Doug Brayton, a lieutenant commander in the U.S. Navy in Norfolk, Virginia, says he first noticed his left leg was shorter than his right when he was in college. It seemed minor then, and he thought he’d just have to live with it.

But in the years since, the limb length discrepancy — a term that’s also used to describe when a person’s arms aren’t of equal length — eventually led to inflammation and a burning pain in Brayton’s hip that he dulled with medication. “It was just a constant pain,” says the 35-year-old. He also dealt with occasional severe bouts of back pain from the one-inch leg length discrepancy.

Even a centimeter’s leg length difference can affect how one stands, walks and is able to move around, let alone the personal expectation and desire for symmetry many people have. People who have more significant limb length discrepancies also tend to spend more time on the long leg and put more weight on it. “Over time that leg often will wear out faster — that’s something called long leg arthritis,” says Dr. John Herzenberg, director the International Center for Limb Lengthening at Sinai Hospital of Baltimore and a clinical professor of orthopedics at University of Maryland Medical School. “The other thing people do is if they’re holding their pelvis crooked and their back crooked because they have one leg [that’s shorter], then over time a lot of them will develop back pain and hip pain and leg pain from being off-kilter.”

[See: 13 Things to Know Before Your Hip Replacement.]

Brayton eventually saw a podiatrist who gave him a lift that went into his tennis shoes or combat boots that corrected the discrepancy. About a month after he started wearing the orthotic, he says the pain went away. But when he took off his footwear, the pain would return. “I would walk around on my left tiptoe,” he says. That, and the success of the orthotic, led him to seek a permanent solution; and he was referred to Herzenberg.

Brayton thinks the discrepancy is congenital, though he didn’t notice it until later, and he doesn’t trace it to any particular condition. Limb length discrepancy can be the result of a congenital issue, like hemihyperplasia — wherein one side of the body grows more than another. Or it can be “acquired,” like when a person breaks a leg and the mended bone heals short. Various factors may be considered when deciding how to address the discrepancy, in addition to how big it is. For instance, clinicians would need to consider whether it’s progressively getting worse — as in the case of a child whose growth is increasing the limb length inequality — or if the short leg, or a bone in that leg, is also crooked. “Treatment has to be individualized,” Herzenberg says.

For many, a difference in limb length is so minute as to hardly be noticeable and doesn’t warrant treatment. “It is not unusual for an individual to have a small limb length inequality, and it’s thought to be negligible for most,” says Dr. Francois Lalonde, a pediatric orthopedic surgeon at CHOC Children’s Hospital in Orange, California.

In others, with a discrepancy of up to two centimeters, a shoe lift may be recommended. For a more minimal discrepancy in that range, a heel wedge inside the shoe may be sufficient, Lalonde says; but for a discrepancy on the higher side of that range, an external lift on the bottom of the shoe is typically needed.

However, especially where the discrepancy is more pronounced — and this is monitored both through regular measurement and predicted in patients who are still growing, and whose leg length difference is expected to increase — clinicians talk to many patients and their families about permanent surgical solutions. These essentially fall into two categories: shortening the longer leg, or lengthening the shorter leg.

In growing children, for example, a procedure called epiphysiodesis may be performed to stop growth by operating on a growth plate in the longer leg, to allow the shorter leg to catch up. In adults, who aren’t growing anymore, it’s possible to take a segment of bone out to shorten the longer leg. If the discrepancy is really small, it’s easier to shorten the long leg, Herzenberg says. However, experts say, particularly for those with bigger discrepancies of several inches, this isn’t optimal, or may not be appropriate; and many adults as well as children or their parents push back against surgery that would make them shorter. In general, “It’s getting challenged more and more by parents who want their children to be as tall as possible,” Lalonde says.

[See: What Are the Types of Orthopedic Doctors?]

Traditionally, the alternative — limb lengthening — has been done using a process called external fixation. That uses an external apparatus, like a scaffolding that’s built outside the leg, which connects to the bone through the leg with thin wires or pins that pierce through the skin, muscle and bone. “We make a cut in the bone and then that cut will start to heal, but before it gets a chance to heal we activate the external scaffolding device to stretch it out and make it go at a rate of about a millimeter per day,” Herzenberg says. “We get good results, but we don’t like the fact that our patients have to wear this bulky uncomfortable scaffolding that has pins and wires that pierce through their skin,” or what he alternatively describes as a “painful, medieval torture-looking device.” The infection rate is also high — almost all patients get infections at some time from the wires and pins, he says; antibiotics usually take care of those. “But it’s a nuisance, and occasionally you get a deep infection.”

More recently, Herzenberg was involved in the development an internal fixation option, using what are called PRECICE rods that can be inserted into the bone and are designed to lengthen the femur or tibia. He is a paid consultant for the San Diego-based medical device company, NuVasive, that makes the devices. The firm also owns a similar technology, called the MAGEC system, used to straighten the spine in some kids with severe scoliosis who are still growing.

Like that system, PRECICE rods can be lengthened using magnets applied to the child’s body. With PRECICE rods, however, that lengthening is done not every several months in a doctor’s office like with the MAGEC system, but on a regular basis in the home. “We teach families how to put it on. It’s very easy,” says Lalonde, who also implants the rods. A marking is made on the skin indicating where the magnet should be placed, and the patient applies the device over that marking for typically a few minutes at a time, he says.

The lengthening is done slowly, at up to a one-millimeter-a-day pace — and even that can be a literal stretch. “That’s usually the maximum we go,” Herzenberg says. “They do that for however long they need to lengthen. They may need to lengthen for three or four or five centimeters — that would be 30, 40 or 50 days.”

For very young patients, like those who are 5 or 6, whose bones are too small to accomodate a magnetic rod used for internal fixation, or what’s also called a magnetic intramedullary nail, external fixation is still the treatment of choice, Lalonde says. But he notes technology is advancing with smaller nails for pint-sized patients.

For kids and adults who go through it, limb lengthening surgery and follow-up is no minor undertaking. “The risks of limb lengthening are many. You’re taking an arm or a leg and you’re stretching it out, and so you’re stretching not only the bone, but you’re stretching nerves, skin, muscle,” Herzenberg says. “It doesn’t matter if you use an external device or an internal device, they can all cause muscle contractures, joint contractures, where you lose motion or ability to move your ankle or your knee, for example. They can all cause nerve stretch injuries, where the nerves don’t tolerate being stretched.” Usually this doesn’t happen, he adds, “because we go slowly and the nerves adapt. But there are some cases where it’s not tolerated.”

What’s more, experts say, it’s critical patients do physical therapy as instructed. “The physical therapy is an extremely important part of this, because we cut the bone, and you can lengthen the bone as much as you want — at least theoretically — but the muscles are not cut. The muscles have to stretch to adapt,” Herzenberg says. If a patient doesn’t do physical therapy as recommended, the muscles may not adapt. “So you’ve got a long leg, but short muscles, and then your joints don’t work so well,” he says.

[See: 5 Physical Therapy Procedures You Should Question.]

Brayton, who had a PRECICE rod put into his left femur last year by Herzenberg, says he followed physical therapy recommendations to a T — doing regular, intensive exercises and stretching for several months. He had the rod removed in June. “The challenging part was the physical therapy and the stretching and the lengthening and just getting the muscle back,” he says. But he says that now he has a permanent solution to his limb length discrepancy, and the problems it precipitated: “I’ve had zero pain,” he says. “I’ve had no hip pain, I’ve had no back pain.”

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What to Do When One Leg Is Shorter Than the Other originally appeared on usnews.com