3D Knee

SAN ANTONIO – In the past ten years, the number of total knee replacements in the U.S. has doubled and many of those patients are much younger than ever before. 

Replacement knees typically come off the shelf in several sizes, but they don't always fit right, causing pain and other complications. Now, new technology allows doctors to make replacement knees that are the perfect fit.

A few months ago, retired pipe fitter Don Plum could hardly stand up because his knees ached.

"It was bone on bone and a lot of severe pain." Plum told Ivanhoe.

After getting his new ‘3D knees,' he now walks and even runs pain-free.

Plum had knee replacement surgery done on both knees at the same time. After a cat scan made a 3D image of his knees, a 3D printer made two new knees that were a precise fit.

Richard Buch, MD, Orthopedic surgeon at the Dallas Limb Restoration Center says the 3D knees offer a lot of advantages over typical replacement knees, which come in several sizes but seldom fit a patient exactly, and can be a source of recurring pain after surgery.

"It matches their anatomy and the bone you are taking off is less than it was with a standard knee." Dr. Buch told Ivanhoe.

Other advantages to the 3D knee include a shorter hospital stay, quicker recovery time, less pain and more movement.

Just ask Don Plum who says thanks to his 3D knees, he can do anything he wants.

3D knee replacement is covered by most insurance companies and projections are that by 2030, 3 to 4 million knee replacement surgeries will be done every year in the United States.

Richard G. Buch, MD, Orthopedic Surgeon at The Dallas Limb Restoration Center discusses new technology that is allowing doctors to make perfect fit knee replacements.

This interview is about the 3D knee, why is this better than the way it's been done forever?

Dr. Buch: Nearly all standard knee replacements are made the same across the board. The American Academy of Orthopedic Surgery states there are at least 39 different primary knees available on the market. All are premade in a factory with only six to eight sizes available. These sizes then have to be taken and fitted to your knee.  These implants are premade requiring us to cut the bone to try to match the implant. The problem is in a high percentage of patients 25-30% percent of patients do not match perfectly because every knee is unique. Some people are longer this way or shorter that way and they only make it one size this way and that way. Sometimes you match it this way but it's off and sometimes you have to put it on and it doesn't match at all and it overhangs because you have to get it big. The difference with the 3-D knee and the technology of making a knee for the patient is that now you can fit it perfectly, it results in removing less bone than with a standard knee. When you custom make one for a patient that matches their knee all you have to do is shave the bone. The implant matches perfectly to the bone, we take less bone which results in less surgery.

It would seem that taking less bone would be better for the patient.

Dr. Buch: In the old days if you came in under the age of 60 and your knees are in bad shape and you couldn't walk, we wouldn't fix your knee, we'd wait until you turned 60. That was the unwritten law and it's still out there in the community today. But now we're doing knees in people in their 50's and sometimes their 40's because their knees are so bad from trauma, different disease processes and all sorts of things. These people had no option but to live in pain. With new techniques and implant technology advancements we are replacing knees sooner. What happens is after an extended period of time; the knee comes loose and needs to be redone. The less bone removed the first time, the more bone you have to use a second time. One of our biggest disasters we faced was having very little bone to fix the knee when it came loose and when it comes loose, implants never lasts as long as it does the first time. If we only shave the bone off we conserve more bone the next time, a patient could have a standard knee placed in just like a primary and it should last much longer.

Is this technology revolutionary? Is it a miracle? What is it?

Dr. Buch: It is the next stage of the miracle process. The miracle is that the patients do better, quicker. They are able to get up and around. Is it for everybody? Does it fix everything? No, human beings just aren't that way. But the percentage of complications is less, the patients seem to go quicker and the rehab period is cut shorter. They say the knee feels more like their knee. The common thing I get from these people after years of using standard knee replacements with these new technologies is that the patients say it feels like their knee. They tell you that they have less problems than the old knee which would hurt a little bit where it rubbed on the metal where it over hanged. You have less of that soreness with these patients.

Do patients feel this technology is a lot better?

Dr. Buch: Yes, patients say this is better. I tell patients their recovery is going to be quicker, you are going to be on your feet faster, it will feel more like your knee in a few months.  I could not tell patients this previously. Patients will tell you that a standard knee always took two-three months and sometimes longer to get over it. With this technology patients are walking around with no aides at six to eight weeks.

We are talking about 3-D printers. Does this surprise you as something that would ever be used for knee replacements? Did it ever seem possible that a printer would be so valuable in making parts for the human body?

