration—which is the robotics, the buzzword today.We have adapted, embraced, and walked the distance with every single technology that has been innovated in this field, and we have experience with each of them.​ Over the years, what we've learned is that technology is additive. It is not exclusive. And the fundamentals of total knee replacement continue to be governed pretty much by the same philosophies and principles that we started off with, which are to get a well-balanced knee.​ Today's perception of a well-balanced knee is quite variable. There are various options available, and surgeons have their own preferences. The last point I wanted to mention is when I started almost 35 years ago, the apex of the common age group of patients who used to come to us was really in the 65 to 70s. In fact, we tried our best to not take on patients who were too young because we were not really sure about the lifespan of these implants. Today, interestingly, across the world and across various registries, the commonest age group of patients undergoing knee replacements is 50 to 55 years.

 

How does this shift in understanding — from a 15–20 year lifespan to potentially lifelong implants — influence your surgical decisions and patient rehabilitation strategies today?

Let me start by saying the future is pretty much in the present. The fact that earlier implants, done without technology, lasted 25 to 30 years (we now have at least over 100 patients who are 27 and a half years old or older), I think a fair comment is that with technology we can improve the quality of materials and increase the life of the implant significantly.​ As I said, technology is additive. It is definitely here to stay. Robotics is here to stay.​ Whether it is in its native form as we know it today or whether there is going to be the addition of augmented reality and artificial intelligence is another subject completely. But I personally feel that total knee replacement has reached a level of maturity. I use the word "maturity" primarily with a concept and an understanding that today's patients will do well if the surgery is done well and if patients are rehabbed well.​ Today, we would like to even start saying that a patient who has a knee replacement at the age of 45 to 50 years might well have that one replacement surgery for the rest of his life. A concept that is beginning to evolve, and that we have started to talk about in a lot of our meetings, is that if a knee lasts 20 to 22 years without any attrition, it will probably last a lifetime. So, while earlier we used to say the life of a knee is 15, 17, or 20 years, today we are talking about 25-27 years.​ I think in the next 2 to 3 years, the biggest change in understanding will be that a well-done knee replacement, which has lasted 20 to 25 years, will probably last a lifetime. 

 

​How do you see technology as a tool that can help bridge patient expectation gaps​?

Artificial intelligence is a very nascent concept at the moment. Here I would like to make an anecdotal statement: Geoffrey Hinton, who is the father of artificial intelligence, actually cautioned us on the role of AI, and I am saying this with particular reference to knee replacement surgery.

The point to consider about knee replacement surgery is managing our and the patients’ expectations. What was the patient’s activity level prior to surgery, and what are we able to give him? The patient base is a very varied spectrum. When I started off more than 35 years ago, most of the patients had been suffering with arthritis for upwards of 25-30 years. Today, fortunately, that cohort of patients has diminished to maybe 2 to 3%. It is important to understand that the level of disability of a patient when he or she comes in for surgery dictates the outcomes and results. If the level of deformity and disability is severe, he or she is not going to get the kind of results that a patient who presents relatively early in the disease process does. It is a bit like comparing apples and oranges.​ This is a point that often disappoints patients—they compare themselves with somebody else and say that the other patient is doing so much better than I am. The reason for that is the start point. If you start at the right stage, you are expected to do 90 to 95% of activities that most people need for activities of daily living, including recreational sports, gardening, swimming, golf, and so on.

Having said that, if a patient has been severely disabled or for any reason has been bedbound or wheelchair-bound for a period of 6 to 8 months or 10 months before surgery, that patient's activity levels at the end of a successful knee replacement surgery will definitely not be in the same dimension as the earlier cohort of patients. So I think it is also important today for us to be able to analyze the disability of the patient and the limitations that the patient is likely to have after surgery. This is not a uniform platform.

Two patients undergoing the same surgery may well have very different results. The one thing that we are doing increasingly, at this point, is spending considerable time counselling patients preoperatively so that we are able to titrate their expectations and are able to tell them what they can expect at the end of the surgery.​ In a patient with two knees that are afflicted with arthritis, the results on the two sides may well be quite different depending on the etiology and pathology. So I think managing patient expectations and explaining to the patient what they can or cannot do is going to go a long way. In our language, we call this the satisfied or the dissatisfied patient.​ After knee replacements, people talk about the dissatisfied patient. We have a cohort of roughly about 6-8% of patients who are unhappy with the outcomes. Unlike after hip replacement, where most patients who undergo hip surgeries are very satisfied.​ I think the difference really is because after knee replacement, the patients’ expectations are at a variance to what we are able to provide. I think it is very, very important to have an honest and frank conversation with the patient. Tell them exactly what their level of activities after the surgery is likely to be in the context of where we start off.