Lenghtening Legs: Precice is Precise

By Gwyn Bevel | gbevel@kfdx.com

Published 08/07 2014 03:54PM

Updated 08/07 2014 05:42PM

Imagine if one of your legs was longer than the other? It might not sound like a serious problem, but it could lead to severe hip or back pain if not treated. Now there’s a new way to permanently lengthen limbs.
College student David Pfeiffer lived with a painful problem for 12 years. When he was seven he broke his left leg. When it healed, it grew one-inch longer than his right.
“I was walking around with one leg longer than the other. It was causing back problems.” Pfeiffer told Ivanhoe.
Patients like Pfeiffer used to have to wear a painful external device for months. Pins pierced the skin and muscle to literally stretch the leg.
With the PRECICE limb lengthening system, a titanium rod with a magnetic motor is internally implanted in the patient’s leg bone. An external remote control activates the magnets inside and gradually pulls the bone apart.
Dr. John Herzenberg, a Pediatric Orthopedic Surgeon at Sinai Hospital in Baltimore, is glad to see this new procedure.
“No longer do my patients have to be condemned to wear this bulky medieval torture device outside their leg. This is what we’ve been waiting my whole professional career.”  Herzenberg told Ivanhoe.
After 25 days of treatment, Pfeiffer’s leg grew one-inch. Now he can stand tall without any pain holding him back. 
The device is capable of lengthening up to three inches and can be used multiple times if needed. If the patient’s leg is too long they can also reverse the effects by turning the magnets in the opposite direction as long as the bone has not healed.
So far, Dr. Herzenberg has used the system on about 100 patients. He says people from all over the world have traveled to his center to have this procedure.

FEMUR AND TIBIA: When there is a crack or fracture in one of the leg bones, it is considered broken. Bones in the leg that are commonly broken are the femur and tibia. The femur is the longest bone in the body and is the connection between the hip and tibia. The lower part of the leg is made up of the tibia or shin bone, and connects with the femur down to the ankle. Common causes for breaking the tibia include auto collisions and sports injuries. In these instances, the tibia can be forcefully twisted, causing a possible spiral, stable or traverse fracture. (Source: http://orthoinfo.aaos.org/topic.cfm?topic=A00522)
TREATMENTS: When dealing with a broken leg, there are many different treatment options depending on the location and severity of the break. The most common form of treatment for minor fractures is plaster cast which holds the bone in place for an extended period of time, allowing it to heal. Painkillers are often prescribed in addition to a cast or splint. If the bones become misaligned during a break, then a surgical treatment is performed known as closed reduction which pulls the bones back into place. The most severe fractures are treated with surgery involving wires, plats or screws. (Source: http://www.nhs.uk/conditions/broken-leg/Pages/Introduction.aspx)
NEW TECHNOLOGY: A new procedure is now making it possible to permanently lengthen a leg. The PRECICE limb lengthening system implants a titanium rod with magnets into the patient’s femur or tibia. The patient then uses a remote control several times a day for a few minutes to command the magnetic rod to slowly pull the bone apart. This pulling apart allows for new bone and tissue to gradually be grown at approximately 1mm per day. The PRECICE procedure is used for leg deformities from birth or injury and is expected to reduce infections during the healing process. (Source: http://www.llila.com/precice-limb-lengthening.php)