Dr. Buch: This is the next stage of technology for replacements. We are able to take a patient's knee, measure it in a CT scan, in real time create a 3-D model, then create an implant that perfectly fits to their original knee. Common sense tells you have had your knee this way your entire life, it is used to walking a certain way and functioning a certain way. Why should I take somebody else's knee and try to fit it to yours, this changes your anatomy. Using this technology we can recreate your knee using your natural anatomy, it only makes sense.

When you think about this technology compared to what you knew when you first started doing joint replacement, does it amaze you?

Dr. Buch; Well it amazes me because when I first started there was nothing, you just took a saw and matched things. The next development was a cutting box that allowed us to cut things better. Orthopedic companies then developed a minimal box so we could have less cutting. Now we make smaller incisions and put blocks on that are made for the patient to fit their anatomy. This allows me to make smaller cuts now and put a knee in that matches their anatomy perfectly. This was not possible 10 or 15 years ago.

Because of our aging population living longer, the numbers for knee replacements are going up right?

Dr. Buch: When I first started maybe 200,000-250,000 knees were done a year in the United States. Now it is over 700,000 a year and climbing. The reason is you are growing at both ends of the spectrum. The population is getting older and as we age arthritis develops. Everybody's knees and joints wear out because your joints are machined parts, all machined parts wear out. These types of patients are coming to us more and more as we live longer. At the same time we have technology that can put these in younger patients that used to be on crutches and wheelchairs or just limped around and put up with the pain for as many years as possible before having a replacement. With this new technology we can put it in sooner, allowing them to get their life back and do things they could not do before. We always tell patients that if you have a replacement at a younger that it's not going to last your lifetime, it typically lasts 10-15 years or longer. With this new technology your knee may be 20 years or longer.

You don't know yet because it hasn't really been tested out?

Dr. Buch: Exactly, this is new technology. We changed the previous technology to a new stage or standard. We think the knee will last longer but we have not put them in for people 15 -20 years yet. These knees will last at least 10 or 15 years, I think it's going to last 20 years or longer.

Show us how it kind of works if you can.

Dr. Buch: We order a CT of the patient's knee; from here the images are uploaded to a computer allowing the printer to create a 3-D model. Next specific cutting jigs are created to allow a perfect cut during surgery. The old standard technique had big blocks requiring the surgeon to put holes in the knee with bars sticking out while these big blocks would sit there while the bone was cut. This obviously takes more bone away. These new jigs are made to fit perfectly on the patient's knee and are extremely lightweight. These jigs match the anatomy with a perfect fit. Then you drill your holes and there's a cutting block that fits here and when you take it off and cut it, all you're doing is taking less bone and that little bone is half the size of what a normal bone is. You do the same thing on a tibia side and this is what a femur looks like after we cut it, then you put a femur in like this and the metal just sits perfectly with less bone taken off. On the flat side, which is your tibia side, the same thing happens. We have jigs that sit perfectly on the bone and fit perfectly in the notch and does not move. We have a little box here that the saw goes through shaving off the top of bone, much less than we used to. Traditionally we take around 12 millimeters off and now we're taking six millimeters off. By taking that bone away you just have a component like this which is the tibia that sits in there and goes together with plastic. The plastic fits in there so it does not hit together. Here's your knee with it fully together, the plastic is in between those notches allowing your knee to rotate, this is how your knee works. These parts and pieces are made specifically for the patient, even the plastic is made for the patient to fit perfectly, it comes in different sizes so you can balance them out after you make your cut.

Would you talk about these jigs and things like that? It's kind of like making a key right? That's what the jig does it creates a guide for your saw?

Dr. Buch: Right, it's a key to your knee and it's made specifically for you. It does not fit anybody else; it only fits your anatomy. Instead of guessing where the cuts were supposed to be made we have slots that tells you exactly where to cut. This is already premeasured telling you how much bone you are supposed to be taking off.  This allows you to know how much you are taking off each time and is aligned all the way around. You have perfect machine cuts just like you can get in a machine shop. We could not achieve this type of precision before.

I imagine there's a procedure, you probably have to do the steps in order, is that right?

Dr. Buch: You always have to do the steps in order. There is a system in place of how you do things. What happens here is that you take out a lot of hassle with this technology. It comes in a big box and all you need to do in the end is saw. In the old technique you had large pans that weigh at least 40 pounds, at least five or six of them that your staff has to carry around and pile up in the back that have all the different instruments to do a knee. All that would take up space and had to be processed because it had to be sterilized. Now this knee comes in a little box with all the little parts and pieces that match a patient, this is all we use. This drastically reduces the need for additional operating room staff.

