‘High Flex Rotating Platform Knee Replacement Surgery Lasts For 20 Years’

Dr Sanjiv KS Marya is an internationally renowned orthopaedic surgeon currently working as the Director of Orthopaedics with Max Healthcare Institute Limited, New Delhi. Dr Marya has more than 3000 joint replacements of knees, hips, shoulders, toes and finger joints under his belt, which includes primary and revision joint replacement work. He has pioneered bilateral joint replacement of knee and hip joints. Dr Marya has initiated the uni-compartmental (half knee) replacement and has done exclusive work on fractures in joint replacement. He has also introduced resurfacing hip replacement in this part of India. He spoke to Sapna Dogra about the newly introduced high flex rotating platform knee replacement surgery.

What is high flex rotating platform knee replacement surgery?

High flex rotating platform knee replacement surgery is the latest and most modern advancement in the field of knee replacement surgery. The various types of knee replacement implants available in the market do not allow one to squat or sit cross legged. With high flex rotating platform knee replacement surgery, one can do this more than partially. RPF is the only implant at the moment that gives the combination of high knee flexion and rotation. Another interesting part is the rotating movement, the advantage of rotating is that it gives movements of two planes.

What do you mean by “more than partially”?

It means that a patient can occasionally squat or can sit cross-legged. Hitherto, the implants did not have this feature. So, this implant would let a patient squat. However, the disadvantage of squatting is that when one sits down, the knee bends with so much force that by doing it repeatedly, the patient would either loosen it or in between the high density plastic would get worn off. Hence, there’s lot of strain in squatting. But with this new implant one can squat, sit cross-legged in cases of emergency. We have not yet developed the confidence to tell the patients that go home and do it as much as you want.

When did you do the first case and what is the cost of the surgery?

We got the first RPF implant in July 2005 and since then 54 patients have undergone this. The cost is about Rs 1.7 to Rs 2 lakh, which is around Rs 10,000 more than the conventional one.

Why can’t we have an implant, which would allow the normal knee function?

Well, we are working towards that. The knee is not as simple as a door hinge; it just does n’t bend and straighten, but also has a very subtle rotating movement. And this movement is in six planes not just one plane. Therefore, to produce that function is technically challenging. Research is on for the ideal implant. The RPF is the latest result and most modern of this effort that is available today. Another problem is that whenever we come up with something new, it takes a long time before it can be found how it would work inside the body. You need people who understand it and you also need money, which why we are usually a bit behind, but institutes like ours luckily have patients who can afford it.

What is the life of an RPF implant? And what is it made of?

The life of a normal knee replacement is usually about 15 years, but in RPF we are looking at 20 years. Usually, it is titanium in the fix module, but the newer model is made of cobalt chrome. There are various types of alloys with bit of magnesium and bit of chromium, but essentially it is cobalt chrome.

Tell us about your computer-aided system for RPF.

Max is the first hospital in the north India to have a computer-aided system, which is being used to do a knee replacement surgery. This machine helps in doing an incision with 0.5 per cent correct precision. The computer identifies shape and size of the joint along with various angles by degrees. Manually, one can go wrong by two to five degrees. We got this machine worth Rs 1.2 crore on May 26, 2005. To make it viable, there should be certain number of joints and hence we charge our patients Rs 75,000 per knee extra for this. We are trying to recover the cost and we can because we have the numbers.

What are the advancements that you foresee in joint replacement surgery in the future?

Minimal incision will further minimise the size of incision. Other advancements would be in hip segment on surface replacement, which would help patients sit cross-legged and squat.

Also, in hip there would be more computer-assisted surgeries along with minimal invasive surgeries. Other things that are improving are in metallurgy; the metals and plastic being used are getting better and better. Few years ago, a joint would have lasted five to seven years, but today we are safely talking about 15 years and the most new ones can last up to 20 years.

Also, I am hoping to see actual cartilage or stem cell regeneration of cartilage where one could regenerate this layer of cartilage somehow and instead of implants, one can put this layer of regenerated cartilage.

sapnadogra@expressindia.com