Helene King
LifeBridge Health


John Herzenberg, M.D., Orthopedic Surgeon with a specialty in Limb Lengthening and Pediatric Orthopedics and Director of the International Center for Limb Lengthening at Sinai Hospital of Baltimore.
Can you tell me a little bit about David and tell me why one of his limbs was longer than the other?
Dr. Herzenberg: Right, David is a 19-year-old guy from Maryland and when he was seven he was discovered to have a cyst growing in his left thigh bone. The doctors treated that when he was seven years old but the treatment somehow stimulated that left leg to grow too long, so the left leg was about an inch longer than the right. He lived with that for his entire teenage years and then at the age of 19 he got kind of tired of it because he was limping up and down. I have an x-ray that shows David’s long leg, the left one that had the cyst in it, and his normal leg which was shorter. It’s a bit unusual because the one that is involved is longer, not shorter. On this x-ray you can see that David’s knees are at different heights. Because the left leg grew too long it was stimulated by the bone cysts and all the surgery that was done to it when he was seven years old. The right leg is his normal leg, but because the left leg grew an inch too long the right leg is an inch too short, and this creates a problem for him. You can imagine if you take one shoe off and one shoe on and walk around like that, that’s what life is like for David before his surgery, before our leg lengthening surgery. It’s not very comfortable and after years of walking like that you start to develop back pain and hip pain. You can wear a shoe lift as one way to compensate for it.  This is an x-ray made with him on a shoe lift so his hips are level but the knees are different heights. Most young people don’t want to wear a shoe lift the rest of their life, so we have other options for them.
What are the other options?
Dr. Herzenberg: Well, for the past 25 years or more we’ve been using great big devices like this. This is an external scaffolding that goes around the leg and this is a femur bone. We cut the bone, assemble this outside scaffolding and attach it to the patient with pins that go through the skin through the muscle. This is kind of the old technique that we used for years. As you might imagine, wearing this on your leg for four, five or six months would not be a very pleasant experience.
Is his left leg weaker than the right leg because of this?
Dr. Herzenberg: No, in fact the left leg that’s been lengthened is going to end up being stronger. If you look, you can zoom in and look at the new bone that’s forming. This is actually wider in diameter than the native bone. The native bone is his normal bone and this new bone is forming this voluminous kind of pouched out mass of new bone. That’s actually going to be stronger and more resistant to fracture than his native bone. Over time, that may kind of shrink down and become more normal looking inside. This isn’t so hugely large that it’s going to be palpable or you can’t feel it from the outside. It makes very strong natural healthy bone, it’s not artificial. It’s not like hip replacement or knee replacement where you’re left with a metal and plastic hip that may or may not last, may wear out, or may get infected. This is native healthy bone and it will last forever.
So this is kind of a huge deal.
Dr. Herzenberg:  Yeah, this is. When I see patients and I talk to them about this I say you could have this or you could have that, which do you want? Do you want to have the old device or do you want to have the new device? The new device you can’t see because it’s deep inside the bone. The old device, the whole world sees because it’s outside your leg. It’s got pins that pierce your muscle and your skin and it’s really annoying. For that reason, we feel that this new intramedullary system is a real game changer and this has really been an important advance for our patients.
Dr. Herzenberg: This is a special model that’s designed for demonstration purposes. It goes in and out and in a regular model.  This is one that we’ve taken out of another patient and cleaned up. I can’t piston in and out because it’s got the internal mechanism. This is one that’s had the internal mechanism removed so you can see the pistoning. But this is the actual device that goes in and it’s only activated by applying the magnet. You can see that it’s doing something to that magnet inside.
How big of a breakthrough do you think this is?
Dr. Herzenberg: This is what we’ve been waiting for my whole professional career. For the past 25 years I’ve been putting these external fixator’s like this on children and adults and we did it because that’s all we had, but we knew all along that what we really wanted was an internal device. It was just a matter of waiting until the technology caught up to what we wanted. As a sort of intermittent step between – before we had this technology of the magnetic motor we used to try to save some time for the patient by putting a nail in. You can see where they put a nail in this bone. The advantage of this technique was so we could go back and put the locking screw in at the bottom and then take the fixator off early before the bone was healed in. So instead of waiting for the full time for all this to heal in with healthy solid strong bone, we could remove the device after we finished the lengthening. This one the patient would wear maybe for two months instead of six months. But this one they would wear for no longer than six months. So for many years we used this method as a sort of stop gap measure. This is not a lengthening nail, this is just a nail, the same we use for traumas. It’s solid with no male and female pieces that piston, no motor, nothing inside. But it was just to act as a stent to hold this apart. We did this for the past 10 years or more but all along we’ve been hoping for the technological breakthrough that would give us this technology of a pistoning nail that is controllable and can go forward and reverse and under precise control that will allow us to be very accurate in how much we lengthen, how fast we lengthen, or how slow we want to lengthen. I’m just happy that I’ve experienced this in my career and that we now have much better things. I don’t have to scare my adults and my children with these things and tell them you have to wear this on your leg. We can tell them we’re just going to implant this through a one inch incision in your upper thigh and it will do all your lengthening.