One might think that this new technology, cost-wise, would be through the roof because of these efficiencies. Apparently it doesn't cost much more than traditional knees.

Dr. Buch: No, what happens is you're saving money on the backside and you're costing just a little bit in the beginning. It takes a little bit more to get these things measured, not a tremendous amount. You're not talking about thousands of dollars. You're just adding a little cost. But the little cost comes at a big savings because the patients are in the hospital less time so in this day and age patients have to pay for being in the hospital and the longer they are in the hospital the more costs they occur. Additionally hospitals save money. The longer the patient is in the hospital, the more money that gets lost in the system. This allows the patients to get out quicker, faster, they can go home in one or two days, sometimes the go home the same day. We have program set up that if the patient does the right thing, they get educated beforehand they can go home the same or the next day after a joint replacement.  Most of our knee patients with this kind of technology stay in the hospital twenty-three hours.

Plus you don't have all that inventory, all that stuff that you have to constantly be sterilized an carrying around and storing right?

Dr. Buch: Correct. In the detail room of the hospital every rep has their instruments there. All hospitals have a large designated area with nothing but piles of instruments, prostheses and various equipment from different companies. Each one of these knees are made for a patient, it comes in a box with no storage. They are delivered to the patient just like a UPS person would deliver a small package. It is specifically made for that patient's knee, when you finish with it you throw away the used components.  There is no storage and a hospital does not have piles of prostheses and instrument trays.

So really for just the analogies that people understand it's the difference between buying your suit off the rack or have a custom-made suit perfectly for you?

Dr. Buch:  Exactly, the measurements and sizing are determined to fit perfectly before receiving a custom made suit. This will guarantee a perfect fit to the specific individual. If someone buys an off the shelf suit the pants or sleeves maybe to long or short, it is the exact same concept with this knee technology. Off the shelf implants come in predetermined shapes and sizes, the bone must be shaped to fit the implant.  When buying an off the shelf suit a tailor must modify the suit, making cuts to achieve a better fit.

Are you finding that you're getting fewer complaints and less comebacks because patients are doing better with this knee technology?

Dr. Buch: From start to finish I get fewer complaints from the scrub techs that are in surgery because they don't have numerous instruments, everything is right in front of them. I get fewer complaints from the hospital because patients go home faster. I get fewer complaints from the patients because they are going home earlier. They are up and walking around faster their walking with no aides, they feel like it is their natural knee. All around it is a win for the patients, the hospital, and for me as I know I am giving the patient a natural feeling knee.

And what you get out of the deal, less aggravation?

Dr. Buch: What I get out of the deal is a patient who says thank you. I became an orthopedic surgeon to get patients up and moving around, to give them their life back, all they need to say is thank you when they come in for follow up appointments. In fact when they come in the office the first time they are not moving around, they just sit at home not doing much, they will not go shopping, or their can mow the lawn anymore.  Following surgery they can do things again that most take for granted like working in the garden or standing up to cook a meal again, this is the ultimate satisfaction. I am providing patients with a perfect fit knee to reduce or eliminate pain allow them to regain their healthy active lifestyle.

So really when you talk about this especially since we have this old aging population this is the kind of thing that's going to make it for a better quality of life as all of us goes through the stuff.

Dr. Buch: Everything that we do and this kind of technology is always about a better quality of life, but sometimes a better quality of life comes at a high cost. This one doesn't come at a high cost. It gives you a better quality of life quicker and allows you to get your life back. The funny thing is with male patients they are very reluctant to come to the doctor. But when they finally come in and have their knees done every single one says, I wish I would have done this years ago. Because you're always scared about the process but now the process is easy, this is an easier process. Less complications, one of the biggest problems was complications with surgery was wound problems because you made bigger incisions, a lot of bleeding so they bleed excessively and get what is called hematomas. They get more wound problems and blood clots because you have to open up the knee, make bigger incisions and this messes around with the blood flow and the vessels to the area causing a whole bunch of problems. Now you are making a small incision, you are making precise cuts, you are not violating anything, you do not get a lot of bleeding, you have less blood clots, less swelling, and patients go home faster. It is a complete win doing it this way.

There's a company that makes this and there are other companies that make the other types, is this going to change the game is this particular technology is going to change the game?

