Transcription:
Nail Insertion to Address Limb Length Discrepancy

Melanie Cole (Host): At UVA Children's Hospital, orthopedic surgeons encounter a variety of congenital conditions that affect a child's mobility and they stay abreast of the latest technologies and procedures to provide patients with greater options. My guest today is Dr. Mark Romness. He's an orthopedic surgeon who focuses on the treatment of children with musculoskeletal problems at UVA Health System. Welcome to the show, Dr. Romness. What is leg or limb length discrepancy?

Dr. Mark Romness (Guest): Limb length discrepancy is really a fancy medical term for unequal leg length or someone that just has one leg that's longer or shorter than the other one. That can be from multiple causes. Sometimes, there are even some birth conditions where one leg doesn't grow as rapidly as the other. The other area we usually see it is from previous trauma or injury to the child's growth plate in the bone leading to growth abnormalities in the bone and that ends up in one leg being either longer or shorter than the other leg.

Melanie: Is this something that's very obvious or would the child start to experience some pain in walking, or can you just really see it?

Dr. Romness: It's usually not painful and it can often start out as something very subtle, which is maybe a quarter or a half inch difference in their length but as the child grows, that discrepancy or difference in leg length can get worse and so it's fairly related to the age of the child. So, the younger the child it's more hidden, but it's also a higher risk in chance that it might cause more problems down the road.

Melanie: If someone comes to you and their child has this discrepancy, do you start with things like you know, lifts for their leg or for their other foot or do you go right to some interventions?

Dr. Romness: Generally, a lift is not absolutely required. Everybody thinks that having a little bit of difference in leg length is going to affect your legs, your hips, your spine, cause back pain, but there's really no data to support that. And, the other thing is, just small differences don't make that big of an effect, mainly because we're rarely standing on both legs at the same time. But, it's really the more dramatic differences--once you get up to closer to an inch or more--that you'll actually start to see a significant limp. It can also even affect your energy efficiency walking once you get up to about one or two inch difference.

Melanie: Are there some complications from not addressing this issue?

Dr. Romness: I mean, again, shorter or smaller length differences can be compensated just by the body or with a simple lift in the shoe, but once you get up over an inch or once you get into the two to three inch range, then it really throws off the dynamics of the body and you're better off addressing it with more equalization procedures.

Melanie: So, tell us about some of those equalization procedures--the PRECICE® nail insertion.

Dr. Romness: Sure. When you're dealing with two legs that are unequal, I often simplify it and say that you can either shorten the long leg or lengthen the short leg. In a growing child, sometimes we can have the leg stop growing early so that the other leg can catch up, but the other way to do it is to lengthen the short leg. The way we do that is make a cut in the bone and gradually separate the bone at about a millimeter a day. Traditionally, that's been done with sort of external fixation, or ring devices on the outside of the leg but, more recently, there's been a new technology where you can actually lengthen with a rod that goes down the inside of the bone and that way nothing is outside.

Melanie: So, tell us about that procedure. So, this is a surgical procedure for a child. Is it something that stays in permanently? Is it temporary? Tell us about it.

Dr. Romness: The rod itself goes down the middle of the bone. It's usually only for sort of the older kids that are close to done growing, but it's an excellent internal device that you can control the lengthening carefully with. Once the bone is out to length and healed, we usually do recommend that the rod come out, just because if it stays in there too long, it can be very difficult to get out.

Melanie: So, you can actually control this rod from outside the body as this child grows? I don't mean to be simplistic, but something like braces in a child's mouth that changes their jaw structure. Is that what this is like?

Dr. Romness: It's similar. Again, it's a rod that's distracted using magnets. So, you have an external drive device that the patient positions on his or her leg and they can control how much the rod distracts. We usually do three distractions a day at a third of a millimeter a day, so you're actually lengthening the bone at one millimeter per day.

Melanie: Is this painful for the child?

Dr. Romness: In general, no. You know, with a simple straightforward distraction, it's relatively pain-free after you're over the initial surgical procedure. It's partly because the distractions are so small. You're looking at one-third of a millimeter per distraction, so the stretch on the leg is usually not that painful.

Melanie: Do they have a problem going through security in airports? What is it made of?

Dr. Romness: I don't know the exact metal, but because it's deep and implanted, it rarely sets off metal detectors.

Melanie: Wow. That's fascinating. How long do you leave it in?

Dr. Romness: It's usually about a year or two until it's taken out. The lengthening process takes, again, as I mentioned, you're actually lengthening it one millimeter per day, but then you also have to wait for that bone to heal, which takes a little bit longer. On average, a true healing is about one month per centimeter of lengthening. So, if you're looking at an inch of length, that's about two-and-a-half to three months until the bone is well-formed and strong.

Melanie: So, when the child is done using this device, then the ossification of their bones, is that affected? When you take this out, what goes on inside their bones? Are they still able to grow?

Dr. Romness: Yes, because during the lengthening procedure, you're lengthening toward the middle of the bone, whereas most of the growth comes from the ends of the bone.

Melanie: That's absolutely fascinating. Are there any drawback to it?

Dr. Romness: I mean, with the lengthening procedure, you are concerned about developing contractures in the joints above and below the bone, so that does need to be monitored carefully during the lengthening process. You also have to be careful with your lengthening rate, that if you lengthen too quickly, you'll stretch all the surrounding soft tissues, including the nerves and blood vessels whereas if you lengthen too slow, the bone will form too quickly and then it will actually heal too quickly and you won't be able to keep lengthening.

Melanie: The surrounding soft tissue was going to be my next question, Dr. Romness, so you answered that. Tell us about some stories and the effectiveness of these treatments--the patients that you've helped that would benefit from this approach. Are they older? Teenagers? Tell us about and give us some of your examples.

Dr. Romness: For this procedure, they need to be close to done growing, so it's usually a teenager where the bone is nearly done growing for the rod, but you can still do lengthening procedures with the external device on the younger kids. The case I think of most is a kid who has been through two lengthenings. He went through one lengthening with the external rings and then, more recently, he went through a lengthening with the internal rod and both the patient and his mother were just ecstatic about how much easier it was the second time.

Melanie: And, what is the child's life like with this device inserted? Are they banned from athletics? Do they have trouble walking? What goes on there?

Dr. Romness: Well, during the initial healing phase, the first week or two, they are on limited activity. It's kind of like when you break your bone, they have to take it easy on it. During the distraction phase they have to be somewhat careful, so we keep them out of sports, but they're able to go to school. And then once the bone is fully healed, it's back to all activities.

Melanie: So, wrap it up for us, Dr. Romness. What an interesting topic this is--about the PRECICE® nail insertion to address limb length discrepancy. Tell people listening what you really want them to know and why they should come to UVA Health System for their care.

Dr. Romness: Well, I think it's an excellent opportunity for state-of-the-art technology and I think UVA has been good at keeping ahead of pace with this type of activity and keeping what's best for the patient in mind.

Melanie: Thank you so much for being with us today, Dr. Romness. We'd love to have you on the show again. You're listening to UVA Health Systems Radio. For information, you can go to www.UVAhealth.com. That's www.UVAhealth.com. This is Melanie Cole. Thanks so much for listening.