It’s only for the upper thigh?
Dr. Herzenberg: No, it’s actually designed for the upper thigh, the femur, but it’s also designed for the tibia, the shinbone. We have probably in our series 175 that have been put in the upper leg but 25 have been put in the lower leg. We have some patients we even put in upper and the lower leg simultaneously. There are some patients that also get both upper thighs simultaneously.
Is there anything else you want to add?
Dr. Herzenberg: No, just happy that you came here to spread the word. I guess by truth in advertising I should mention that myself and my partner, Dr. Shawn Standard, were part of the physician development team that helped the Ellipse Company which is out of Irvine, California to develop the PRECICE nail. I know that’s a misspelling. It should be S, precise with an S, but its PRECICE with a C because someone else had the trademark precise with an S.
Is that all caps?
Dr. Herzenberg:  It’s all caps. PRECICE with two C’s, all caps and the company is Ellipse Technology in Irvine, California.
Dr. Herzenberg: There are achondroplast kids who are going to grow up to be about four foot three inches tall, about the height of a third grader. For them, it’s not just a cosmetic issue but also a functional issue about being able to get around in society and reach things and drive a car without pedal extensions and reach a buffet in a restaurant or something like that. There are a million things that come to mind that are hard to do when you’re really short and for the dwarf population we do offer bilateral or both legs lengthening. It’s not to treat inequality but to make them longer and more functional.
But most insurance covers it for non-cosmetic reasons?
Dr. Herzenberg: Right, we have not had trouble getting the insurance to cover it. It’s a little bit more expensive than the external apparatus, but when you take into account lower complications, and a lack of infections from the pin sites that are exposed to the bacteria, I think in the long run it’s actually more financially desirable to have a slightly more expensive device that doesn’t go through your muscles and cause problems with your knee and hip.
So the old device, the huge cage you showed me that can cause other problems?
Dr. Herzenberg:  The cage device is removed once the bone is healed but that’s the problem is it sometimes takes a long time for the bone to heal fully. Wearing that cage on your leg for a long time is really inconvenient, unsightly and uncomfortable. The other problem with the cage device is that the pins penetrate through the skin and go into the muscle and into the bone. It’s very common at some point during the three, four, five or six months you’re wearing it for one of those pin sites on your skin to become infected and that infection can theoretically spread and will go down to the bone and cause a deep bone infection. When these are implanted you’re not exposed to the outside world. There’s no communication between the skin and the bone or the nail itself. And so it’s much safer in that regard.
You said earlier when people have a shorter limb that it could cause back pain and hip problems. Can it lead to more serious problems like a hip replacement?
Dr. Herzenberg: Our patients that have limb length discrepancies throughout their lives, eventually it catches up with them. They may do well as a child but when they get to be adults and a little bit bigger and heavier, they’re walking on uneven legs all the time and they start to develop hip problems, even the opposite hip can become a problem and they develop back problems. If these are left untreated for a long period of time, these problems can become permanent. What we typically tend to see are adults who have a limb length difference that may be a 1 inch or two and when they are younger their parents tell them they have to wear the shoe lift that the doctor prescribed. When they get to be teenagers they get their own mind and they don’t want to wear a shoe lift, they don’t want to look different than the other kids and they prefer to limp and to move up and down or twist their back when they stand and that’s when they run into problems long-term. We have good solutions for them now and solutions that are cosmetically acceptable. They no longer have to wear the external fixator, the cage around their leg for long periods of time. For very young children we operate on under the age of seven, we still have a need for this cage device. Certain other conditions where this may not be suitable, we still use the other device but we’re using a lot less of the external frames and a lot more of these internal devices now.
What other conditions?
Dr. Herzenberg: We treat everything from birth defects in little tiny two-year olds to adults who have bone infections after trauma, motorcycle accidents, and sometimes they’re missing bone and we have to shorten the bone to get it to heal then come back later and lengthen them. There are literally hundreds of different scenarios where we can employ these techniques to try to improve things. The other group of patients we treat are patients that have bow legs, crooked legs from either rickets or vitamin D deficiency or other congenital problems or metabolic diseases and they also can require not only straightening but also lengthening.