Dr. Buch: That's a good question because were always looking for the next thing to change the game. You always kind of predict what it's going to be and because in here and my Institute we always look for the next best thing for patients. We have researched numerous technologies and no one really had the thing that took it to the next step. This one has been completely different because I can do a total knee and send the patient home the same day. You cannot do that with anything else. The patient comes back and tells me it feels like their own knee I never get told that previously, patients are coming back walking without any aides and they are already out doing things. Some of the patients even come back and tell me their jogging, they are standing around, they are jumping and they are doing things because it just feels more like their knee. Right now this is what the new technology looks like; it is the new best thing until the next new thing comes up. This has been a major step from where knee technology was to now. Typically technology makes small leaps and this has taken knee technology to the next level.

Guys like you or people in the business are they skeptical or reluctant to move in this direction? Is this the kind of technology that other physicians should be looking at?

Dr. Buch: This is the type of technology that other people are all trying to dabble in. You have something called patient specific knees, they are not really knees made for the patient they are just cutting blocks. A lot of companies make those now, some are better then others but they are not custom knee implants. The problem is that they do not fit quite as well. It still takes off more bone, because they are cutting the bone to match their knee. They are not changing the technology they are still taking their knee and trying to make it fit your knee, these blocks make it easier for the surgeons. This is not what this technology, we are cutting your knee taking less bone and then putting back in your knee back in the way it originally was. This is why patients come back and say, this feels like my knee because it is. I am putting your knee back in with this technology. I am not taking somebody else's knee and putting it in because that would never feel like your own.

And that's where the 3-D printer comes in.

Dr. Buch: Exactly.

Because they are not using the 3-D printers?

Dr. Buch: They are not using this technology where they make a knee for an individual patient. All they do is make blocks that cut bone. What they put in is just always what they have they're just trying to make – help the doctor make the cuts a little better thinking that was going to solve the problem. It does not, there's a lot of technology that goes into this and a lot of other things about balancing that you can't address with that.

So essentially it's well which is better changing the components to fit your knee or changing your knee to fit the components.

Dr. Buch: Exactly, that's exactly what it comes down to. And it makes sense if you take less bone away you're messing with less of the tissue, you're not affecting your ligaments as much and then you're putting a knee in that matches yours common sense would tell you that should work better. Whereas the other knee you're making bigger cuts, you're damaging the ligaments a little bit and it's harder to balance that afterwards. It's not going to do as well and we tell you that common sense wise. In a real time every study shows that and one of the common things we see in this day and age there is a lot of young physicians out there who are hungry there's not enough joint surgeons in the world to do all the joints so we have younger guys who are trained in other things with the new techniques trying these things and there's a lot of things happening because you're not trained to do this. And if we can come up with technology to make them better surgeons which I think this is patients the will do better.

It takes all of the guesswork out of it.

Dr. Buch: Exactly, there is no guesswork on this.

You don't have to guess.

Dr. Buch: No, you learn to, when I first started using this technology I still measured cuts. I would say okay let's make sure, let's make sure we're not taken off too much, less make sure this is right. Now I never have to worry about this.  It is precise almost every time, we just make our cuts.

The only thing that could be wrong and I imagine this is very important, is that if somebody got the wrong box.

Dr. Buch: Correct, but it is just like anything else,  you don't give wrong blood there are double checks for those things, we have the same checks with these. You would know right away when you went in there if it matched their knee or not because it would not fit.

What else do you think we've got it covered?

Dr. Buch: We covered a lot. Most of the people that see this are not the doctors they are patients. They are not so big in technology they just want to know is it good or is it bad. Am I going to walk again not walk again, am I going to hurt and not walk again? What can and can't I do that is basically it. Most do not listen to this kind of stuff. We have to explain it in a way that patients understand. If I take your knee and build a knee that matches your exact original knee it should do better than me trying to balance it with some other knee.

Yeah I think just the idea of what's better making my knee fit your product or making your product fit my knee. That's common sense right there.

Dr. Buch: Every person has built something that did not quite fit, but you make it work to best of your ability.  This is what you are doing with a standard knee replacement. With this technology you do not have to do that, you know before the surgery they fit perfectly together, they will match the patient.

And it's not just that you listen to your patients you actually are a patient yourself.

Dr. Buch: Correct, I have gone through what they are going through. When a doctor tells patients that what they can do on their knees or hips, is an educated guess because that is the norm or how they were trained. I have done all of these things. I have run on my knee to prove you can run it. Now do I want you running on it forever no, but I did a mini marathon on it. I ski on it and prove these things can be done; you can live an active life. The other thing is I have been through both sides of this, I went through the old way of doing things with my one joint and I was in the hospital for three-four days. It was a little more sore and painful, I then went through the new technique with the other one and I was out in twenty-three hours because they would not let me leave sooner. I was up walking in the hallway, climbing up and down stairs in no time at all with the newer techniques. So I have felt what they are going through, I can tell them what to expect and what's going on. I can better understand where they are at in the process and explain it to them. We no longer use these old techniques. We have taken leaps in technology because now we can get patients out of the hospital with fewer complications quicker.

I guess you had the hip done the old way and the knee done the new way?

Dr. Buch: The process is the same whether it is a hip or knee it's the same thing, there is still a joint the process is the same. Actually hips are quicker than knees to get through yet it was still three or four days with the hip using the old standard techniques compared to the new one. With the knee, this knee I was in the hospital for three to four days.

So if you compare the old to the new just on yourself.

Dr. Buch: My patients were leaving the hospital well before I never did and I am stubborn, tough as nails,  and I was still in three or four days. It took me six weeks of walking around with crutches or a cane to get around. This was because the old techniques of longer incisions, old cutting devices, and surgeons stretched things out. It swelled more, it bled more, and I had to go through this process numerous times. It did not feel like my knee for over three months. This day and age most of my patients come in and they are walking with nothing within two weeks. Half of them are going home the same day or the next morning. This is a giant leap in technology to allow us to do this.

So are you still skiing?

Dr. Buch:  Yes, I do still ski.

I see a picture of skiing over there is that one of your kids?

Dr. Buch: Yes, I have to chase after those guys. They are all grown up now and so when I was younger I had to keep up with them even with bad knees, chasing them down the slope in pain was no fun. But I had to still ski, my kids love to go ski and I didn't believe that you would be able to do that again with a total joint until I found two patients both of them were seventy years old that were skiing. Both patients had bilateral knees or both knees replaced.  They said no it is no problem at all if you skied before. A doctor told us not to do it and back then we told you not to ski, but what we discovered as technology improved we allowed you to do more. With the new technology because I am not cutting as much bone and I am saving more of your soft tissues. This allows you to go back and do almost anything. We used to tell you, you can do eighty-eighty five percent of what you used to do, maybe ninety percent. About ten-fifteen percent you could not do. Today it is maybe five percent or less of things we recommend you not doing. That is a big leap in what you can do and can't do. I let you do anything you want to do, on your knee as long as it does not hurt. Most of them do what they want to. I have plenty of people run on it. I would prefer they do not run on it because it is a machined part that will come loose sooner the more you use it. But if they are happy and they are able to get around I let them do what they want.




KNEE REPLACEMENT: With the knees being the body's largest joint, it's important to take care of them, but sometimes normal wear and tear can take a heavy toll on knees and surgery may have to be performed. Knee replacement surgery typically takes place after damage from an injury or arthritis. The surgery is a safe step to take after medications and physical aids may no longer be of use. Knee replacement surgery was first performed in 1968 and has evolved into a common and successful form of treatment for knee pain, with approximately more than 600,000 knee replacements performed each year in the United States.  (Source: orthoinfo.aaos.org)

CAUSES: Knee pain can be caused by many different problems. There are a number of injuries that can affect different parts of the knee like the ligaments, cartilage and tendons. An ACL injury occurs when the anterior cruciate ligament, one of the knees four ligaments, tears and often happens in athletes when they change sudden direction. Tendinitis is another form of injury that causes irritation and inflammation in one of the knees' primary tendons. Injuries aren't the only reason you may need knee replacement; there are many forms of arthritis that often cause the knee to be replaced. Osteoarthritis is the most common form of arthritis found in the knee and mostly occurs in the elderly after the cartilage in the knee has deteriorated.  (Source: www.mayoclinic.org)

NEW TECHNOLOGY: 3D printers are emerging as an effective way of producing materials for many different functions and are now being utilized for medical purposes like the 3D knee. In the past, the parts for knee replacement surgery caused pain and didn't always form well to the needed area. With the new 3D printed replacement knees, pain is reduced and the perfect fitting knee can be created. The newly printed knees fit the patient naturally which makes it much more comfortable compared to ordinary replacement knees which come in different sizes that are pre-determined. With the new 3D knee, patients are given a total knee replacement and sent home the same day.  (Source: Dr. Richard Bush)



Richard G. Buch, MD

Orthopedic Surgeon

The Dallas Limb Restoration Center

Phone: (214) 208-5500