You mentioned earlier that after you have a procedure done you really shouldn’t be walking on it, do they have to wear crutches?
Dr. Herzenberg:   What you’re not seeing inside is a very delicate mechanism with three planetary gears, a small magnet the size of a AAA battery and a threaded lead screw that turns. And this mechanism is a little bit delicate so if you were to take this and pound on it you would break the internal mechanism. The patients are instructed that they are not allowed to put their full weight on it on a regular basis until the bone is healed. The patients do have to use crutches; they have to protect it and have to do lots of physical therapy. This has been a huge improvement for the patients in that they don’t have to wear the frame but there are still many other factors involved in limb lengthening that make it a challenging process. We cut the bone and lengthen the bone and you can see where the bone has been cut, it’s pulling apart but we don’t cut the muscles. The muscles have to stretch which requires a lot of physical therapy, stretching and splinting. There’s still a very serious commitment that the patient has to make to undergo this process.
When do you think David can get back to doing MMA and running?
Dr. Herzenberg: David has been a really fast healer. Young kids heal quickly under the age of 20 so at three months he already has a lot of bone in there and at three months we released him to walk without crutches. He used his crutches for about 10 weeks during the three month part. The 12 week part he was off crutches. We’re going to let him go back to sports next month when we see him.
What happens if you accidentally lengthen it too much?
Dr. Herzenberg:  That’s a really cool question because there are other devices around the world that work on a different mechanism. They may have a ratchet internal mechanism where the patient has to twist their leg to activate it. There’s one in Germany that has an electric motor. But of all the devices that are available in the world this is the only one that can go forward or reverse. It’s a very simple process, so let’s pretend this is the leg that’s being lengthened and the patient puts the device on and activates it. Let’s say they go too far and they’ve lengthened it 25 millimeters instead of 30, what do you do? Well it’s very easy as long as the bone hasn’t healed yet. We simply tell them to turn the device backwards and this will make the rod get shorter. It’s pretty cool and we sometimes use that as a technique to make the bone heal faster. We will intentionally over lengthen it a little bit, maybe a quarter of an inch and then go backwards and compress it. That compression causes the bone to heal faster. This really gives us very absolute and precise control over the lengthening process. If we want it to go a millimeter a day we do a millimeter day. If we want to slow down to half a millimeter because the bone is not forming well, we have the option of doing that. It’s just a matter of how much time they place this on.  We can go forwards and backwards, faster or slower, and this gives us the control over what’s happening inside the leg to a very high degree of precision.
Does it make a tighter honeycomb structure in the bone?
Dr. Herzenberg: We sometimes go intentionally or sometimes unintentionally too long. When we bring it back, the new bone segments that form the last part to heal, is the part in between.  That can get too wide and if you squeeze them together they heal faster. You get more enter digitation of the bone and it makes the whole process speed up.
What is the longest you had to lengthen someone’s bone?
Dr. Herzenberg: Oh, yeah what’s the indoor record for limb lengthening?
Dr. Herzenberg: That’s a really good question because let’s say you take someone who’s a dwarf and is four foot three and you’d like to make them five foot two, that would be like 11 inches of lengthening. This device is not capable of lengthening 11 inches but it’s capable of lengthening up to 3 inches so it’s like the old African proverb, how do you eat an elephant? Just one bite at a time. If you say you want to do 11 inches you can’t do 11 inches all at once. Not only would the bone not tolerate it but the nerves and the muscles would not tolerate it. So what you have to do is you have to pick two or three times during the child’s life, maybe at age 10, 12 and 15 where you do these treatments again and again. You may do 2 to 3 inches at age 10, another 2 to 3 inches at age 12, another 2 to 3 inches at age 15. The total will give you that nine or 10 inches. For the first 25 years of my career we used devices like this to lengthen a leg. This is an external scaffolding that gets built around the patient’s leg and is attached by these pens that pierce the skin, the muscle and actually driven into the bone. This scaffolding will lengthen once you cut the bone and the patient turns the nuts here and makes the leg get longer. The problem is having to wear this on their leg for four months or six months at a time and as you might imagine this is not a very comfortable thing. For the past 25 years we’ve been wishing and hoping that we could develop something that would be internal like this. Where a rod goes down in the center of the bone you would cut the bone and the rod would somehow magically lengthen. That magic now exists and that magic is this device. The real magic of all this is this little magnet that’s inside. The question is how do you power that? How do you turn it on and off and make it actually move. This goes outside of the body and is magnetic. If I take one of these rods you can see the magnet. You place this magnet device over the nail and activate it. There are rollers in here that are magnets which create a field that causes the magnet inside to turn. As these turn it’s causing the magnet inside to turn and it slowly, lengthens the leg. The patient puts this on their leg for seven minutes a day. If the patient does this for seven minutes each day the leg would get longer by 1 millimeter which is very small. David needed 25 millimeters or an inch, so a millimeter a day is 25 days. For 25 days in the month of February he was turning this seven minutes a day. Actually to be a little bit more specific we had him do it two minutes four times a day so it was about eight minutes a day. We like to break it up into gradual steps. This has been a real game changer for us. Instead of having the big, bulky external frame on your leg the patients have this very deep inside. This concept of having a nail in your leg, in the thigh bone or the shin bone is not new. If you were in a car accident and you were brought to any hospital in America they would put a similar device in your thigh bone or in your shin bone to fix the fracture. The difference being though this one has the pistoning effect in the motor and the magnet and the gears inside, whereas the one we use for trauma is just a straight nail with no fancy insides. That’s what we’re capable of doing now. This has completely changed the way I practice my specialty of limb elongation. No longer do my patients have to be condemned to wear this bulky medieval torture device outside their leg for four to six months at a time. They’re much more comfortable if they have this inside the bone where you can’t even see it unless you take an x-ray because it’s buried inside the bone. Speaking of x-rays, this is what it looks like and this is David’s short right leg. He’s facing you so this is his right leg, the nail is inside. You can see where we cut the bone and this is the day of surgery. There’s also these cross bolts to hold it and the nail is going to piston out so that after a few weeks of turning you can start to see the bone separating.  Now the bone is getting longer, this is after maybe two or three weeks of turning. Here’s where the bone is separating after a few weeks of turning. The patient can’t put his full weight on it until that separation fills in with healing bone. After three months you can see the two legs equal and the gap that was just full of a dark space now has white fluffy bone in it. As this bone matures he’s allowed to put his full weight on it. By three months he can be weight bearing without crutches or a walker and after one year we go back and take this nail out so he doesn’t have to have that in his leg the rest of his life. This bone that we make here is natural human bone that functions just like any other bone. In the end he’s left with no metal, no abnormal artificial materials in him. It’s just him and his new bone.
I know his was a cyst, what about other patients?
Dr. Herzenberg: We have broad categories of two types of patients that we treat. One is children with birth defects, you know they’re born with a leg that’s short for whatever reason and these can be devastating because the leg can be not just an inch short but three, four, five or six inches short. The other group of patients we have are adults who are injured in accidents and the bone may heal short. The bone was crushed into a million pieces and when the doctors got it healed it ended up being too short. They don’t have to suffer with a short leg even though it’s healed.  The adult patients tend to be mostly after an injury, the children tend to be mostly birth problems.
How long do you have to have the pin in your leg?
Dr. Herzenberg: The pin that we put in there, this intramedullary device is the technical team term and this one’s called a PERCICE nail, that’s the name that the company gave it. This only needs to be in the leg as long as the bone is healing. Once the bone is healed it can come out. It could theoretically stay in your leg forever but since this is a new device and we’re not sure what the long term effect, especially in a child would be, we recommend removing the device.
How young can a child be to get it?
Dr. Herzenberg: In our practice half of our patients are below age 18 and the other half of our patients are over age 18. At this point in time we’ve implanted over 100 of these and have been using it for just over two years. In the pediatrics group I can’t go much younger than seven and a half years old for technical reasons because the size of the bone has to be a certain size to accommodate this type of PERCICE nail. In adults we’ve gone up to the 50’s and even 60’s. There’s really no limit on the upper end for adults. On pediatrics there’s a little bit limit because of the size and the location.
Now from what I understand you have treated patients in every continent.
Dr. Herzenberg: We’ve been around for a long time and call it the international center for limb lengthening. We do treat patients that come from all fifty states and basically every continent except for Antarctica. So we have patients that routinely come in from the Middle East, from Europe, and from the Far East. We had one woman come from China to be made longer. We put nails in both of her legs to make her a bit taller and she went back to China and got a good job.
So this can be done for cosmetic reasons too?
Dr. Herzenberg:  Yes this can be done for cosmetic reasons but we don’t recommend it on a routine basis because it is a very difficult and expensive process and insurance will not cover it for cosmetic reasons. The one group that you may think is cosmetic (but is not) is the group with dwarfism. Classical type of dwarfism would be achondroplasia.


If you would like more information, please contact:

John E. Herzenberg, MD
International Center for Limb Lengthening
Rubin Center for Advanced Orthopaedics
Sinai Hospital of Baltimore

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